U.S. patent application number 11/755378 was filed with the patent office on 2007-12-06 for methods of accelerating muscle growth, decreasing fat deposits and improving feed efficiency in livestock animals.
This patent application is currently assigned to BRIDGE PHARMA, INC.. Invention is credited to A.K. Gunnar Aberg.
Application Number | 20070282010 11/755378 |
Document ID | / |
Family ID | 38791087 |
Filed Date | 2007-12-06 |
United States Patent
Application |
20070282010 |
Kind Code |
A1 |
Aberg; A.K. Gunnar |
December 6, 2007 |
Methods of Accelerating Muscle Growth, Decreasing Fat Deposits and
Improving Feed Efficiency in Livestock Animals
Abstract
A method of promoting or improving the feed efficiency and the
muscle to fat ratio in animals by administering to the animals a
therapeutically effective amount of a pure or substantially pure
RR-isomer of ractopamine is disclosed. Also disclosed are animal
feed preparations and compositions and pharmaceutical preparations
capable of increasing lean meat deposition in an animal or
decreasing body fat, or promoting or improving the growth of an
animal or improving the feed efficiency of an animal. Feed
preparation, compositions and pharmaceutical preparations including
therapeutically effective amounts of a pure or substantially pure
RR-isomer of ractopamine are disclosed
Inventors: |
Aberg; A.K. Gunnar;
(Sarasota, FL) |
Correspondence
Address: |
VIKSNINS HARRIS & PADYS PLLP
P.O. BOX 111098
ST. PAUL
MN
55111-1098
US
|
Assignee: |
BRIDGE PHARMA, INC.
Sarasota
FL
|
Family ID: |
38791087 |
Appl. No.: |
11/755378 |
Filed: |
May 30, 2007 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60809205 |
May 30, 2006 |
|
|
|
60923506 |
Apr 13, 2007 |
|
|
|
Current U.S.
Class: |
514/651 |
Current CPC
Class: |
A61P 37/04 20180101;
A61K 31/7048 20130101; A61K 31/138 20130101; A61P 31/04 20180101;
A61P 21/00 20180101; A61K 31/137 20130101; A61P 3/00 20180101 |
Class at
Publication: |
514/651 |
International
Class: |
A61K 31/138 20060101
A61K031/138 |
Claims
1. A method of promoting muscle growth, decreasing fat deposits or
improving feed efficiency of animals, which comprises administering
to said animal an effective amount of the pure or substantially
pure RR-enantiomer of ractopamine or a pharmaceutically acceptable
salt, solvate or polymorph thereof.
2. A method of promoting muscle growth, decreasing fat deposits or
improving feed efficiency of animals, which comprises administering
to said animal an effective amount of the pure or substantially
pure RR-enantiomer of ractopamine or a pharmaceutically acceptable
salt, solvate or polymorph thereof, while minimizing or eliminating
the side effects residing in the corresponding racemic mixture of
RR--, RS--, SR-- and SS-isomers.
3. The method of claim 1, wherein said RR-isomer of ractopamine or
a pharmaceutically acceptable salt thereof is administered to said
animals as a feed or feed additive, containing the pure or
substantially pure RR-enantiomer of ractopamine or a
pharmaceutically acceptable salt, solvate or polymorph thereof in
concentrations from 1 ppm to 500 ppm.
4. The method of claim 1, wherein said RR-isomer of ractopamine or
a pharmaceutically acceptable salt thereof is administered to said
animals in the form of drinking water, containing the pure or
substantially pure RR-enantiomer of ractopamine or a
pharmaceutically acceptable salt, solvate or polymorph thereof in a
concentration from 1 ppm to 500 ppm.
5. The method of claim 1, wherein said RR-isomer of ractopamine is
administered for promoting muscle growth of livestock animals,
birds and farmed fish.
6. The method of claim 1, wherein said RR-isomer of ractopamine is
administered for decreasing body fat of livestock animals, birds
and farmed fish.
7. The method of claim 1, wherein said RR-isomer of ractopamine is
administered to livestock animals, birds and farmed fish for
improving feed efficiency.
8. The method of claim 2, wherein said side effect is stress with
concomitant aggression.
9. The method of claim 2, wherein said side effect is stress with
concomitant decrease in meat quality.
10. The method of claim 2, wherein said side effect is stress with
concomitant increase in mortality.
11. The method of claim 1, wherein said animals are ruminants.
12. The method of claim 1, wherein said animals are swine.
13. The method of claim 1, wherein said animals are horses.
14. The method of claim 1, wherein said animals are chicken or
turkeys.
15. The method of claim 1, wherein optically pure RR-ractopamine
contains 98 per cent by weight or more of RR-ractopamine and 2 per
cent or less by weight of the sum of RS--, SR-- and
SS-ractopamine.
16. The method of claim 1, wherein substantially pure
RR-ractopamine contains 80 per cent by weight or more of
RR-ractopamine and 20 percent or less by weight of the sum of RS,
SR and SS-ractopamine.
17. The method of claim 1, wherein pure or substantially pure
RR-enantiomer of ractopamine or a pharmaceutically acceptable salt,
solvate or polymorph thereof is administered in combination with an
effective amount of at least one antibacterial compound.
18. A feedstuff composition for animals, comprising the admixture
with protein-containing feed materials of the pure or substantially
pure RR-isomer of ractopamine, a pharmaceutically acceptable salt,
solvate or polymorph thereof.
19. The composition of claim 18 wherein said feedstuff also
contains an effective amount of at least one antibacterial
compound.
20. The composition of claim 19, wherein said antibacterial
compound is a beta-glucan.
21. A composition containing pure or substantially pure
RR-enantiomer of ractopamine or a pharmaceutically acceptable salt,
solvate or polymorph thereof, and at least one antibacterial
compound.
Description
RELATED APPLICATIONS
[0001] This patent document claims the benefit of priority of U.S.
application Ser. No. 60/809,205, filed May 30, 2006 and of U.S.
application Ser. No. 60/923,506, filed Apr. 13, 2007, which
applications are herein incorporated by reference.
FIELD OF THE INVENTION
[0002] The invention relates to methods of increasing the
muscle/fat ratio in an animal, promoting or improving the growth of
an animal and/or improving the feed efficiency of animals by
administering therapeutically active isomers of ractopamine or a
derivative thereof to the animals in a quantity which is effective
for this purpose. The invention further relates to compositions for
use in the methods and to animal feed additives, which comprise one
or more therapeutically active isomers of ractopamine as the active
substance. The present invention refers to the use of certain
adrenergic drugs in animals that have now surprisingly been found
not to induce stress or the aggravation of stress in said
animals.
BACKGROUND OF THE INVENTION
[0003] Adrenergic beta-agonistic drugs characteristically contain
as part of their structure an ethanolamine or 2-amino-ethanol
moiety. Since the chemical structures of these drugs usually
comprise at least one asymmetric carbon atom, these drugs commonly
exist in optically active isomeric form, with the chiral carbon
atom having (R) or (S) configuration. When there is a single
asymmetric carbon atom present, the beta-receptor agonists exist as
individual (R) or (S) enantiomers or in racemic (RS) form, i.e. as
a 50:50 mixture of (R) and (S) enantiomers.
[0004] Compounds with two chiral centers have four isomers: the
RR--, SS--, RS--, and SR-isomers. Such compounds (e.g. formoterol,
ractopamine) may exist in a number of forms i.e. in the pure RR or
SS or RS or SR isomeric forms, or as mixtures, hereinafter called
"enantiomeric pairs" of either RR/SS or RS/SR. The compound
ractopamine can also exist as racemic mixtures of all four isomers
(RR+SS+RS+SR) or in the form of racemic mixtures of the
enantiomeric pairs (RR/SS) or (RS/SR). The isomers (RR) and (SS)
are mirror images of each other and are therefore enantiomers,
which have the same chemical properties and melting points. (RS)
and (SR) is similarly an enantiomeric pair. The mirror images of
(RR) and (SS) are not, however, super imposable on (RS) and (SR).
This relationship is called diastereomerism, and (RR) is a
diastereomer to (RS).
[0005] Ractopamine has the molecular formula
C.sub.18H.sub.23NO.sub.3 and racemic ractopamine is typically
prepared as a hydrochloride salt. Chemically, ractopamine is
differs from dobutamine in the location of only one hydroxyl group,
but ractopamine is not a catecholamine and is therefore not
instantaneously metabolised by catechol-O-methyl transferase.
Ractopamine HCl
(4-hydroxy-a-[[[3-(4-hydroxyphenyl)-1-methylpropyl]amino]methyl]benzeneme-
thanol hydrochloride) has a molecular weight of 337.85 and a
molecular formula of C.sub.18H.sub.23NO.sub.3.HCl (CAS number:
90274-24-1). The racemate of ractopamine is a mixture of all four
isomers in approximately equal proportions.
##STR00001##
[0006] One form of ractopamine--the racemic mixture of all four
isomers (RR/SS/RS/SR) is commercially available under the trade
names PAYLEAN.RTM., Elanco and OPTAFLEX.RTM., Elanco and both are
used as growth promotants for livestock. The RR-isomer of
ractopamine is called Butopamine Hydrochloride, USAN and has
extensively been tested as a cardiac stimulator for humans by Leier
et al., which publications are hereby included by reference in
their entirety (Thompson, M J; Huss, P; Unverferth, M D; Fasola A;
Leier, C V: Hemodynamic effects of intravenous butopamine in
congestive heart failure. Clin Pharmacol Ther, 1980, 28: 324-334).
Butopamine was not further developed as human medication.
[0007] Although structurally identical, isomers can have different
effects in biological systems: one isomer may have specific
therapeutic activity while another isomer may have no therapeutic
activity or may have entirely different forms of biological
activity.
[0008] The pharmacological activity of beta-receptor agonists like
ractopamine is to activate adrenergic beta-receptors. Activation of
adrenergic beta-receptors leads to increased intracellular
concentration of cyclic adenosine monophosphate (cAMP), which
triggers various events in various cells and organs. Cellular
responses to beta-receptor activation include for example lipolytic
activity in adipose tissues, smooth muscle relaxant activity in the
bronchi and increased frequency of contractions in the heart
(Goodman-Gilman, The Pharmacological Basis of Therapeutics 9.sup.th
Ed., 1996 McGraw-Hill ISBN0-07-026266-7.) Most adrenergic
beta-receptor agonists have affinity for two or three types of
adrenergic beta-receptors. Thus, both salbutamol and ractopamine
have affinity for adrenergic beta-1 and beta-2 receptors, but
negligible affinity for beta-3 receptors. There is no significant
effect of ractopamine on adrenergic alpha-receptors (Colbert W E,
Williams P D, Williams G D: Beta-adrenoceptor profile of
ractopamine HCl in isolated smooth muscle and cardiac muscle
tissues of rat and guinea pig, J Pharm Pharmacol 1991, 43:
844-847.) It may therefore be concluded that ractopamine does not
have direct effects on adrenergic alpha-receptors in the brain.
[0009] Of the four isomers of ractopamine, which are RR--, RS--,
SR-- and SS-ractopamine, it is known that RR-ractopamine is the
most potent, both when tested in vitro (Mills S E, Kissel J,
Bidwell C A, Smith D J, Stereoselectivity of porcine
.beta.-adrenergic receptors for ractopamine stereoisomers. J. Anim.
Sci. 2003, 81: 122-129) and in vivo (Ricke E A, Smith D J, Feil V
J, Larsen G L, Caton J S, Effects of ractopamine HCl stereoisomers
on growth, nitrogen retention and carcass composition in rats. J.
Anim, Sci. 1999, 77:701-707, which publications are hereby included
in their entirety by reference.) Thus, when tested for binding
affinity for porcine adrenergic .beta.-2 receptors, RR-ractopamine
was about 2.5 times as active as the racemic mixture of all four
isomers (Mills et al., 2003.)
[0010] Adrenergic beta-receptor agonist drugs have pharmacological
and toxicological side effects that range from minor importance to
major importance. Bronchial smooth muscle relaxation by adrenergic
beta-2 stimulation may be a side effect of minor importance for
livestock animals. However, racemic ractopamine has been found to
cause CNS-mediated stress in livestock animals (Marchant-Forde J.
N., et al., The effects of ractopamine on the behaviour and
physiology of finishing pig" J Anim Sci., 2003, 81: 416-422, which
publication is hereby included in its entirety by reference.) This
is a side effect of major importance, as racemic ractopamine is
increasing the stress levels in animals during handling and
transport and is causing increased mortality during transport.
Stress in livestock animals, particularly in swine, is believed to
induce the PSE syndrome in the animals (poor meat quality that is
pale, soft and exudative, becoming dry upon cooking).
[0011] Ractopamine, having preference for adrenergic (cardiac)
.beta..sub.1 receptors, may cause tachycardia in livestock animals
by direct stimulation of cardiac .beta..sub.1 receptors, while
R-salbutamol, having preference for adrenergic .beta..sub.2
receptors is not causing tachycardia in the livestock animals
(Marchant-Forde J. N., et al., 2003 and London C. J., et al. 2005.)
However, it is nevertheless not known, if the significant
tachycardia in livestock animals by ractopamine is caused by
CNS-mediated stress or by direct beta-receptor stimulation or both,
but tachycardia is an unwanted side-effect, which may lead to
cardiac tachyarrhythmias and increased lethality of livestock
animals by sudden cardiac death (cardiac ventricular
fibrillation.)
[0012] In many animals including livestock animals, birds and fish,
stress manifests itself--directly or indirectly--in a range of
forms extending from irritability to aggression. Stress may lead to
cardiovascular side effects ranging from slightly elevated heart
rate to serious tachycardia and cardiac arrhythmias, which in turn
can lead to sudden death. The prevalence of stress-induced
lethality varies among species; some having higher stress
responsiveness than others (Odeh F. M., Cadd G. G., Satterlee D. G.
Genetic characterization of stress responsiveness in Japanese
quail. Poult Sci., 2003, 82: 31-35, which publication is hereby
included in its entirety by reference.)
[0013] Stress in horses can be expressed in various ways, such as
for example nervousness, anxiety and tachycardia and can be caused
for example by heat, transportation and feed withdrawal. Stress in
horses can also be induced by drugs or aggravated by drugs, such as
for example adrenergic beta-receptor agonists that may be given to
the horses of various reasons, such as for example as
bronchodilators in heaves. CNS-mediated stress in horses may also
lead to increased susceptibility for various diseases, such as for
example allergic diseases or infectious diseases such as
opportunistic bacterial infections. The use of an adrenergic
beta-agonist that does not cause stress is particularly important
in animals that are already suffering from stress or have a
propensity for developing stress.
[0014] Stress in pigs is very common and some pigs have been shown
to carry a specific stress-gene. Pigs that are homozygous to this
gene are particularly stress-prone although heterozygous pigs are
also more stress-prone than pigs that do not at all carry or
express the stress-gene (Sterle J.: The Frequency of The Porcine
Stress Gene in Texas Show Pigs. http://animalscience.tamu.edu,
which publication is hereby included in its entirety by reference.)
CNS-mediated stress in pigs can be expressed in various ways, such
as for example aggression, tail-biting, and tachycardia and can be
caused for example by heat, transportation, stocking density, human
interventions, feed withdrawal, disease and aggression between
males. Stress in pigs can also be caused or aggravated by drugs,
such as for example racemic ractopamine (Marchant-Forde et al.
2003.) Porcine Stress Syndrome (PSS) is triggered when pigs are
subjected to stress associated with transportation, restraint,
fighting, mating, exercise or hot and humid weather. Pigs with PSS
become dyspneic, hyperthermic, cyanotic, develop muscle rigidity
and such animals often die. Some degree of stress can be observed
in most pigs and most pigs may therefore have propensity for
stress. The administration of certain drugs, such as racemic
ractopamine to pigs may induce or aggravate PSS in swine. In
addition to the well-known fact that stress induces increased
mortality in swine, it has been demonstrated that stress has a
negative effect on the quality of meat. Thus, the muscles from
stress-positive pigs often show the PSE syndrome (pale, soft and
exudative). This condition causes the carcasses to be classified as
being of unacceptable or inferior quality, since the meat from such
animals tend to become dry when cooked. (Stadler K: Porcine Stress
Syndrome and Its Effects on Maternal, Feedlot and Carcass
Quantitative and Qualitative Traits. The University of Tennessee,
Agricultural Extension Service, PB 1606, which publication is
hereby included in its entirety by reference.) The use of an
adrenergic beta-agonist that does not cause stress is particularly
important in animals that are already suffering from stress or have
a propensity for developing stress.
[0015] Stress in ruminants can be expressed in various ways and in
cattle ranging from anxiety to aggression or depression, increased
body temperature and increased heart rate, and can be caused by a
variety of factors, such as changes in environment, transportation,
human contact, aggressive herd behaviour and changes in the herd
social rankings, hunger, thirst, fatigue, injury or thermal
extremes (Boissy, A. & Bouissou, M-F: Assessment of individual
differences in behavioural reactions to heifers exposed to various
fear-eliciting situations. Applied Animal Behaviour Science, 1995,
46:17-31; and Grandin, T.: Behavioural agitation during handling of
cattle is persistent over time. Applied Animal Behaviour Science,
1993, 36:1-9, which publications are hereby included in their
entirety by reference). The propensity for stress in cattle seems
to affect most animals and the administration of drugs, such as
racemic ractopamine may induce or worsen CNS-mediated stress in
cattle and particularly in cattle that are predisposed for stress.
Stress in cattle is a serious condition and may lead to decreased
quality of the meat and increased lethality among the animals. The
use of an adrenergic beta-agonist that does not cause stress is
particularly important in animals that are already suffering from
stress or have a propensity for developing stress.
[0016] As other examples of ruminants, sheep also develop symptoms
of CNS-mediated stress due to the same or similar factors as
described above for other species and may include but are not
limited to changes in the environment, transportation, human
contact, aggressive herd behaviour, hunger, thirst, fatigue, injury
or thermal extremes. The symptoms of CNS-mediated (psychological)
stress are similar to those of other species and include anxiety,
aggression, increased body temperature or increased heart rate. The
consequences of stress are similar to those described above for
other species and include risk for decreased quality of meat and
sudden death of the animals. The administration of drugs, such as
racemic ractopamine may induce stress in sheep--particularly in
predisposed animals or increase the symptoms of stress in said
species. Stress in sheep can be a serious condition and may lead to
decreased quality of the meat and increased lethality among the
animals. The use of an adrenergic beta-agonist that does not cause
stress is particularly important in animals that are already
suffering from stress or have a propensity for developing
stress.
[0017] As still another example, birds such as chickens ducks,
geese, turkeys, ostriches, emus or quails may also develop
CNS-mediated stress by doses of racemic ractopamine, corresponding
to those necessary for obtaining increased muscle weight, decreased
fat deposits and improved feed efficiency. Particularly, chickens
in "grower houses" are suffering from stress or are predisposed to
stress because of the high stocking density (up to 20,000 birds in
a very confined space). Symptoms of stress in birds, such as for
example chickens, ducks, geese, turkeys, ostriches, emus and
quails, can be expressed in various ways, as for example, anxiety,
aggression, increased body temperature, tachycardia and lethality
and can be caused for example by heat, transportation, high
stocking density, sudden environmental factors, feed withdrawal,
injury or disease. The administration of the beta-receptor agonist
racemic ractopamine may induce or increase stress in birds.
CNS-mediated stress in birds--and particularly in chicken--may lead
to decreased quality of the meat and increased lethality among the
animals.
[0018] Stress may also manifest itself in farmed fish, such as for
example barramundi, carp, cod, perch, salmon, trout and tilapia.
Symptoms of stress and symptoms for predisposition (propensity) for
stress in farmed fish can be observed as increased activity as for
example during feeding frenzy and stress can lead to sudden death
of the fish. Stress in fish can be caused for example by extreme
temperatures, environmental factors, disease, parasites, handling
or transportation. The administration of exogenous beta-receptor
agonists may lead to stress in animals that are predisposed for
developing stress or may cause a worsening of the symptoms of
stress in fish, leading to decreased quality of the meat and
increased lethality among the animals. The use of an adrenergic
beta-agonist that does not cause stress is particularly important
in animals that are already suffering from stress or have a
propensity for developing stress.
[0019] Stress in animals can be monitored, judged and rated by
individuals who are skilled in the art of animal psychology. In
addition to monitoring and rating the behaviour of the animals,
objective parameters are being used, such as for example
determination of the concentration of circulating corticosteroid
levels and heterophil counts. (Post J, Rebel J M J, ter Huurne A A:
Physiological Effects of Elevated Plasma Corticosterone
Concentrations in Broiler Chicken; An Alternate Means by which to
Assess the Physiological Stress. Poultry Science, 2003, 82:
1313-1318, which publication is hereby included in its entirety by
reference.) Depending on the species, stress in animals in response
to exogenous adrenergic stimulation can also be monitored by
parameters such as body temperature, heart rate, spontaneous
motility, aggression, ease of handling and even weight loss
(Marchant-Forde J. N. et al, 2003.)
[0020] The use of an adrenergic beta-agonist that does not cause
stress is particularly important in animals that are already
suffering from stress or have a propensity for developing stress.
The use of an adrenergic beta-agonist that does not cause stress is
particularly important in animals that are already suffering from
stress or have a propensity for developing stress. As mentioned
above, predisposition of stress in livestock animals is common and
it will be advantageous to avoid the worsening of the stress in
these animals that is induced by racemic ractopamine.
SUMMARY OF THE INVENTION
[0021] It has now surprisingly been found that parameters, such as
for example the amount of adipose tissue ("fat") in an animal, the
amount of muscle tissue ("lean meat") in an animal, growth of an
animal, the feeding efficiency of an animal, and the muscle-to-fat
ratio of an animal can be greatly improved by administering pure or
substantially pure RR-isomer of ractopamine, a pharmaceutically
acceptable salt, solvate or polymorph thereof, while side effects
such as aggressiveness and other symptoms of stress that can be
observed in animals given a formulation containing racemic
ractopamine can be avoided or substantially avoided. Thus, the
applicant has found that by administering a therapeutically
effective amount of the pure or substantially pure RR-isomer of
ractopamine, a pharmaceutically acceptable salt, solvate or
polymorph thereof, the beneficial effects of racemic ractopamine as
a growth promoter for livestock are maintained or improved, while
side effects such as aggressiveness and other symptoms of stress
that can be observed in animals given a formulation containing
racemic ractopamine can be avoided or substantially avoided. The
term "substantially avoided" indicates the side effects are
minimized, when administering the pure or substantially pure
RR-isomer of ractopamine, a pharmaceutically acceptable salt,
solvate or polymorph thereof at dosage rates at which racemic
ractopamine is customarily administered. Of course, very high
doses--such as doses used during toxicology testing--may still
induce the side effect.
[0022] The pharmacological explanation(s) for this surprising
finding is/are unknown, but a major drawback with ractopamine
administration is the drug-induced stress with concomitant negative
effects on the quality of the meat as well as the increased
mortality among animals treated with racemic ractopamine, can now
be completely or substantially avoided.
[0023] Accordingly, the invention provides a method of promoting or
improving the growth of an animal by administering to the animal an
effective amount of pure or substantially pure RR isomer of
ractopamine.
[0024] In particular, the present invention provides a method of
promoting muscle growth, decreasing fat deposits or improving feed
efficiency of animals, which comprises administering to said animal
an effective amount of the pure or substantially pure RR-enantiomer
of ractopamine.
[0025] In one embodiment, the present invention provides a method
of promoting muscle growth of an animal by administering to the
animal an effective amount of the pure or substantially pure
RR-isomer of ractopamine.
[0026] In another embodiment, the present invention provides a
method of improving the feed efficiency of an animal by
administering to the animal an effective amount of thepure or
substantially pure RR-isomer of ractopamine.
[0027] In another embodiment the invention provides a method of
improving the muscle to fat ratio in an animal by administering to
the animal an effective amount of thepure or substantially pure
RR-isomer of ractopamine.
[0028] Furthermore, it has surprisingly been found that the tissue
residues of total ractopamine are lower when RR-ractopamine is
being used as a growth promoter for livestock than when a racemic
mixture of ractopamine is being used. Thus, in another embodiment
the invention provides a method for decreasing tissue residues of
ractopamine by administering to the animal a therapeutically
effective amount of a ractopamine formulation that contains a pure
or substantially pure RR-isomer of ractopamine. Thus humans eating
the meat from livestock animals treated with RR-ractopamine, rather
than racemic ractopamine, will be exposed to decreased amounts of
total ractopamine. The term "total ractopamine" as used herein
refers to the sum of all ractopamine isomers, enantiomeric pair,
and metabolites thereof. The scientific explanation for the low
tissue residues of total ractopamine in animals given
RR-ractopamine is not known, but it can be speculated that lower
doses and an accelerated metabolism of RR-ractopamine, which has
now surprisingly been found, may contribute to the favorably low
tissue residues after administration of RR-ractopamine to livestock
animals.
[0029] In another embodiment the invention provides a method of
treating horses suffering from heaves by administering to these
horses an effective amount of the pure or substantially pure
RR-isomer of ractopamine. Using RR-ractopamine for horses suffering
from heaves induces effective bronchorelaxation. The therapeutic
goals will be achieved without causing or worsening drug-induced
CNS-mediated stress in these animals that often are significantly
predisposed to stress because of their breathing difficulties.
[0030] In another embodiment the invention provides a
protein-containing feed formulation including the pure or
substantially pure RR-stereoisomer of ractopamine. The feed
formulation is capable of increasing lean meat deposition in an
animal and/or of improving the lean meat/fat ratio in an animal
and/or promoting or improving the growth of an animal or improving
the feed efficiency of an animal. The formulation contains a
sufficient amount of a protein-containing animal feed mixed with
the pure or substantially pure RR-stereoisomer of ractopamine to
provide from about 1 to 500 ppm of RR-ractopamine in the feed. The
concentration of crude protein and minerals in feed for various
livestock animal species are well known to those skilled in the art
and will meet or exceed the limits suggested by the National
Research Council (1990.)
[0031] In still another embodiment the invention provides
compositions and pharmaceutical formulations for use in the above
methods, which include a therapeutically effective amount of the
pure or substantially pure RR-stereoisomer of ractopamine.
[0032] The use of the present invention will also facilitate the
handling of animals, in particular livestock animals, birds, farmed
fish and farmed crustaceans, since animals treated with racemic
ractopamine are frequently demonstrating symptoms of stress and are
therefore more difficult to handle than animals treated with pure
or substantially pure RR-ractopamine (Marchant-Forde et al.
2003.)
[0033] According to the present invention there are also advantages
of administering to animals an enantiomeric mixture consisting of
approximately 50% RR-ractopamine and approximately 50%
SS-ractopamine, or a eutectic mixture since such RR/SS enantiomeric
mixtures have surprisingly been found to offer the same advantages
as racemic mixtures containing all four isomers of ractopamine, but
said mixtures of RR-- and SS-ractopamine are having a lesser
propensity for causing stress and stress-related side effects than
a racemic mixture containing all four isomers of ractopamine. The
risk for racemization of the RR-isomer is eliminated or
significantly decreased when a mixture containing RR+SS
enantiomers, rather than a single isomer, is used.
[0034] There are also advantages of administering to livestock
animals an enantiomeric mixture consisting of approximately 50%
RS-ractopamine and approximately 50% SR-ractopamine, or a eutectic
mixture since such RS/SR enantiomeric mixtures have now been found
to offer the same advantages as racemic (RR--, RS--, SR--, and SS)
ractopamine. These RS/SR enantiomeric pairs have now been found to
offer the same advantages as a racemic mixture containing all four
isomers of ractopamine, but said mixtures of RS-- and
SR-ractopamine have a lesser propensity for causing side effects
than a racemic mixture containing all four isomers of ractopamine.
The risk for racemization is significantly decreased when a mixture
containing RS+SR enantiomers, rather than a single isomer, is
used.
DISCLOSURE OF THE INVENTION
General
[0035] Those skilled in the art will appreciate that the invention
described herein is susceptible to variations and modifications
other than those specifically described. The invention includes all
such variation and modifications. The invention also includes all
of the steps, features, formulations and compounds referred to or
indicated in the specification, individually or collectively and
any and all combinations or any two or more of the steps or
features. Each document, reference, patent application or patent
cited in this text is expressly incorporated herein in its entirety
by reference, which means that it should be read and considered by
the reader as part of this text. That the document, reference,
patent application or patent cited in this text is not repeated in
this text is merely for reasons of conciseness.
[0036] Any manufacturer's instructions, descriptions, product
specifications, and product sheets for any products mentioned
herein or in any document incorporated by reference herein, are
hereby incorporated herein by reference, and may be employed in the
practice of the invention.
[0037] The present invention is not to be limited in scope by the
specific embodiments described herein, which are intended for the
purpose of exemplification only. Functionally equivalent products,
formulations and methods are clearly within the scope of the
invention as described herein.
[0038] The invention described herein may include one or more
ranges of values (e.g. dose, concentration, etc). A range of values
will be understood to include all values within the range,
including the values defining the range, and values adjacent to the
range, which lead to the same or substantially the same outcome as
the values immediately adjacent to that value which defines the
boundary to the range.
[0039] Throughout this specification, unless the context requires
otherwise, the word "comprise" or variations such as "comprises" or
"comprising", will be understood to imply the inclusion of a stated
integer or group of integers but not the exclusion of any other
integer or group of integers. It is also noted that in this
disclosure and particularly in the claims and/or paragraphs, terms
such as "comprises", "comprised", "comprising" and the like can
have the meaning attributed to it in U.S. patent law; e.g., they
can mean "includes", "included", "including", and the like; and
that terms such as "consisting essentially of" and "consists
essentially of" have the meaning ascribed to them in U.S. patent
law, e.g., they allow for elements not explicitly recited, but
exclude elements that are found in the prior art or that affect a
basic or novel characteristic of the invention.
[0040] The term "animal" includes any animals that are bred for
human food, in particular livestock, or farm animals such as,
ruminants (such as for example cattle and sheep), horses, swine,
and deer, birds (such as for example chickens, turkeys, ducks,
quails and geese), and farmed fish and farmed crustaceans.
[0041] The term "ractopamine" in this document refers to the free
amine or to a salt or solvates of ractopamine.
[0042] Terms like "pure RR-ractopamine", "pure RR-isomer of
ractopamine" and the like, refer to ractopamine having an optical
purity of RR-ractopamine that is 98% by weight or better, which
means the RR-isomer is present at a concentration of 98% by weight
or more, while the total concentration (i.e. the sum) of the
corresponding RS--, SR-- and SS-isomers is 2% by weight or less,
based on the total amount of ractopamine present.
[0043] The terms "substantially pure RR-ractopamine",
"substantially pure RR-isomer of ractopamine" and the like, refer
to an optical purity of RR-ractopamine that is 80% by weight or
better which means a concentration of 80% weight or more of
RR-ractopamine and 20% by weight or less of the sum of the
corresponding RS--, SR-- and SS-isomers, based on the total amount
of ractopamine present. In a more preferred embodiment, a
"substantially pure RR-ractopamine" contains 90% by weight or more
of RR-ractopamine and 10% or less of the sum of the RS and SR and
SS-isomers of ractopamine.
[0044] The terms "stress" and "CNS-mediated stress" are used as
synonyms herein and refer to CNS-mediated (psychological) stress
(as opposed to exercised-induced stress) with consequences leading
to the expression of psychological symptoms such as for example
aggressiveness, and/or other symptoms such as changes in body
temperature, changes in the concentrations of circulating
corticosteroids, increased heart rate, increased mortality and
decreased quality of meat products.
[0045] The term "growth promoter" as used herein, refers to a
chemical entity that upon administration to livestock animals will
have a favourable effect on feed efficiency and on the
muscle-to-fat ratio in the carcass of said livestock animals.
[0046] The term "feed efficiency" as used herein, refers to the
relationship between feed intake and weight gain in livestock
animals. Improved feed efficiency means that the ratio feed
intake/weight gain is decreased.
[0047] The term "muscle-to-fat ratio" as used herein, refers to the
total weight of body fat, divided with the total weight of muscle
(meat). The compounds of the present invention cause a decrease in
total body fat and an increase in muscle weight, as described in
more detail elsewhere in this document.
[0048] Other definitions for selected terms used herein will be
found within the description of the invention and apply throughout.
Unless otherwise defined, all other scientific and technical terms
used herein have the same meaning as commonly understood by
individuals who are skilled in the art to which the invention
belongs.
DETAILED DISCLOSURE OF THE INVENTION
[0049] In case certain salt-forms of pure or substantially pure
isomers of ractopamine have a propensity of racemization, other
salt forms or the free amine form of said compound may have a
significantly lower propensity for racemization or can be
considered as being optically stable.
[0050] The present invention relates to method of administering to
animals a therapeutically effective amount of the pure or
substantially pure RR-isomer of ractopamine rather than racemic
ractopamine, whereby a decrease in body fat deposits, increase in
muscle mass and improvement of feed efficiency are obtained, while
alleviating the concomitant liability of certain adverse side
effects associated with the administration of a ractopamine
racemate. In addition, a promotion or improvement of growth
(increased weight gain) is obtained in most species.
[0051] The present invention also relates to a method of decreasing
residues of ractopamine in the carcasses of animals. To this end,
it has now been found that by administering to animals a
therapeutically effective amount of pure or substantially pure
RR-stereoisomer of ractopamine or of a ractopamine formulation
containing the pure or substantially pure RR-stereoisomer of
ractopamine rather than racemic ractopamine, a decrease of residual
concentration of ractopamine in the carcass is obtained.
[0052] It is understood by those skilled in the art that increased
body weight occurs when the increase in muscle weight exceeds the
loss in weight caused by the loss of fat tissue.
[0053] The term "ractopamine" as used herein refers not only to the
free base, but also refers to acid addition salts or solvates
thereof. Acid addition salts include, for example addition salts of
ractopamine prepared with various acids, for example, hydrochloric
acid, hydrobromic acid, sulphuric acid, phosphoric acid, nitric
acid, or organic acids, such as citric acid, fumaric acid, tartaric
acid, acetic acid, maleic acid, benzoic acid, p-toluenesulphonic
acid, methanesulphonic acid, and the like. Hydrate forms and
polymorphs are also included in the present invention; particularly
forms that can be manufactured as dry powder or forms that are
water-soluble. Reference is made to Merck Index 11th edition (1989)
items 9089, 209, 3927, 4628, 8223, 5053, 5836, 8142, 2347, 7765,
1840, 9720, 7461, 1317,4159, and 963 and references cited therein
and, for Am. Rev. Resp. Dis. 1988, 137: (4; 2/2) 32, the
disclosures of which are herein incorporated in their entirety by
reference. Importantly, the free amine form of pure, or
substantially pure RR-ractopamine, has now been found to be
optically stable.
[0054] Like other adrenergic beta-receptor agonists (WO 2006/064283
A1), racemic forms of ractopamine, enantiomeric pairs of
ractopamine and single isomers of ractopamine, such as for example
RR-ractopamine, are expected to have various polymorphs that may
have favourable crystalline structure and/or favourable chiral
stability and/or favourable biological effects. All such polymorphs
are hereby encompassed in the present invention.
[0055] Long-term stability testing of RR-ractopamine has not been
concluded and it is possible that the free amine or some of the
salt form(s) may be more optically and/or chemically stable than
the hydrochloride salt. The free amine has the chemical name
RR-4-hydroxy-a-[[[3-(4-hydroxyphenyl)-1-methylpropyl]amino]methyl]benzene-
methanol. RR-ractopamine hydrochloride has the chemical name
RR-4-hydroxy-a-[[[3-(4-hydroxyphenyl)-1-methylpropyl]amino]methyl]benzene
methanol HCl; melting point 176-176.5.degree.; optical rotation
[alpha].sub.D-22.7.degree.; [alpha].sub.365-71.2.degree. (c=3.7
mg/ml in methanol) (Merck Index, 1996, 12: 1392-1393).
[0056] As used herein, the terms "therapeutically effective amount"
or "effective amount" or the like refer to an amount of compound,
such as for example an adrenergic receptor agonist or an
antibacterial compound that is sufficient to obtain a sufficient
beneficial effect. In the present context and with regard to
animals, a sufficient beneficial effect is considered to be
present, if one or more of the aforementioned effects are achieved.
In particular, a sufficient beneficial effect is considered to be
present, if the treatment offers a financial return of at least the
cost of the treatment, more preferably at least three times the
cost of the treatment. The financial returns of the treatment may
vary among animal species and will depend on factors like decreased
mortality, decreased morbidity, improved meat quality, cost of
treatment, improved lean/fat pricing bonus, etc. As will be
realized by those skilled in the art, the amount of RR-ractopamine
constituting such an amount of drug will depend on the animal
species, the duration of the treatment and numerous other
factors.
[0057] The administration of racemic ractopamine is known to induce
stress in animals and can also cause worsening of existing stress
in said animals. The methods of the present invention are
particularly useful for treating animals with a growth promoter, a
repartitioning agent, etc., if said animals already suffer from
stress that is induced by their environment or by other factors,
since drug-induced stress by adrenergic beta-receptor agonists,
such as racemic (RR/SS+RS/SR) ractopamine may significantly add to,
potentiate, or make worse stress in the animals.
[0058] RR-ractopamine is a growth promoter and a repartitioning
agent for use in livestock or other animals. Although,
RR-ractopamine is not likely to cure stress, treatment of animals
with the repartitioning agent RR-ractopamine has surprisingly been
found not to worsen existing stress or induce stress in animals and
particularly not in animals that are predisposed or prone to
stress.
[0059] Preferably the RR-isomer of ractopamine will be used in the
method of the invention, where said method is used to treat animals
that are prone to stress. The use of the pure or substantially pure
form of the single isomer RR-ractopamine will eliminate or
substantially reduce drug-induced toxic effects and drug-induced
pharmacological side effects that reside in the RS--, SR-- or
SS-isomers of ractopamine. The use of the pure single isomeric form
of RR-ractopamine will completely eliminate all drug-induced toxic
effects that exclusively reside in the RS--, SR or SS-isomer of
ractopamine.
[0060] The use of a single RR-isomer of ractopamine, rather than
the racemic form of ractopamine, as a growth promoter in livestock
animals will decrease the tissue drug residues of total ractopamine
in the edible parts of livestock animal bodies since RR-ractopamine
has now been found to be more potent as a beta-receptor agonist
than racemic forms enantiomeric pairs or any other single isomer of
ractopamine and can therefore be used in lower doses than any other
form of ractopamine. The use of the RR-isomer by itself will
eliminate drug residues of the other isomers. The use of the single
RR-isomer rather than a racemic mixture may also have advantages at
the sites of metabolism and at the receptor sites, since drug
interactions and receptor down-regulation by the other isomers can
be avoided when a single isomer is used. The reason for the very
potent lipolytic activity of the RR-isomer of ractopamine is not
known, but may be due to effects on various types of adrenergic
receptors.
[0061] It is well known by farmers who are using the commercially
available form of ractopamine for livestock animals that this form
of ractopamine is causing stress in livestock animals
(Marchant-Forde J. N., et. al. 2003). It has now been found that
RR-ractopamine does not cause this side effect when used in doses
that correspond to regular doses of racemic ractopamine in
livestock animals. Stress is a significant side effect of racemic
ractopamine and causes increased heart rate and increased mortality
in animals, particularly during handling and transport, as well as
induction of the PSE syndrome (poor meat quality that is pale, soft
and exudative) in swine. It is considered to be a major improvement
of growth promoter therapy that the use of RR-ractopamine, rather
than racemic ractopamine will avoid the induction of stress or the
worsening of stress when used in doses suitable for growth
promotion in livestock animals.
[0062] Preferential selection of the RR isomer also offers
beneficial advantages since pro-inflammatory effects of the
distomers, i.e. SS--, SR-- and RS-isomer, and smooth muscle
hyperreactivity by distomeric molecules will be avoided. Such side
effects by the distomers may be exacerbated due to the
pharmacokinetic properties (slow metabolism) of said distomeric
forms of ractopamine. The avoidance of these side effects is of
particular importance when RR-ractopamine is used as medication for
horses, suffering from heaves.
[0063] Preferential selection of the RR isomer also offers
beneficial cardiac effects as this form of ractopamine has not
revealed detrimental effects on cardiovascular parameters in
animals at concentrations that correspond to the doses, which are
suitable for growth promotion, which means doses of RR-ractopamine
that decrease body fat, increase muscle mass, improve feed
efficiency or increase body weight of animals. Thus, RR-ractopamine
may be used while avoiding the induction or worsening of stress in
livestock animals, for improving the quality of the carcass and the
feed efficiency. The term "improving the quality of the carcass" as
used in this document implies an increase in lean muscle weight,
decrease in fat content, increase of the lean/fat ratio and
avoidance of impaired meat quality, such as for example dry meat,
discolored meat and PSE syndrome meat.
[0064] The methods of the present invention have advantages also
for the companion animal owner or the veterinarian who wishes to
increase leanness and trim unwanted fat from obese companion
animals, since the present invention provides the means by which
this can be accomplished.
[0065] For the farmers, the method of the present invention yields
leaner animals, which command higher prices from the meat industry.
It was also noted that feed efficiency and/or animal growth rate
are significantly enhanced when the methods of the present
invention are followed.
[0066] In one embodiment, the invention offers a method of
improving or promoting the growth of an animal by administering to
the animal a therapeutically effective amount of the single RR
ractopamine isomer. More particularly, the ractopamine used in this
form of the invention is the pure or substantially pure form of the
RR-isomer of ractopamine. When pure or substantially pure
RR-ractopamine is used as a growth promoter for livestock, it is
possible to reduce the dose from the doses used for racemic
ractopamine, thereby lowering costs handling and transports of the
less bulky material. Lowering the dose will have the added
advantage of lowering the tissue residues of the drug in the
carcasses of the livestock animals. When using ractopamine in
animals, the environmental impact will be reduced by using the pure
or substantially pure RR-isomer rather than any of the enantiomeric
pairs or any of the racemic mixtures of ractopamine, since neither
of the RS--, SR-- or SS-isomers or the metabolites thereof will
pollute the environment.
[0067] It may be particularly beneficial to eliminate or reduce the
administration of the distomeric RS--, SR-- and SS-isomers of
ractopamine to animals since the distomeric isomers may cause
side-effects both in the animals and in humans eating such animals
particularly since at least the SS-isomers is completely devoid of
adrenergic beta-receptor stimulating activity and the RS-- and
SR-enantiomers have reduced beta-receptor activity when compared
with RR-ractopamine as described in this document and in Shappell
et al, 2000 (Shappell, N. W., Feil V. J., Smith D. J., Larsen G.
L., McFarland D. C.: Response of C2C12 mouse and turkey skeletal
muscle cells to the beta-adrenergic agonist ractopamine. J. Anim.
Sci. 2000, 78: 699-708, which publication is hereby included in its
entirety by reference.)
[0068] Furthermore, although there usually is some variability from
one animal to another and from one species to another, by
administering an effective amount of only the RR-isomer of
ractopamine or at least substantially pure RR-isomer, it is
possible to accomplish a more targeted treatment of the animals. In
particular, this is important since it is not desirable to
administer to animals, and particularly not to livestock animals, a
compound with a multifaceted spectrum of pharmacological
activities, pharmacological side effects and toxic effects. The
term "a more targeted treatment" in this context means that by
using the pure or substantially pure RR-isomer, the therapeutic
activity of the RR-isomer can be taken advantage of without also
having unwanted consequences of the RS--, SR-- or SS-isomers.
[0069] In another embodiment, the present invention provides a
method of improving the feed efficiency of an animal by
administering to the animal a therapeutically effective amount of a
pure or substantially pure RR-ractopamine preparation devoid or
substantially devoid of the RS--, SR-- and SS-isomers of
ractopamine. More particularly, the ractopamine preparation used in
this form of the invention is a pure or substantially pure form of
the RR-isomer of ractopamine.
[0070] In still another embodiment, the invention provides a method
of increasing the muscle to fat ratio in an animal by administering
to the animal a therapeutically effective amount of a ractopamine
preparation devoid or substantially devoid of at least the SS
isomer of ractopamine. More particularly, the ractopamine
preparation used in this form of the invention is a pure or
substantially pure form of the RR-isomer of ractopamine, such forms
being the free amine form or salt form or a solvate form of said
RR-isomer.
[0071] In another embodiment, the present invention also provides a
method to improve the financial returns for livestock producers,
since low-fat carcasses can attract a premium price of more than 30
percent (International Egg and Poultry Revue, USDA, Aug. 2, 2005.
www.ams.usda.gov/poultry/mncs/International
PoutlryandEgg/2005Reports/x080205.pdf, which publication is hereby
included in its entirety by reference.)
[0072] In a further embodiment, the present invention provides
methods for prophylactic treatment of mammals with hereditary or
environmental risks for the development of obesity with
ractopamine. According to this embodiment, the present invention
provides a method for reducing excessive fat in animals and humans
in need thereof and in particular in obese companion animals and
obese humans by administering to the subject in need thereof, an
effective amount of a ractopamine preparation. More particularly, a
ractopamine preparation used in this form of the invention may
preferentially contain the pure or substantially pure RR-isomer of
ractopamine. However racemic ractopamine will also cause weight
loss in obese animals and will also have therapeutic value in the
treatment of obesity in animals and in humans. The invention also
relates to a method of treating obesity in animal, said method
comprises administering an adrenergic beta-receptor agonist, such
as ractopamine, in particular RR-ractopamine or the essentially
pure RR-ractopamine combination with at least one additional
compound of therapeutic value, in particular and anti-obesity drug,
such as for example a cannabinoid-1 receptor antagonist, such as
for example rimonabant, or a microsomal triglyceride transfer
protein inhibitor, such as for example mitratapide or dirlotapide.
Dirlotapide is presently marketed in the US as single-drug therapy
for the treatment of obesity in companion animals under the name
SLENTROL.RTM., Pfizer. As an alternative to simultaneous
co-administration of ractopamine+another active anti-obesity drug,
the treatment of obese animals may alternate between
therapeutically effective doses of for example ractopamine or an
isomer thereof and dirlotapide, which will have the added advantage
of improved therapy by avoiding or decreasing adrenergic receptor
down-regulation. Obesity in companion animals is usually defined as
such animals being 10% or more in overweight. The doses of the
therapeutic compounds depend on the size and the species of the
animals and the results sought and the efficacy of the compounds.
Thus, oral doses of 0.1 to 100 mg of RR-ractopamine, one to four
times daily may be an adequate dose-range for the treatment of most
companion animals and oral doses of a cannabinoid-1 receptor
antagonist may range from 1 mg to 100 mg, one to four times daily.
The therapeutic dose of a cannabinoid-1 receptor antagonist, such
as for example rimonabant, may range from 0.05 mg to 50 mg one to
four times daily and the daily dose of a microsomal triglyceride
transfer protein inhibitor, such as for example mitratapide may
range from 0.05 mg to 50 mg. The recommended dose of the microsomal
triglyceride transfer protein dirlotapide (Slentrol.RTM., Pfizer)
is up to 1 mg/kg body weight, twice daily and has to be adjusted
after about 2 months when used as single-drug therapy in obese dogs
(www.pfizerah.com/slentrol; which document is hereby incorporated
in its entirety by reference). Reduction of obesity is known to
improve health in all mammals and the therapy suggested here would
be useful also in humans. The invention may also provide
prophylactic treatment to mammals with hereditary or environmental
risks for the development of obesity. Thus the present invention
provides both symptomatic and prophylactic treatment for animals
and humans suffering from obesity or at risk for developing
obesity. Use of a single isomer of an adrenergic beta-receptor
agonist, such as for example RR-ractopamine, has the added
advantage over the corresponding racemate that drug residues and
drug exposure is decreased, since obese mammals administered a pure
and single eutomeric isomer are administered less drug than if they
are given the corresponding racemic mixture. It should be kept in
mind that distomeric isomers have pharmacological effects,
pharmacological side effects and toxic effects, such as for example
pro-inflammatory effects. There are also additional pharmacokinetic
advantages by using the pure or substantially pure RR-isomer of
ractopamine, relating to the activities at various adrenergic
receptor sites, as well as sites for the intestinal absorption and
the metabolism in the liver and elsewhere.
[0073] It is of particular importance to reduce or eliminate the
use of the RS--, SR and SS-isomers of ractopamine since in the
doses used in animals, these isomers are believed by the inventor
not to carry any (SS and SR) or only limited (RS) growth promotant
activity, but carry unwanted activities, such as for example risk
for stress with concomitant decrease in meat quality and
concomitant risk for lethality. There is a risk that
pharmacological side effects and toxic effects of the RS--, SR--
and SS-isomers of racemic ractopamine can be expressed in humans
who have been eating meat from animals that have been administered
racemic ractopamine, particularly if the racemic form of
ractopamine is given in high doses to livestock animals. There may
also be risks for unborn children and lactating infants when the
mother eats meat treated with a mixture of ractopamine isomers,
such risk being reduced or eliminated if the livestock animals are
treated with the single RR-isomer of ractopamine rather than a
racemic mixture of ractopamine or an enantiomeric pair of
ractopamine. Thus, the present invention is reducing the risk for
pharmacological side effects and toxic effects in humans, such side
effects being hereinbefore described and originating from drug
residues in animals, having been treated with a racemic mixture of
ractopamine or an enantiomeric pair of ractopamine.
[0074] The use of the single RR-isomer of ractopamine or
essentially pure RR-isomer in animal species, such as livestock
species, and in humans, minimizes or eliminates any side effect
that is the result of interaction by the SS--, RS-- or SR-isomers
of ractopamine with the efficacy, absorption, distribution,
metabolism and excretion of RR-ractopamine.
[0075] Use of the methods of the present invention provides a means
for improving the quality of meat from livestock animals by
reducing stress and factors leading to stress, said stress being
known to decrease the quality of meat (Sterle J.: The Frequency of
the Porcine Stress Gene in Texas Show Pigs.
http://animalscience.tamu.edu.; Chatillon G. (1994): "Transport
mortality has its origin in stress: how to get pigs to their
destination in good condition. Porc. Magazine 265: 37-41; Warris P.
D.; Brown S. N. and Adams S. J. M. 1994: "Relationship between
subjective and objective assessment of stress a slaughter and meat
quality in pigs. Meat Science 38: 329-340, which publications are
hereby included in their entirety by reference).
[0076] Use of the methods of the present invention also provides a
means of preventing or reducing morbidity, particularly
attributable to stress, stress during transportation, aggressive
interactions between animals and cardiovascular or respiratory
events caused directly or indirectly as a consequence of the
administration of the SS--, RS-- or SR-isomers of ractopamine to
the animals.
[0077] Use of the methods of the present invention also provides a
means of preventing or reducing smooth muscle hyperactivity or
hyperreactivity, as well as pro-inflammatory effects in mammals,
caused directly or indirectly as a consequence of the
administration of the SS--, RS-- or SR-isomers of ractopamine to
the mammal.
[0078] The environmental impact of dosing livestock animals with
RR-ractopamine rather than racemic ractopamine will be significant
since neither the RS--, SR and SS-isomers of ractopamine nor the
metabolites thereof will pollute the environment. Additionally, a
favourable environmental impact will come from the fact that the
doses of RR-ractopamine by weight will usually be lower than the
corresponding doses of racemic ractopamine.
[0079] The present invention also relates to food compositions
including an admixture of food materials containing the pure or
substantially RR-isomer of ractopamine. RR-ractopamine is
preferentially administered to animals that are being given a diet,
consisting of protein-containing food materials in order to build
muscle mass in said animals. Accordingly, in another embodiment,
the invention provides a protein-containing animal feed
preparation, to which has been added pure or substantially pure
RR-ractopamine. The amount of pure or substantially pure
RR-ractopamine will be generally chosen to provide from about 1 to
500 ppm of the pure or substantially pure RR-isomer of ractopamine
in said food material. The term "ppm" refers to "gram per ton" and
10 ppm equals 10 gram per metric ton.
[0080] The daily dose of RR-ractopamine to animals varies widely
and depends on the animal species, the routes of administration and
the effect sought. In general, the daily doses of RR-ractopamine to
animals varies between 0.01 mg to 500 mg per day, of which the
lowest doses are intended for small animals and the highest doses
are intended for large mammals.
[0081] When the purpose is to supplement animal feed with a
RR-ractopamine preparation (i.e. pure or substantially pure
RR-ractopamine) as herein described, said animal feed supplement
usually contains pure or substantially pure RR-ractopamine and a
suitable carrier or diluent. Such feed can be prepared by initially
admixing the ractopamine preparation with a suitable carrier or
diluent. Carriers suitable for use to make up the feed supplement
compositions may include the following: alfalfa meal, soybean meal,
cottonseed oil meal, linseed oil meal, sodium chloride, cornmeal,
cane molasses, urea, bone meal, corncob meal, rice kernel and the
like. The carrier promotes a uniform distribution of the active
ingredients in the finished feed into which the carrier is blended.
It thus performs an important function by ensuring proper
distribution of the active ingredient throughout the feed.
[0082] Of importance is that the feed to the animal contain
proteins, the presence of which in feed is a well-known
prerequisite for muscle growth in all species. The dietary protein
requirements for various livestock species are well known for those
skilled in the art. As an example, a maize-soybean meal diet,
formulated to meet or exceed National Research Council (1990)
recommendations for major nutrients can be used for broiler
chicken, wherein the crude protein concentration should preferably
not be less than 17 to 18 percent by weight of the feed.
[0083] If the supplement is used as a top dressing for feed, the
carrier likewise helps to ensure uniformity of distribution of the
active material across the top of the dressed feed.
[0084] If the intention is to supply animals with drinking water
that is supplemented with a racemic or single-isomeric ractopamine
preparation, a carrier can be prepared, containing a fixed
concentration of ractopamine in a suitable volume of a fluid, such
as water, which, in turn, can be added to the drinking water of the
animals, by adding said carrier volume directly to the drinking
water of the animal or by adding said carrier to an automatic
drinking system for animals.
[0085] The preferred medicated swine feed generally contain from 1
to 200 grams of pure or substantially pure RR-ractopamine per
metric ton of feed, the optimum amount for these animals usually
being from 1 to 100 grams per ton of feed.
[0086] The preferred medicated drinking water for swine will
generally contain from 1 to 100 ppm by weight of
RR-ractopamine.
[0087] The preferred medicated feed for ruminants, such as for
example cattle and sheep, generally contains from 5 to 500 grams of
pure or substantially pure RR-ractopamine per ton of feed, the
optimum amount for these animals usually being about 10 to 200
grams per ton of feed.
[0088] The preferred medicated drinking water for ruminants, such
as for example cattle and sheep, generally contain 5 to 500 ppm by
weight of RR-ractopamine.
[0089] The preferred medicated feed for birds, such as for example
chicken and turkeys, generally contain from 1 to 100 grams of pure
or substantially pure RR-ractopamine per ton of feed, the optimum
amount for these animals usually being about 2 to 50 grams per ton
of feed.
[0090] The preferred medicated drinking water for birds, such as
for example chicken and turkeys, generally contain 1 to 50 ppm by
weight of RR-ractopamine.
[0091] The magnitude of a therapeutic dose of RR-ractopamine to
horses in the management of heaves will vary with the severity of
the disease to be treated, and other conditions, such as for
example the size of the animal. The dose of RR-ractopamine used to
treat horses with heaves will offer an amount sufficient to
alleviate bronchospasms but insufficient to cause adverse effects.
The dose needed to obtain an optimal therapeutic effect will vary
and will depend on the dose frequency and will also vary according
to the age, body weight, and response of the individual horse. In
general, the total daily dose ranges when administered by
inhalation, for the conditions described herein, is from about 0.2
microgram to about 200 micrograms per kilogram bodyweight two or
four times daily. Preferably, a daily oral dose range should be
between about 0.2 milligrams to 200 milligrams, two to four times
daily; all doses will have to be titrated according to the severity
of the symptoms as well known by the caring veterinary staff. A
controlled-release tablet may be more convenient than an
instant-release tablet and may contain at least twice the amount of
RR-ractopamine as an instant release tablet or for example between
4 and 400 mg RR-ractopamine. Part of the dose of RR-ractopamine in
a controlled-release tablet may be contained in the coating of the
tablet for immediate release and the remaining dose of
RR-ractopamine may be contained in the core of the tablet for
controlled release later. Controlled-release tablets may be given
to the horse once or twice daily, while instant-release tablets may
have to be given to the horse up to 4 times daily. In managing the
horse suffering from heaves or from another bronchial ailment that
includes bronchial smooth muscle constriction or hyperactivity, the
therapy should be initiated at a lower dose, perhaps about twice
daily dosing with 1 milligrams to about 12 milligrams and increased
up to about twice daily dosage of 10 milligrams or higher depending
on the horse's global response. It is further recommended that
older horses and horses with impaired renal, or hepatic function,
initially receive low doses, and that they be titrated based on
individual response(s) and blood level(s). It may be necessary to
use dosages outside these ranges as will be apparent to those
skilled in the art. Further, it is noted that the treating
veterinarian would know how and when to interrupt, adjust, or
terminate therapy in conjunction with the individual horse's
response. Analogous dosages and dosage forms apply to other animal
species that may be administered RR-ractopamine to induce relief
from bronchoconstriction.
[0092] In a particular embodiment of the methods of the invention,
pure or essentially pure RR-ractopamine is administered in
combination with at least one antibacterial agent. The term
"antibacterial agent(s)" or "antibacterial compound(s)" or the
like, as used herein, comprises various types of compounds and feed
additives, such as compounds having bactericidal effects or
bacteriostatic effects and compounds that in other ways protect
from infections, such as for example immunostimulating compounds.
Examples of immunostimulatory compounds are for example beta
glucans or lipopolysaccharide-containing root extracts from the
plant astragalus membranaceus. Other natural compounds, such as for
example oil of oregan or carvacrol and medications, such as for
example tilorone, which improve the immunological defence of the
animals against infections by organisms such as for example virus,
fungus, bacteria or parasites are also known and may be useful,
particularly if used together. The doses of beta glucans vary among
species and will also depend on the efficacy sought. The oral doses
of beta glucans to swine and chicken are generally from 0.2 mg/kg
bodyweight/day to 4 mg/kg bodyweight/day and are mixed into the
feed of the animals, preferably 0.2 to 1.0 mg/kg bodyweight/day of
beta glucans having a particle size of 1 micron or less.
Antibacterial compounds, such as for example tylosin, bacitracin
and lincomycin, can be used for the prevention of infections or for
controlling or reducing infections and/or for promoting health or
growth (growth promotion), and/or for decreasing mortality. As an
example, tylosin may be administered for example to swine for
control of proliferative enteropathies (ileitis) that is caused or
associated with Lawsonia intercellularis, for improved feed
efficiency and/or for improved lean/fat ratio (increased
leanness.)
[0093] It has now been established that solutions containing
water-soluble salt forms of racemic formulations of ractopamine in
the drinking water are suitable for administration to animals, e.g.
swine, cattle, sheep, horses, chicken, and turkeys. The
concentrations of a water-soluble salt form of racemic ractopamine
in the drinking water are within the limits stated above for
medicated drinking water containing pure or essentially pure
RR-ractopamine for swine, cattle, sheep, horses, chicken, and
turkeys.
[0094] It has also been found that certain water-soluble but
chirally stable salts of pure or essentially pure RR-ractopamine
are well suited for administration in drinking water. The
biologically active forms of ractopamine are also suitable for
administration in implanted reservoirs, as for example reservoirs
to be implanted into the rumen of cattle or sheep, as described in
for example U.S. Pat. Nos. 6,855,334 and 6,974,587, which patents
are hereby included in their entirety by reference.
[0095] Eutectic mixtures of the ractopamine isomers may have
physicochemical and/or pharmacological and/or other advantages,
such as for example manufacturing advantages or solubility
advantages over racemic mixtures. Formulations containing
biologically active eutectic mixtures of ractopamine isomers or
enantiomeric pairs of ractopamine are included in the present
invention.
[0096] It was surprisingly found that RR/SS ractopamine has
advantages over a racemic mixture containing all four enantiomers.
Thus, a racemic mixture of the RR-- and SS-enantiomers, which
contains approximately 50% of each of the enantiomers, is
chemically and chirally stable and has metabolic and
pharmacokinetic advantages, and the use of the RR/SS-ractopamine
racemate is also reducing or eliminating side effects that are
residing in the RS-- and the SR-enantiomers. The enantiomeric pair
RR/SS-ractopamine is more potent than a ractopamine racemate of all
four isomers and the enantiomeric pair RR/SS-ractopamine may
therefore be used in doses that are lower than a racemic mixture of
all four isomers. The environmental impact of the RR/SS-ractopamine
mixture is less than the impact of a racemate containing all four
isomers. The concentrations of RR/SS-ractopamine in the feed of
various animal species are within the frames for each species as
stated above for RR-ractopamine. Water-soluble salt form of racemic
RR/SS-ractopamine in the drinking water to livestock animals are
within the limits for RR-ractopamine, as stated above for medicated
drinking water for swine, cattle, sheep, horses, chicken, and
turkeys. Thus, the RR/SS-ractopamine racemic mixture is useful as a
growth promoter for livestock animals, for reducing fat deposits in
animals and for improve the feed efficiency and thereby the
economics of the animal livestock industry.
[0097] In another embodiment, the invention provides compositions
and pharmaceutical formulations for the use of the
RR/SS-ractopamine racemic mixture as a growth promoter for
livestock, which includes a therapeutically effective amount of the
pure or substantially pure racemic mixture RR/SS-ractopamine. The
RR-enantiomer is expressing all or most of the growth-promoting
activity of the enantiomeric pair RR/SS, while the presence of the
SS-enantiomer will prevent racemization. Thus, in cases where there
is risk for racemization of RR-ractopamine, RR/SS can be the
preferred compound. The formulations to be used for the RR/SS
racemic mixture are similar to the feed and drinking water
formulations for RR-ractopamine, described herein, wherein
RR/SS-ractopamine is used instead of RR-ractopamine.
RR/SS-ractopamine can be co-administered with other compounds as
described for RR-ractopamine above.
[0098] The terms "pure RR/SS-ractopamine", "pure RR/SS-racemate of
ractopamine" and the like as used herein, indicate a enantiomeric
purity of RR/SS-ractopamine that is 98%, or better, which means
that pure RR/SS-ractopamine contains 98% by weight or more of
RR/SS-ractopamine and 2% by weight or less of the sum of the RS--
and SR-enantiomers.
[0099] The terms "substantially pure RR/SS-ractopamine",
"substantially pure RR/SS-mixture of ractopamine" and the like as
used herein, refer to enantiomeric purity that is 80% or better,
which means that substantially pure RR/SS-ractopamine contains 80%
by weight or more of RR/SS-ractopamine and 20% or less of the sum
of the RS-- and SR-enantiomers. In a more preferred embodiment the
purity of substantially pure RR/SS-ractopamine is 90% by weight or
better, which means 90% by weight or more of RR/SS-ractopamine and
10% by weight or less of the sum of the RS and SR enantiomers of
ractopamine.
[0100] In still another embodiment the invention provides
compositions and pharmaceutical preparations for use in above
methods, which include a therapeutically effective amount of the
pure or substantially pure racemate RR/SS ractopamine.
[0101] Eutectic mixtures of the RR and SS-enantiomers may have
certain physicochemical, pharmacological and manufacturing
advantages over racemic mixtures. Formulations containing eutectic
mixtures of the RR-- and SS-enantiomers are included in the present
invention.
[0102] It was surprisingly found that mixtures of the two
enantiomers RS-ractopamine and SR-ractopamine have advantages over
a racemic mixture containing all four RR, RS, SR and SS isomers.
Thus, an enantiomeric pair of the RS-- and SR-enantiomers, which
contains approximately 50% of each of the two enantiomers, has
metabolic and pharmacokinetic advantages, and RS/SR-ractopamine is
also completely devoid of any side effects that are exclusively
residing in the RR-- and the SS-isomers. It has been suggested that
the SR-enantiomer contributes to the drug-induced increase more
than the RS-enantiomer, despite the fact that RS-ractopamine has
higher affinity for beta-receptors than the SR-enantiomer (Mills,
Kissel et al., 2003). It has not been shown if this actually is the
case in all species and in all types of tissues and the relative
importance of RS and SR is therefore not known. However, one of the
two enantiomers (RS or SR) is dominating (eutomeric) in various
tissues or organs (or species) after administration of the
enantiomeric pair RS/SR to animals and the main purpose for
including both enantiomers is be sure that functional adrenergic
beta-stimulation will occur and to prevent the racemization of the
eutomer. The enantiomeric pair RS/SR-ractopamine is expressing
stress in the animals to a lesser degree than the racemic mixture
containing all four isomers. The environmental impact of
RS/SR-ractopamine is significantly less than the impact of a
racemate containing all four isomers. The concentrations of
RS/SR-ractopamine in the feed of various animal species are within
the frames for each species as stated above for RR-ractopamine. The
concentration of a water-soluble salt form of RS/SR-ractopamine in
the drinking water is within the limits stated above for
RR-ractopamine in medicated drinking water for swine, cattle,
sheep, horses, chicken and turkeys. In another embodiment, the
invention provides compositions and pharmaceutical formulations for
the use of the RS/SR-ractopamine racemic mixture as a growth
promoter for livestock, which include a therapeutically effective
amount of the pure or substantially pure enantiomeric pair
RS/SR-ractopamine. The formulations to be used for
RS/SR-ractopamine mixture is similar to formulations of
RR-ractopamine in feed described herein, wherein RS/SR-ractopamine
is used instead of RR-ractopamine. A eutectic mixture of the RS and
SR-enantiomers has certain physicochemical, pharmacological and
manufacturing advantages over racemic mixtures.
[0103] The terms "pure RS/SR-ractopamine", "pure RS/SR enantiomeric
pair of ractopamine" and the like refer to an enantiomeric purity
of RS/SR-ractopamine that is 98%, or better, which means that pure
RS/SR-ractopamine contains 98% by weight or more of
RS/SR-ractopamine and 2% by weight or less of the sum of the RR--
and SS-enantiomers.
[0104] The terms "substantially pure RS/SR-ractopamine",
"substantially pure RS/SR enantiomeric pair of ractopamine" and the
like as used herein, refer to an optical purity of 80% or better,
which means that substantially pure RS/SR-ractopamine contains 80%
by weight or more of RS/SR-ractopamine and 20% by weight or less of
the sum of the RR-- and SS-isomers. In a more preferred embodiment
the optical purity of substantially pure RS/SR-ractopamine is 90%
by weight or better, which means 90% or more of RS/SR-ractopamine
and 10% or less of the sum of the RR-- and SS-isomers of
ractopamine.
[0105] In still another embodiment, the invention provides
compositions and pharmaceutical preparations for use in above
methods, which include a therapeutically effective amount of pure
or substantially pure RS/SR ractopamine as shown above for
RR-ractopamine.
[0106] A eutectic mixture of the RS and SR-enantiomers has certain
physicochemical, pharmacological and manufacturing advantages over
racemic mixtures. Formulations containing eutectic mixtures of the
RS-- and SR-enantiomers are included in the present invention.
[0107] In the present method, the various forms of
ractopamine--including RR-ractopamine and the enantiomeric pairs
described above--can be administered by any suitable means,
including parenterally, transdermally, subcutaneously,
intravenously, intramuscularly or orally, topically, nasally,
rectally, by inhalation or via implanted reservoirs or pellets
containing the drug. The preferred route of administration is the
oral route, with the drug mixed into the feed or the drinking water
of animals.
[0108] When administered in the feed or in the drinking water, the
active ingredient (for example RR-ractopamine) is prepared as a
powder or as a granulate, by methods known to those skilled in the
art. Powders may be sifted and/or milled as is also known to those
skilled in the art. The powder/granulate is mixed into a carrier as
previously described. The carrier or a carrier/feed mixture
material may be sold commercially for final mixing into the animal
feed by the end-user. Since RR-ractopamine has a short biological
half-life, no withdrawal period is needed and RR-ractopamine can be
fed to the livestock animals until the day of slaughter.
[0109] The form in which the drug will be administered (e.g.
injectables, inhalants, powders, granulates, tablets, capsules,
solutions, emulsions, subcutaneous pellets, transdermal patches,
suppositories, sprays, aerosols or reservoirs to be implanted into
the rumen of cattle or sheep, etc.) will depend on the route by
which it is administered. The drug, as for example RR-ractopamine,
may be administered orally in tablets, granulae, powder, capsules,
caplets, solutions, suspensions or similar forms. Formulations for
oral use may contain the active ingredient(s) in admixture with
non-toxic pharmaceutically acceptable excipients. These excipients
may be, for example, inert diluents, such as calcium carbonate,
sodium chloride, lactose, calcium phosphate or sodium phosphate;
granulating and disintegrating agents, for example, potato starch
or alginic acid; binding agents, for example, starch, gelatine or
acacia; and lubricating agents, for example, magnesium stearate,
stearic acid or talc. Other pharmaceutically acceptable excipients
can be colorants, flavouring agents, plasticizers, humectants etc.
Tablets may be uncoated or they may be coated by known techniques,
optionally to mask taste, delay disintegration and absorption in
the gastrointestinal tract and thereby provide a sustained action
over a longer period (i.e. controlled release). For example, a time
delay material such as glyceryl monostearate or glyceryl distearate
may be employed.
[0110] Formulations for oral use of RR-ractopamine or any of the
racemates described herein may also be presented as chewing
tablets, or as hard gelatin capsules wherein the active ingredient
is mixed with an inert solid diluent, for example, calcium
carbonate, calcium phosphate or kaolin, or as soft gelatin capsules
wherein the active ingredient is mixed with water or an oil medium,
for example, peanut oil, liquid paraffin, or olive oil.
[0111] Powders, dispersible powders or granules suitable for
preparation of an aqueous suspension by addition of water are also
convenient dosage forms of the present invention. Formulation as a
suspension provides the active ingredient in admixture with a
dispersing or wetting agent, suspending agent and one or more
preservatives. Suitable dispersing or wetting agents are, for
example, naturally-occurring phosphatides, as e.g. lecithin, or
condensation products of ethylene oxide with e.g. a fatty acid, a
long chain aliphatic alcohol or a partial ester derived from fatty
acids and a hexitol or a hexitol anhydrides, for example,
polyoxyethylene stearate, polyoxyethylene sorbitol monooleate,
polyoxyethylene sorbitan monooleate etc. Suitable suspending agents
are, for example, sodium carboxymethylcellulose, methylcellulose,
sodium alginate etc.
[0112] Additionally, other preferred forms of administration are by
inhalation or by transdermal delivery systems or subcutaneous
delivery systems, which will reduce or avoid gastrointestinal
metabolism and hepatic first-pass metabolism by metabolizing
enzymes; such delivery systems may be designed to prolong the
absorption or decrease the peak plasma drug concentration or to
increase the exposure of the animal to the drug (increased AUC,
meaning Area Under a Curve where plasma drug concentration has been
plotted over time).
[0113] Preparations of RR-ractopamine or any of the enantiomeric
pairs described herein may also be administered parenterally
(intravenous, intramuscular, subcutaneous or the like) in dosage
forms or formulations containing conventional, non-toxic
pharmaceutically acceptable carriers and adjuvants. The formulation
and preparation of such compositions is well known to those skilled
in the art of pharmaceutical formulations. Additional information
can be obtained in medical and pharmaceutical textbooks, such as
for example Goodman & Gilman: The Pharmacological Basis of
Therapeutics. Section 1. McGraw-Hill, Ed 9, ISBN 0-07-026266-7. For
parenteral use, the pharmaceutical compositions according to the
invention may comprise the preparation in the form of a sterile
injection. To prepare such a composition, the preparation is
dissolved or suspended in a parenterally acceptable liquid vehicle.
Among acceptable vehicles and solvents that may be employed are
water, water adjusted to a suitable pH by addition of an
appropriate amount of hydrochloric acid, sodium hydroxide or a
suitable buffer, 1,3-butanediol, Ringer's solution and isotonic
sodium chloride solution. The aqueous formulation may also contain
one or more preservatives, for example, methyl, ethyl or n-propyl
p-hydroxybenzoate.
[0114] For parenteral administration ractopamine preparations may
be prepared in the form of a paste or pellet and administered as an
implant, usually under the skin of the head or ear of the animal in
which increase in lean meat deposition and improvement in lean meat
to fat ratio is sought.
[0115] As an alternative to a paste, pellet or subcutaneous
implant, parenteral administration may involve injection of a
solution, containing sufficient amount of the pure or substantially
pure RR-ractopamine to provide the animal with 0.1 to 100 mg/day of
the active ingredient. Preferred parenteral dosages for swine,
cattle, and sheep are in the range of from 0.5 to 100 mg/day of
pure or substantially pure RR-ractopamine; whereas, the preferred
dose level of said parenteral ractopamine preparation for chicken
and turkeys are in the range of from 0.05 to 20 mg/day.
[0116] For the rectal application, suitable dosage forms for a
composition according to the present invention include
suppositories (emulsion or suspension type), and rectal gelatin
capsules (solutions or suspensions). In a typical suppository
formulation, the ractopamine preparation is combined with an
appropriate pharmaceutically acceptable suppository base such as
cocoa butter, esterified fatty acids, glycerinated gelatin, and
various water-soluble or dispersible bases like polyethylene
glycols and polyoxyethylene sorbitan fatty acid esters. Various
additives like e.g. enhancers or surfactants may be
incorporated.
[0117] For the nasal application, typical dosage forms for a
composition according to the present invention include nasal sprays
and aerosols. In a typical nasal formulation, the active
ingredients are dissolved or dispersed in a suitable vehicle. The
pharmaceutically acceptable vehicles and excipients and optionally
other pharmaceutically acceptable materials present in the
composition such as diluents, enhances, flavouring agents,
preservatives etc. are all selected in accordance with conventional
pharmaceutical practice in a manner understood by the persons
skilled in the art of formulating pharmaceuticals.
[0118] The ractopamine preparations according to the invention may
also be administered topically on the skin for percutaneous
absorption in dosage forms or formulations containing
conventionally non-toxic pharmaceutically acceptable carriers and
excipients that may include microspheres and liposomes. The
ractopamine preparations include creams, ointments, lotions,
liniments, gels, hydrogels, solutions, suspensions, pastes,
plasters and other kinds of transdermal drug delivery systems. The
ractopamine preparations may include emulsifying agents,
antioxidants, buffering agents, preservatives, humectants,
penetration enhancers, chelating agents, gelforming agents,
ointment bases, perfumes and skin protective agents.
[0119] The quantity of the drug to be administered to an animal
will have to be titrated for each species. In general, the doses of
the RR-ractopamine preparation to be used in swine may--as an
example--be about 2 to 10 ppm, e.g. about 5 ppm of RR-ractopamine
included in the feed for swine. With a total treatment period of 28
days and 20 to 100 mg/head/day, e.g. about 50 mg/head/day, this
corresponds to a total consumption of 0.56 to 2.8 grams, e.g. about
1.4 grams of RR-ractopamine for each swine. It is usually
calculated that finishing swine have a feed consumption of 3
kg/day. The doses of the RR-ractopamine preparation to be used in
cattle may--as an example--be about 20 ppm of RR-ractopamine in
feed for cattle and a treatment period of 28 days and 200
mg/head/day, this corresponds to a total consumption of 5.6 grams
of RR-ractopamine for each cow. It is usually calculated that
finishing cattle have a feed consumption of 10 kg/day. The total
consumption of RR-ractopamine will be decreased or increased with
changes in the feed inclusion of RR-ractopamine and with changes in
the duration of the treatment period. The daily dose of
RR-ractopamine to cattle may be as high as 500 mg/head/day. It is
common and it may be found advantageous to change the feed
inclusion of RR-ractopamine during the treatment period and all
changes in the doses administered to the animals will of course
influence the total consumption per animal of active
ingredient.
[0120] Since RR-ractopamine has a short biological half-life, no
withdrawal period is needed and RR-ractopamine can be fed to the
animals until the day of slaughter.
[0121] It may be advantageous to administer RR-ractopamine as an
implantable subcutaneous controlled-release pellet, designed to
deliver from 1 mg/day to 300 mg/day for the entire treatment
period, which may last up to six or eight weeks, whereupon the
animal may be slaughtered without any withholding period (drug-free
days before slaughter) or with a short withholding period of one to
three days. For all livestock species, the doses of RR-ractopamine
have to be carefully titrated and will depend on the
pharmacological efficacy of the drug in the selected species or
sub-species, the metabolic fate and rate of excretion of the drug
in various species, the route of administration, the size of the
animal and the results sought. In general, quantities of growth
promotant sufficient to decrease body fat, increase muscle mass,
and improve feed efficiency will be administered. The actual dosage
(quantity administered at a time) and the number of administrations
per day will depend on the pharmacokinetic property of the drug and
the metabolism of the drug in the body of the specific animal
species. For example about 10 to 3000 micrograms of the pure
RR-isomer of ractopamine may be given by various forms of
inhalation devices, such as metered dose inhalers and nebulizers,
0.01 to 500 milligrams may be given by the oral route (for example
as powders, granulates, tablets or liquids) one to four times per
day (or as ad lib daily doses to animals) and may be an adequate
dose in most livestock animals to produce the desired effect.
Suitable oral doses in humans include doses in the range of 0.05 mg
to 5 mg once daily or said doses given repeatedly up to six times
during the day. The actual and finally titrated drug doses may be
higher or lower and administration may take place more or less
frequently than indicated above, as determined by clinical studies
or by the caring individual, physician or veterinarian.
[0122] Sterile solutions for use in nebulizers are supplied in
unite-dose, low-density polyethylene (LDPE) vials as a clear,
colourless, sterile, preservative-free, aqueous solution containing
different doses of RR-ractopamine (0.63 mg, 1.25 mg, 5 mg, etc.).
The concentrations shown here are examples only. Other
concentrations may be manufactured for use by the caring veterinary
staff. Metered dose dispensers may contain the API (RR-ractopamine)
as a solution or as a micronized suspension.
TABLE-US-00001 Quantity Contained in Each Metered Dose Dispenser
Formula 7.5 ml (10.5 g) Canister RR-ractopamine (free amine) 1.8 mg
Trichloromonofluoromethane 5.16 g Dichlorodifluoromethane 5.16 g
Sorbitan trioleate 0.105 g
Each actuation delivers 90 mcg of RR-ractopamine. Multiple
actuations will be given to the horse for acute treatment of airway
obstruction. Alternatively, devices that deliver larger volumes of
RR-ractopamine can be used. Metered dose dispensers may also
dispense the API as a dry powder, as is well known to those skilled
in the art.
[0123] It is recognized that more than one pellet, tablet or dose
may be administered to an animal to achieve the desired dose level
which will provide the increase in lean meat production and
improvement in lean meat to fat ratio desired. Moreover, it has
been found that implants may also be made periodically during the
animal treatment period in order to maintain the proper drug level
in the animal's body.
[0124] The pharmacological side effects of RR-ractopamine in high
dose include tremor and tachycardia. These and other side effects
may be of short duration and may be associated with peak plasma
concentrations of the drug in connection with a drug overdose.
These side effects can be reduced or completely avoided by
admixture of the RR-ractopamine formulation into the feed or the
drinking water of livestock animals or by using drug delivery
systems that slowly release the drug of the present invention into
the systemic circulation. Such slow-release or controlled-release
delivery systems include granulae, tablets, capsules, subcutaneous
pellets or forms of reservoir depots with slow-release or
controlled-release properties that are designed to release the
active ingredient slowly or in a controlled manner.
[0125] In the method of the present invention, the RR-isomer of
ractopamine or either of the RR/SS or the RS/SR enantiomeric pairs
of ractopamine can be administered together with one or more other
active compound(s). Compounds that improve or prolong the
therapeutic effect of beta-agonists, e.g. compounds that delay or
inhibit the absorption or the metabolic degradation of the
compound, may also be co-administered with the adrenergic
beta-receptor agonist to further improve the therapeutic activity.
Other drugs such as for example other growth promoting agents and
antibacterial compounds may be combined with the selected drug of
the present invention to obtain improved health of the animal or
improved growth-promotant activity of the formulation.
[0126] Antibacterial agents may be used together with compounds of
the present invention in order to prevent or control infections by
bacteria, virus, fungus and/or parasites or to improve on possible
antibacterial effects of the compounds of the present invention.
Antibacterial compounds also have growth promoter activity by
unknown mechanisms of action. Thus antibacterial agents may
increase or promote or potentiate the effects of the compounds of
the present invention on fat reduction, muscle growth and/or feed
efficiency.
[0127] Eutectic mixtures containing RR-ractopamine and another
active component or other active components may be used and may
have certain biological advantages, such as for example leanliness
(muscle/fat), pharmacokinetic or metabolic advantages or may have
improved side effects or improved receptor activity as realized by
those skilled in the art of chiral drug pharmacology. Eutectic
mixtures of RR-ractopamine+SS-ractopamine or of
RS-ractopamine+SR-ractopamine can also be expected to have certain
advantages, such as for example improved receptor activation,
improved water solubility, improved chiral stability and/or
facilitated manufacturing.
[0128] RR-ractopamine can be used for weight loss therapy and will
cause loss of fat tissue in obese animals and humans. When used for
weight-loss purposes, the administration of RR-ractopamine should
preferably be combined with appropriate life-style modifications,
such as for example modified eating habits and increased exercise.
RR-ractopamine can also be combined with other anti-obesity drugs
having the same mechanisms of action as RR-ractopamine, or
different mechanisms of action.
Chemistry
[0129] Racemic ractopamine can be made by methods that are obvious
to those skilled in the art of chemistry. A synthetic method was
described by van Dijk J. and Moed H. D. in Recueil des Traveaux
Chimiques, 1973, Vol. 92: 1281-1297 and is hereby included in its
entirety by reference. A synthetic method for ractopamine was also
described by Anderson D. B. et al. (Eli Lilly): Growth Promotion.
U.S. Pat. No. 4,992,473, which is hereby included in its entirety
by reference.
[0130] Racemic ractopamine can also be isolated and purified from
conveniently available commercial sources. One kilogram of
commercially available Paylean.RTM. (Elanco) was stirred overnight
with 15 L of water. The mass was filtrated, and the filtrate (11.5
L) was evaporated under reduced pressure to a small volume (ca. 1-2
L). Aqueous potassium carbonate was added to raise pH to ca. 10,
and the solution was extracted twice with equal volumes of ethyl
acetate. The ethyl acetate extracts were combined, evaporated under
reduced pressure to ca. 0.5 L, and an equal volume of hexanes
added. After standing overnight, crystals of ractopamine free base
(6.83 g) were filtrated. This material was crystallized again from
ethyl acetate/hexanes to give pure ractopamine free base (6.01 g).
HPLC showed 98.5% purity. A sample of ractopamine free base (120
mg) was stirred with 10 ml of deionized water cooled in an
ice-water bath, and 2 M aqueous hydrochloric acid (2 ml) was added
slowly. After stirring to dissolve the material, the solution was
filtered and lyophilised to give ractopamine hydrochloride (125
mg). The mp was 128-135.degree. C., lit (Merck Index) mp
124-129.degree. C. .sup.1H NMR was consistent. HPLC showed 98.0%
chemical purity.
[0131] The RR-isomer of ractopamine can also be obtained by
stereoselective synthesis, using optically active starting
material(s) as know to those skilled in the art of synthetic
chemistry and as described by Van Dijk et al. (Van Dijk J. and Moed
H. D. in Recueil des Traveaux Chimiques, 1973, 92: 1281-1297),
which publication is hereby incorporated in its entirety by
reference.
[0132] The ractopamine isomers can be synthesized according to the
methodology of Ricke et al., 1999, which is hereby included by
reference in its entirety (Ricke E A, Smith D J, Feil V J, Larsen G
L, Caton J S: Effects of ractopamine HCl stereoisomers on growth,
nitrogen retention and carcass composition in rats. J. Anim,
Sci.1999. 77:701-707, which publication is hereby included in its
entirety by reference)
[0133] The stereoisomeric compound to be used may be separated from
the other stereoisomers by means of techniques known per se, for
example, selective crystallization of an addition salt with a
stereoisomer of an acid with a chiral center. However,
stereoselective synthesis, using a stereochemically pure starting
material or a stereochemically pure intermediate product can also
be used.
[0134] Methods for the preparation of RR-ractopamine have been
described by Mills J. et al. in Eur. Pat Appln 7,205 and by
Anderson D. B. et al. in U.S. Pat. No. 4,690,951, both of which are
hereby incorporated in their entirety by reference. Additional
information is available in chemical literature, such as for
example: Stereochemistry of Carbon Compounds, E. L. Eliel, McGraw
Hill 1962; "Tables of Resolving Agents," S. A. Wilen and
Lochmuller, L. H. et al., 1975, J. Chromatogr. 113(3): 283-302,
which publication is hereby included in its entirety by reference.
Additionally, a method for the preparation of RR-enantiomeric
phenethanolamines was described by Anderson D. B. et al. in Growth
Promotion, U.S. Pat. No. 5,643,967, which patent is hereby included
by reference in its entirety.
Biological Effects
[0135] Background.
[0136] The growth promotant activity of the adrenergic
beta-receptor agonist ractopamine has been demonstrated in various
livestock species. See for example: Watkins L. E.; Joens D. H.;
Mowrey D. H.; Anderson D. B. and Veenhuizen L. 1990: "The effect of
various levels of ractopamine hydrochloride on the performance and
carcass characteristics of finishing swine." J Anim. Sci. 68:
3588-3595; Williams N. H.; Cline T. R.; Schinkel A. P. and Jones D.
J. 1994: "The impact of ractopamine, energy intake and dietary fat
on finisher pig growth performance and carcass merit." J. Anim.
Sci. 72:
[0137] 3152-3162; Mills S. E.: 2001: "Biological Basis of
Ractopamine Response." J.
[0138] Anim. Sci. 79 (Suppl.1): E28-32; Marchant-Forde J. N., Lay
D. C., Pajor E. A., Richert B. T., Schinckel A. P.: The effects of
ractopamine on the behavior and physiology of finishing pigs. J
Anim Sci. 2003, 81: 416-422 which publications are all hereby
included in their entirety by reference.
[0139] To those skilled in the art of pharmacology, it is known
that synthetic adrenergic beta-receptor agonists have numerous
effects, that may have similarities to endogenous adrenergic
beta-receptor agonists, of which adrenaline and noradrenaline are
the most well known.
[0140] Three types of adrenergic beta-receptors have been
described: Stimulation of beta-1 receptors leads--for example--to
increased heart rate, increased cardiac contractility and increased
blood pressure. Stimulation of adrenergic beta-2 receptors
leads--for example--to relaxation of various types of smooth
muscles, such as bronchial smooth muscle. Adrenergic
beta-3-adrenergic receptors are--for example--involved in the
regulation of lipolysis and thermogenesis. The binding of an
agonist to a receptor does not always induce a signalling event and
it is possible that an isomer may have affinity for a receptor-type
without causing an increase in cyclic AMP in some organ, which may
be caused by various factors, as known to those skilled in the art
of pharmacology.
[0141] Adipose tissue has adrenergic beta-1, beta-2 and beta-3
receptors and stimulation of these receptors usually leads to
lipolysis, which means that fat molecules are broken down.
Stimulation of beta-receptors has also been shown to inhibit
lipogenesis, which means that stimulation of these receptors can
inhibit the formation of fat. Adrenergic beta-receptor stimulation
is also known to increase muscle mass by a mechanism that is
believed to involve inhibition of protein breakdown in the
continuously ongoing process of formation and degradation of muscle
proteins (Bardsley R G, Allcock S M J, Dawson J M, Dumelow N W,
Higgins J A, Lasslett Y V, Lockley A K, Buttery P J Effect of
.beta.-agonists on expression of calpain and calpastatin activity
in skeletal muscle. Biochimie, 1992, 74:267-273, which publication
is hereby included in its entirety by reference.) Other mechanisms
for the increase in muscle mass have been suggested and involve an
induction of increased synthesis of proteins by adrenergic
beta-receptor agonists. Thus, stimulation of adrenergic
beta-receptors at various locations in the body will lead to
decreased fat deposits and increased muscle mass.
[0142] Racemic ractopamine stimulates adrenergic beta-1 and beta-2
receptors, but neither racemic ractopamine nor any of the
ractopamine isomers had affinity for adrenergic beta-3 receptors in
the present studies.
[0143] In receptor binding studies, it has now been found that
RR-ractopamine has the highest affinity for adrenergic
beta-receptors among the four ractopamine isomers. RR-ractopamine
is also having higher affinity for adrenergic beta-1 and beta-2
receptors than found for the racemic mixture of all four isomers.
Also, the effects of the enantiomeric pairs RR/SS and RS/SR were
less than that of RR-ractopamine. Interesting and important
advantages of receptor selectivity by RR-ractopamine were
found.
[0144] Those skilled in the art of pharmacology avoid linking of in
vivo activity of adrenergic beta-agonists directly to receptor
affinity of drugs, since the ultimate effects in vivo depend not
only on receptor affinity, but also on the availability and
composition of the available receptor population in various organs.
The complicated situation in various organs can be exemplified with
the availability of .beta.-1 and .beta.-2 receptors in the human
heart, where, under normal circumstances, the distribution of
adrenergic beta-receptors are approximately 77% .beta.-1
receptors+23% .beta.-2 receptors.
[0145] Adrenergic receptor populations can change under various
circumstances and during heart failure the human heart has less
.beta.-1 receptors than normal, and as a result the beta-receptor
population in the failing heart consists of about 60% .beta.-1
receptors+about 40% .beta.-2 receptors (Bristow M R, Ginsburg R,
Umans V, Fowler M, Minobe W, Rasmussen R, Zera P, Menlove R, Shah
P, Jamieson S, Stinson E. .beta.-1 and .beta.-2 adrenergic receptor
subpopulations in nonfailing and failing human ventricular
myocardium. Circ Res 1986, 59: 297-309, which publication is hereby
included in its entirety by reference.) Thus a combined
beta-1/beta-2 receptor agonists may have advantages over a
selective beta-1 or a selective beta-2 agonist. Adrenergic
beta-receptors may also be down-regulated in selected organs upon
repeated stimulation with an adrenergic agonist. The term
"down-regulated" refers to the fact that individual receptors seem
to disappear from the cell membrane, probably by internalisation
into the cell. A decreased beta-receptor density by beta-adrenergic
stimulation was described by Spurlock et al., who found that the
concentration of adrenergic beta-receptors in adipose tissue could
be reduced by 50% by exposing animals to racemic ractopamine.
(Spurlock M E, Cusumano J C, Ji Q, Anderson D B, Smith-II C K,
Hancock D L, Mills S E. The effect of ractopamine on
.beta.-adrenoceptor density and affinity in porcine adipose and
skeletal muscle tissue. J. Anim, Sci. 1994, 72:75-80, which
publication is hereby included in its entirety by reference.)
[0146] The following studies have been initiated by us and are
performed in laboratory animals under our close supervision:
EXAMPLE 1
[0147] Neuropharmacological profile studies are performed in
laboratory animals (Irwin test) being repeatedly administered the
test articles orally. Racemic ractopamine produced increased stress
in the animals, thereby supporting the findings of Marchant-Forde
et al. (Marchant-Forde J. N., et. al. 2003: "The effects of
ractopamine on the behaviour and physiology of finishing pigs" J
Anim Sci., 81: 416-422 and hereby included in its entirety by
reference). Surprisingly the pure RR-isomer of ractopamine did not
cause stress in this study. In the present Irwin tests, there was
no stress by a reference compound (R-salbutamol; Cipla Batch
#HX0247; gift from Dr. Y. Hamied) that is known not to cause stress
in livestock animals (London et al., 2005), thereby validating the
test methodology.
EXAMPLE 2
[0148] Results from ongoing stress testing of RR-ractopamine,
racemic ractopamine and R-salbutamol in mice using the methodology
described by Aberg (U.S. Pat. No. 6,372,799) demonstrate
CNS-mediated stress in animals treated with racemic ractopamine,
while surprisingly, RR-ractopamine is not causing stress. Other
isomers and enantiomeric pairs of ractopamine are studied using
this methodology.
EXAMPLE 3
[0149] Spontaneous motor activity studies in mice being
administered test articles orally, were part of the Irwin tests
(Example 1, above). As known by those skilled in the art, increased
stress will produce increased spontaneous motor activity in mice.
There were no statistically significant effects of RR-ractopamine
on spontaneous motor activity in these studies.
EXAMPLE 4
[0150] Airway smooth muscle tissues were contracted by carbachol.
The inhibitory effects of isomers, enantiomeric pairs and a racemic
mixture of ractopamine are being investigated.
[0151] Conclusions (from ongoing studies): RR-ractopamine, but not
SS-ractopamine demonstrates potent airway smooth muscle relaxing
activity. The very weak activity of SS-ractopamine in this study is
probably due to optical impurities of (a) more potent isomer(s)
and/or to a weak intrinsic activity of SS-ractopamine. Racemates of
ractopamine are significantly less active than RR-ractopamine. Test
results from these functional studies verify and support the
results from the receptor binding studies.
EXAMPLE 5
[0152] Metabolic studies are being performed using hepatocytes and
liver microsomes. Preliminary results indicate that the RR-isomer
is metabolised at a higher rate than the SS-isomer. The metabolic
rate of all single isomers, the two enantiomeric pairs and the
racemic mixture of all isomers are being studied.
[0153] Conclusions from current biological tests: Racemic
ractopamine is causing symptoms that are indicative of CNS-mediated
stress, while it has surprisingly been found the pure RR-isomer of
ractopamine does not cause CNS-mediated stress in animals at
dose-levels that are equivalent to therapeutic dose levels in vivo
in livestock animals.
[0154] It is concluded from tests on bronchial smooth muscle--an in
vitro model of bronchoconstriction in horses, suffering from
heaves--that RR-ractopamine is a potent bronchodilator, useful in
horses suffering from heaves.
[0155] Although the present invention has been described with
reference to certain preferred embodiments, it will be appreciated
that many variations and modifications may be made within the scope
of the broad principles of the invention. Hence, it is intended
that the preferred embodiments and all of such variations and
modifications be included within the scope and spirit of the
invention, as defined by the claims.
REFERENCES
[0156] The following publications and patents are hereby included
in their entirety by reference.
[0157] Anderson D. B. and Veenhuizen L: The effect of various
levels of ractopamine hydrochloride on the performance and carcass
characteristics of finishing swine. J Anim. Sci. 1990, 68:
3588-3595.
[0158] Bardsley R G, Alcock S M J, Dawson J M, Dumelow N W, Higgins
J A, Lasslett Y V, Lockley A K, Buttery P J: Effect of
.beta.-agonists on expression of calpain and calpastatin activity
in skeletal muscle. Biochimie, 1992, 74:267-273.
[0159] Boissy, A, Bouissou, M-F: Assessment of individual
differences in behavioural reactions to heifers exposed to various
fear-eliciting situations. Applied Animal Behaviour Science 1995,
46:17-31.
[0160] Bristow M R, Ginsburg R, Umans V, Fowler M, Minobe W,
Rasmussen R, Zera P, Menlove R, Shah P, Jamieson S, Stinson E:
.beta.-1 and .beta.-2 adrenergic receptor subpopulations in
nonfailing and failing human ventricular myocardium. Circ Res 1986,
59: 297-309.
[0161] Eliel et al.: Stereochemistry of Carbon Compounds, Mc Graw
Hill, 1962.
[0162] Chatillon G: Transport mortality has its origin in stress:
how to get pigs to their destination in good condition. Porc.
Magazine 1994, 265: 37-41.
[0163] Colbert W E, Williams P D, Williams G D: Beta-adrenoceptor
profile of ractopamine HCl in isolated smooth muscle and cardiac
muscle tissues of rat and guinea pig, J Pharm Pharmacol 1991, 43:
844-847.
[0164] Goodman-Gilman, The Pharmacological Basis of Therapeutics.
9th Ed., McGraw-Hill 1996. ISBN 0-07-026266-7.
[0165] Grandin, T (1993), Behavioural agitation during handling of
cattle is persistent over time. Applied Animal Behaviour Science
1993, 36:1-9.
[0166] International Egg and Poultry Revue, USDA, Aug. 2, 2005.
www.ams.usda.gov/poultry/mncs/InternationalPoultryandEgg/2005Reports/x080-
205.pdf
[0167] London C J, Aberg G., Sadler M., Marchant-Forde J N: Effects
of a New Growth Promoter (R-albuterol) for Commercial Swine
Production. Abstr. Bio2005, Philadelphia, US. June 2005.
[0168] Marchant-Forde J. N., Lay D. C., Pajor E. A., Richert B. T.,
Schinckel A. P.: The effects of ractopamine on the behavior and
physiology of finishing pigs. J Anim Sci. 2003, 81: 416-422.
[0169] Merck Index, 1996, 12: Ractopamine; pages 1392-1393.
[0170] Mills S E: Biological Basis of Ractopamine Response. J.
Anim. Sci. 2001, 79 (suppl1): E28-32.
[0171] Mills S E, Kissel J, Bidwell C A, Smith D J:
Stereoselectivity of porcine .beta.-adrenergic receptors for
ractopamine stereoisomers. J. Anim. Sci. 2003, 81: 122-129.
[0172] Mills S E, Spurlock M E, Smith D J: Beta-adrenergic receptor
subtypes that mediate ractopamine stimulation of lipolysis. J.
Anim. Sci. 2003, 81: 662-668.
[0173] National Research Council. 1990. Metabolic
modifiers--Effects on the nutrient requirements of food-producing
animals. National Academy of Sciences, Washington D.C., USA.
[0174] Odeh F M, Cadd G G, Satterlee D G: Genetic characterization
of stress responsiveness in Japanese quail. Poult Sci. 2003, 82:
31-35.
[0175] Post J, Rebel J M J, ter Huurne A A: Physiological Effects
of Elevated Plasma Corticosterone Concentrations in Broiler
Chicken. An Alternate Means by which to Assess the Physiological
Stress. Poultry Science, 2003, 82:1313-1318.
[0176] Ricke E A, Smith D J, Feil V J, Larsen G L, Caton J S
Effects of ractopamine HCl stereoisomers on growth, nitrogen
retention and carcass composition in rats. J. Anim, Sci.1999. 77:
701-707.
[0177] Shappell, N. W., Feil V. J., Smith D. J., Larsen G. L.,
McFarland D. C.: Response of C2C12 mouse and turkey skeletal muscle
cells to the beta-adrenergic agonist ractopamine. J. Anim. Sci.
2000, 78: 699-708.
[0178] Spurlock M E, Cusumano J C, Ji Q, Anderson D B, Smith-II C
K, Hancock D L, Mills S E. The effect of ractopamine on
.beta.-adrenoceptor density and affinity in porcine adipose and
skeletal muscle tissue. J. Anim, Sci. 1994, 72: 75-80.
[0179] Stadler K,: Porcine Stress Syndrome and Its Effects on
Maternal, Feedlot and Carcass Quantitative and Qualitative Traits.
The University of Tennessee, Agricultural Extension Service, PB
1606.
[0180] Thompson, M J; Huss, P; Unverferth, M D; Fasola A; Leier, C
V: Hemodynamic effects of intravenous butopamine in congestive
heart failure. Clin Pharmacol Ther, 1980, 28: 324-334.
[0181] Sterle J.: The Frequency of The Porcine Stress Gene in Texas
Show Pigs. http://animalscience.tamu.edu.
[0182] Van Dijk J. and Moed H. D. in Recueil des Traveaux
Chimiques, 1973, 92: 1281-1297.
[0183] Warris P D, Brown S N, Adams S J M. Relationship between
subjective and objective assessment of stress a slaughter and meat
quality in pigs. Meat Science 1994, 38:329-340.
[0184] Watkins L E, Jones D H, Mowrey D H, Anderson D B, Veenhuizen
L. The effect of various levels of ractopamine hydrochloride on the
performance and carcass characteristics of finishing swine. J.
Anim. Sci. 1990.68: 3588-3595.
[0185] Wilen, S A, Lochmuller, L H et al., 1975, J. Chromatogr.
113(3): 283-302.
[0186] Williams N H, Cline T R, Schinkel A P, Hones D L: The impact
of ractopamine, energy intake and dietary fat on finisher pig
growth performance and carcass merit. J. Anim. Sci. 1994, 72:
3152-3162.
[0187] EP 7,205
[0188] U.S. Pat. No. 4,690,951
[0189] U.S. Pat. No. 5,057,427
[0190] U.S. Pat. No. 5,077,217
[0191] U.S. Pat. No. 5,643,967
[0192] U.S. Pat. No. 6,372,799
[0193] U.S. Pat. No. 6,855,334
[0194] U.S. Pat. No. 6,974,587
[0195] WO 2006/064283 A1
* * * * *
References