U.S. patent application number 09/788198 was filed with the patent office on 2001-11-08 for use of alpha1a adrenoceptor agonists with alpha1b and alpha1d antagonism for the treatment of stress urinary incontinence.
Invention is credited to Brioni, Jorge D., Brune, Michael E., Buckner, Steven A., Kolasa, Teodozyj, Sullivan, James P..
Application Number | 20010039255 09/788198 |
Document ID | / |
Family ID | 26879192 |
Filed Date | 2001-11-08 |
United States Patent
Application |
20010039255 |
Kind Code |
A1 |
Brioni, Jorge D. ; et
al. |
November 8, 2001 |
Use of alpha1A adrenoceptor agonists with alpha1B and alpha1D
antagonism for the treatment of stress urinary incontinence
Abstract
The following disclosure relates to a method of treating
incontinence with a compound having a specific .alpha..sub.1A
adrenoceptor profile.
Inventors: |
Brioni, Jorge D.; (Vernon
Hills, IL) ; Brune, Michael E.; (Mundelein, IL)
; Buckner, Steven A.; (Wadsworth, IL) ; Kolasa,
Teodozyj; (Lake Villa, IL) ; Sullivan, James P.;
(Deerfield, IL) |
Correspondence
Address: |
Steven F. Weinstock
Abbott Laboratories
AP6D/D-377
100 Abbott Park Road
Abbott Park
IL
60064-6050
US
|
Family ID: |
26879192 |
Appl. No.: |
09/788198 |
Filed: |
February 16, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60183498 |
Feb 17, 2000 |
|
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Current U.S.
Class: |
514/1 |
Current CPC
Class: |
A61K 31/4174 20130101;
A61K 31/00 20130101 |
Class at
Publication: |
514/1 |
International
Class: |
A61K 031/00 |
Claims
What is claimed:
1. A method of treating stress urinary incontinence by
administering a compound that is an .alpha..sub.1A adrenoceptor
agonist and an .alpha..sub.1B antagonist.
2. A method of claim 1 wherein said compound is an .alpha..sub.1D
antagonist.
3. A method of claim 1 wherein said .alpha..sub.1B antagonism is
competitive.
4. A method of claim 1 wherein said .alpha..sub.1B antagonism is
non-competitive.
5. A method of claim 1 wherein said compound has an IUP (5
mmHg)/MAP (20 mmHg) selectivity ratio of 5 or greater.
6. A method of claim 1 wherein said compound has an IUP (5
mmHg)/MAP (20 mmHg) selectivity ratio of 10 or greater.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application is a conversion of U.S. Provisional
Application No. 60/183,498, filed on Feb. 17, 2000.
TECHNICAL FIELD
[0002] The present invention discloses a novel approach in the
treatment of stress urinary incontinence. More specifically, this
invention provides a method of treating urinary incontinence by
administering selective .alpha..sub.1A adrenoceptor agonists with
antagonistic properties at the .alpha..sub.1B and .alpha..sub.1D
subtypes.
BACKGROUND OF THE INVENTION
[0003] Urinary incontinence is a condition defined as the
involuntary loss of urine and was recently classified as a disease
by the World Health Organization. Involuntary loss of urine occurs
when pressure inside the bladder exceeds the retentive pressure of
the urethral sphincters (intraurethral pressure). The disease may
arise from different pathological, anatomical and neurological
factors. Three major types of urinary incontinence have been
defined based on symptoms, signs and condition: stress, urge and
mixed incontinence.
[0004] Stress urinary incontinence (SUI) is the involuntary loss of
urine during coughing, sneezing, laughing, or other physical
activities that increase intra-abdominal pressure in the absence of
a bladder contraction. SUI is most common in women between the ages
of 25 and 50, and up to 47% of regularly exercising women have some
degree of SUI.
[0005] The most common causes of SUI in women are urethral
hypermobility and intrinsic urethral sphincter deficiency. Urethral
hypermobility is characterized by a weakness of the pelvic floor
support. Because of this weakness, there is rotational descent of
the bladder neck and proximal urethra during increases in abdominal
pressure. If the urethra opens concomitantly, SUI may ensue.
Intrinsic urethral sphincteric deficiency denotes a dysfunction of
the urethral smooth and striated muscle support system. This may
have congenital origins, or may be acquired after surgery, trauma,
or a sacral cord lesion. In females, intrinsic urethral sphincter
deficiency is commonly associated with multiple incontinence
surgical procedures, as well as hypoestrogenism, aging or both. In
this condition, the urethral smooth muscle and sphincter is unable
to generate enough resistance to retain urine in the bladder,
especially during the stress maneuvers. It is believed that a
number of patients suffer from both urethral hypermobility and
intrinsic urethral sphincter deficiency.
[0006] The present methods to treat SUI include physiotherapy and
surgery. Treatment with pharmaceutical agents is limited to the use
of non-selective adrenergic agonists like phenylpropanolamine and
midodrine. The rationale for the use of adrenergic agonists for the
treatment of SUI is based on physiological data indicating an
abundant noradrenergic input to smooth muscle of the urethra.
Studies in rats, cats and dogs indicate that sympathetic adrenergic
input to the urethra is tonically active during bladder filling to
promote urine storage and that surgical or pharmacological blockade
of the sympathetic pathways can reduce urethral resistance.
[0007] Substantial preclinical physiological, pharmacological and
molecular evidence suggests that .alpha..sub.1A adrenoceptors are
responsible for mediating the effects of norepinephrine on urethral
tone. Receptor binding and autoradiographic studies have revealed
the existence of .alpha..sub.1 adrenoceptors in human, rabbit and
dog urethra (Chapple C, Aubry M, James S, Greengrass P, Burnstock
G, Turner-Warwick R, Milroy E and Davey M (1989). Characterisation
of human prostatic adrenoceptors using pharmacology receptor
binding and localization. British Journal of Urology 63: 487-496;
Testa R, Guarnieri L, Ibba M, Strada G, Pogessi E, Taddei C,
Simonazzi I and Leonardi A (1993). Characterization of alpha-1
adrenoceptor subtypes in prostate and prostatic urethra of rat,
rabbit dog and man. European Journal of Pharmacology 249: 307-315;
Nishi K, Latifpour J, Saito M, Foster H, Yoshida M and Weiss R
(1998). Characterization, localization and distribution of .alpha.1
adrenoceptor subtype in male rabbit urethra. Journal of Urology
160: 196-205), and in vitro studies demonstrated that the
.alpha..sub.1 receptors regulate urethral tone as phenylephrine can
contract isolated urethral strips from several animal species
(Bridgewater M, MacNeil H and Brading A (1993). Regulation of tone
in pig urethral smooth muscle. Journal of Urology 150: 223-228;
Chess-Williams R, Aston N and Couldwell C (1994).
.alpha.1A-adrenoceptor subtype mediates contraction of the rat
urethra. Journal Autonomic Pharmacology 14: 375-381). Isolated
strips of human urethral muscle also contract in response to
.alpha..sub.1 adrenoceptor agonists, a response that is blocked by
.alpha..sub.1 antagonists like prazosin (Brading A, Fry C, Maggi C,
Takeda M, Wammack R, Wicklund N, Uvelius B and Gabella G (1998).
Incontinence: Cellular Biology. In: Incontinence (Eds. Abrams P,
Khoury S and Wein A), pp. 59-104, Monaco; Chapple 1989). Similarly,
systemic injections of epinephrine increase intraurethral pressure
in anesthetized dogs, an effect also blocked by prazosin (Sommers
W, Felsen D, Chou T, Marion D, Chernesky C and Darracott-Vaughan E
(1989). An in vivo evaluation of alpha adrenergic receptors in
canine prostate. Journal of Urology 141: 1230-1233).
[0008] Adrenoceptors are cell membrane receptors belonging to the
heptahelical G-protein family of receptors (GPCRs) that respond to
the physiological agonists, norepinephrine and epinephrine (Hancock
A (1996). .alpha.1 adrenoceptor subtypes: A synopsis of their
pharmacology and molecular biology. Drug Development Research 39:
54-107). They are divided into 3 families: .alpha..sub.1,
.alpha..sub.2 and .beta.. Although .alpha. adrenoceptors were
originally subclassified into ".alpha..sub.1 postsynaptic" and
".alpha..sub.2 presynaptic", this purely anatomical classification
was later abandoned and defined based on the pharmacology and the
molecular biology of the cloned receptors (Langer S (1999). History
and nomenclature of .alpha.1-adrenoceptors. European Urology 36:
2-6). Six genes have been identified and sequenced to support the
present classification: .alpha..sub.1a, .alpha..sub.1b,
.alpha..sub.1d, .alpha..sub.2a, .alpha..sub.2b, and .alpha..sub.2c
(as recommended by IUPHAR, lowercase subscripts designate the
cloned subtypes, and uppercase subscripts define the
pharmacologically defined subtypes). The elucidation of the
molecular diversity of adrenoceptors has provided a molecular
correlate to earlier pharmacological studies. The use of subtype
specific probes has shown that the human, dog and rabbit urethra
are enriched with mRNA for the .alpha..sub.1A adrenoceptor, and
RNAase protection assays indicated that the .alpha..sub.1A subtype
is the predominant subtype in human urethra.
[0009] Clinical studies with the non-selective .alpha. adrenoceptor
agonists, PPA and midodrine have demonstrated limited clinical
efficacy. The use of PPA has been limited by concerns regarding
dose-limiting side effects, particularly hypertension, that have
curtailed the ability to evaluate the compound at higher doses. PPA
is a non-selective adrenergic agonist lacking selectivity for
.alpha..sub.1 adrenoceptors in tissue bath studies. Several patents
like EP 887,346; EP 538,469 and U.S. Pat. No. 5,610,174 disclose
compounds that are claimed as selective .alpha..sub.1A adrenoceptor
agonists.
[0010] Adrenergic receptors in the vascular bed regulating blood
pressure are presumed to be mainly of the .alpha..sub.1B subtype.
Adrenergic antagonists (like prazosin and terazosin) reduce blood
pressure in Spontaneously Hypertensive rats (SHRs) with a potency
ranking that correlates with their potency to displace binding to
the .alpha..sub.1b receptor but not the .alpha..sub.1a receptor
(Hancock 1996), and a reduced hypertensive response to
phenypephrine has been observed in .alpha..sub.1b knock-out mice
(Cavalli A, Lattion A, Hummler E, Nonniger M, Pedrazzini T, Aubert
J, Michel M, Yang M, Lembo G, Vecchione C, Mostardini M, Schmidt A,
Beerman F and Cotecchia S (1997). Decreased blood pressure response
in mice deficient of the .alpha.1b-adrenergic receptor. Proceedings
of the National Academy of Sciences USA 94: 11589-11594). However,
there is recent data to suggest that .alpha..sub.1A receptors may
also exist extra-synaptically in the vasculature, and while such
receptors may not be involved in the normal regulation of blood
pressure they may respond to exogenous .alpha..sub.1A agonists.
Based on these data, the .alpha..sub.1B antagonist attributes may
reduce the hypertensive liability of the .alpha..sub.1A adrenergic
agonists.
[0011] The .alpha..sub.1 receptors in the bladder are mainly the
.alpha..sub.1D subtype. Adrenergic antagonists like prazosin
decrease bladder hyperreflexia and increase bladder capacity
(Andersson K (1999). .alpha.1-adrenoceptors and bladder function.
European Urology 36: 96-102). In view of these clinical findings,
.alpha..sub.1D antagonism may provide additional benefit to
patients with mixed incontinence.
[0012] There continues to be a need for medicaments that are useful
for treating incontinence. A compound having the desired
.alpha..sub.1A agonist and .alpha..sub.1B and preferably
.alpha..sub.1D antagonist profile may be useful in treating
incontinence.
SUMMARY OF THE INVENTION
[0013] The present invention provides a method of treating stress
urinary incontinence by providing to the subject a compound having
.alpha..sub.1A adrenoceptor agonistic properties as well as
antagonistic properties at .alpha..sub.1B and preferably
.alpha..sub.1D adrenoceptors.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1: Demonstrates the effect of phenylpropanolamine on
intraurethral pressure (IUP) and mean arterial pressure (MAP) in
dogs after i.v. administration of the compound.
[0015] FIG. 2: Demonstrates the effect of A-61603 on intraurethral
pressure (IUP) and mean arterial pressure (MAP) in dogs after i.v.
administration of the compound.
[0016] FIG. 3: Demonstrates the effect of A-286569 on intraurethral
pressure (IUP) and mean arterial pressure (MAP) in dogs after i.v.
administration of the compound.
[0017] FIG. 4: Demonstrates the effect of A-286569 on intraurethral
pressure (IUP) and mean arterial pressure (MAP) in dogs after i.v.
administration of the compound.
DETAILED DESCRIPTION OF THE INVENTION
[0018] All references cited within this document are hereby
incorporated by reference.
[0019] The present invention provides a method of treating stress
urinary incontinence by administering selective .alpha..sub.1A
adrenoceptor agonists with .alpha..sub.1B and preferably
.alpha..sub.1D antagonistic properties. The invention provides a
method of inducing contraction of the urethra and bladder neck via
the effect of administering a compound that is a .alpha..sub.1A
adrenoceptor agonist, and also provide a method to block
.alpha..sub.1B adrenoceptors present in the vascular tissue and
also preferably block .alpha..sub.1D adrenoceptor in the bladder.
One of the goals of the present invention is to provide a means for
developing compounds for treating incontinence by getting better
separation in intrauretheral pressure versus mean arterial
pressure. Preferably compounds have an IUP (5 mmHg)/MAP (20 mmHg)
selectivity ratio of 5 or greater. More preferably, compounds have
an IUP (5 mmHg)/MAP (20 mmHg) selectivity ratio of 10 or
greater.
[0020] Pharmacological treatment of stress urinary incontinence is
presently focused on the use of non-selective .alpha. agonists or
by using selective .alpha..sub.1A adrenoceptor agonists. These type
of compounds may induce an increase in mean arterial pressure that
limits the therapeutic use of present drugs. The use of compounds
having .alpha..sub.1A adrenoceptor agonistic activity together with
.alpha..sub.1B antagonistic properties may provide a superior
urethral-vascular selectivity. The .alpha..sub.1B antagonism may
reduce the potential hypertensive side-effects. Administration of a
compound exhibiting .alpha..sub.1B antagonism may provide
additional benefit by ameliorating the constriction of vascular
tissue typically associated with the use of non-selective .alpha.
agonists. It is to be understood that the compounds having the
desired profile may be administered by oral, intravenous,
subcutaneous, and intramuscular means.
[0021] Quantitative analysis of agonist and antagonist action is
the basis of receptor classification and drug design. When an
"agonist" binds to a compatible receptor it forms an
agonist-receptor complex and initiates a second messenger event
resulting in either contraction of smooth muscle or relaxation
depending on the receptor type and or location. The interaction of
an agonist with a receptor may be characterized by two quantities,
affinity and efficacy. These quantities can be estimated by
generating two concentration response curves and fitting the data
to a four parameter curve smoothing routine. The first curve is a
reference standard followed by a thorough rinsing and a second
curve generated using the test agent. From this data the affinity
(potency) described as an EC.sub.50 (half maximum response) can be
determined. Agonist potency (pD.sub.2) is expressed as the negative
log10 of the EC.sub.50. The efficacy is determined by comparing the
maximum value of the test agent to the maximum value of the
reference agent and expressed as a % of maximum response. For
purposes of this disclosure, agonists which exhibit less than 25%
agonism as compared to phenylephrine are not considered
agonists.
[0022] Conversely, an "antagonist" blocks the receptor from binding
to an agonist and therefore prevents intracellular responses which
lead to contraction of smooth muscle or relaxation depending on the
receptor type and or location. The interaction of an antagonist
with a receptor can be characterized by an affinity constant,
pA.sub.2. The affinity unit, pA.sub.2, can be defined as negative
logarithm to base 10 of the molar concentration of antagonist drug
that will reduce the effect of the reference agonist by 50%. Three
analytical criteria that competitive antagonists possess should be
satisfied. The fractional increase in agonist concentration
required to overcome the effects of the antagonist should be
independent of the agonist concentration. Secondly, the affinity of
the antagonist should be independent of concentration, therefore
the Schild plot should have a slope of unity. Thirdly, the
antagonist affinity should be independent of the agonist used.
Agents that show a slope of unity in the Schild plot are considered
competitive antagonists of that particular receptor subtype,
whereas agents that show a slope different from unity are
considered non-competitive antagonists (Schild, H.O. (1947). pA, A
new scale for the measurement of drug antagonism. Br. J. Pharmacol.
2, 189-206). For purposes of this disclosure, antagonists are not
considered antagonists if they exhibit less than 25% blockade of
phenylephrine agonism.
[0023] Biological Assays
[0024] Rabbit Urethra .alpha.1A Subtype
[0025] Female New Zealand white rabbits (1.75-3.5 kg) were
sacrificed by means of an I.P. injection of pentobarbital solution,
0.5 ml/kg, Somlethal.RTM., J. A. Webster Inc., Sterling Mass. The
urethra was removed with the urinary bladder and immediately placed
into Krebs Ringer bicarbonate solution with the following mM
concentrations: 120 NaCl, 18.0 NaHCO.sub.3, 11.0 dextrose, 4.7 KCl,
2.5 CaCl.sub.2, 1.5 MgSO.sub.4, 1.2 KH.sub.2PO.sub.4 and
equilibrated with 5% CO.sub.2: 95% O.sub.2. The pH was adjusted to
7.2 at 25.degree. C. by titrating with a saturated solution of
NaHCO.sub.3. The pH increased to 7.4 at 37.degree. C. Propranolol
(0.004 mM) was included in all of the assays to block
.beta.-adrenoceptors. The urethra was separated from the bladder
and cut into 4 tissue rings approximately 3-4 mm wide. One end was
fixed to a stationary glass rod and the other to a Grass FT03
transducer at a basal preload of 1.0 g of tension. Data was
recorded on a Grass model-7 polygraph. Tissues were rinsed every 10
minutes for a total of 45-60 minutes. The urethra was primed once
with 80 mM KCl, rinsed to basal tension and again with 10 .mu.M
phenylephrine (PE). After an additional 60 minute equilibration
period a reference concentration response curve was generated for
each tissue using PE as the reference agonist. A cumulative
concentration protocol was employed. Following a 75 minute washout
period a second response curve was then generated in the same
fashion using the test agent. The amount of agent necessary to
cause a 50% response (ED.sub.50) was calculated using "AGANTG"
(Zielinski, P. J., Buckner, S. A. (1998). AGANTG: A Microsoft Excel
5.0-visual basic routine for the analysis of dose-response data.
Analyst. 123, 1661-1668), a four parameter curve fitting program
similar to "Allfit" (DeLean, A., Munson, P. J., Rodbard, D. (1980).
Simultaneous analysis of families of sigmoidal curves: application
to bioassay, radioligand assay, and physiological dose-response
curves. Am. J. Physiol. 235, E97-102). Agonist potencies were
indexed to PE and expressed as the negative logarithm (pD.sub.2).
Each tissue was used for only one test agonist. For antagonists,
the test agent was allowed a 30 minute exposure time before a
second PE curve was started. The potency, expressed as a pA.sub.2,
was calculated according to the method of Arunlakshana, O., Schild,
H. O. (1959), Some quantitative uses of drug antagonists. Br. J.
Pharmacol. 14, 48-58. The individual tissues were exposed to only
one concentration of the test antagonist. The regression lines of
the Schild plots were analyzed using least squares regression
(Snedecor, G. W., Cochran, W. G., (1980). In Statistical methods,
7.sup.th edition, Iowa State University Press, Ames, Iowa).
[0026] Rat Spleen .alpha.1B Subtype
[0027] Male Sprague Dawley rats (150-200 g) were sedated with
CO.sub.2 and decapitated. The entire spleen was removed and
immediately placed into Krebs Ringer bicarbonate solution as
described above. The spleen was split longitudinally into two
preparations per rat. One end was fixed to a stationary glass rod
and the other to a Grass FT03 transducer at a basal preload of 1.0
g (Aboud R, Shafli M and Docherty JR (1993). Investigation of the
subtypes of alpha-1-adrenoceptors mediating contractions of rat
aorta, vas deferens, and spleen. Br J Pharmacol 109:80-87).
Experimental protocol and data analysis was performed as described
above followed.
[0028] Rat aorta .alpha.1D Subtype
[0029] Male Sprague Dawley rats (350-450 g) were sedated with
CO.sub.2 and decapitated. The entire thoracic aorta was removed and
immediately placed into Krebs Ringer bicarbonate solution as
described above. The aorta was cleaned of extraneous tissue and the
endothelium removed by passing a 100 mm length of PE-160 tubing
through the lumen. The aorta was cut into 3-4 mm rings and mounted
in 10 ml isolated tissue baths at 37.degree. C. The aorta from each
rat could supply 8 tissue rings. One end was fixed to a stationary
glass rod and the other to a Grass FT03 transducer at a basal
preload of 1.0 g. Absence of functional endothelium was confirmed
by loss of the acetylcholine-induced (10 .mu.M) relaxation
performed at the end of the PE prime step. Experimental protocol
and data analysis was performed as described above. 1
[0030] Radioligand Binding Ki (nM)
[0031] Compounds (PPA, A-61603, A-286666, and A-286569) were
evaluated in radioligand binding assays specific for .alpha..sub.1A
(rat submaxillary gland), .alpha..sub.1b (hamster receptor
expressed in mouse fibroblasts) and .alpha..sub.1d (rat receptor
expressed in mouse fibroblasts) using [.sup.3H]-prazosin as the
radioligand as described in Knepper, et al. J. Pharm. Exp. Ther.
(1995), 274, 97-103. The results are shown in Table 1. Radioligand
binding studies indicate that PPA is a weak adrenergic ligand,
while the other compounds show potent binding to the .alpha..sub.1A
subtype, and some show potent binding to the .alpha..sub.1b and
.alpha..sub.1d subtypes.
1 TABLE 1 Compound .alpha..sub.1A (Rat) .alpha..sub.1b (Hamster)
.alpha..sub.1d (Rat) PPA >10,000 >10,000 >10,000 A-61603
15 .+-. 4 1,210 .+-. 257 1557 .+-. 169 A-286666 137 .+-. 15 913
.+-. 135 287 .+-. 41 A-286569 150 .+-. 32 >10,000 840 .+-.
78
[0032] Evaluation of Adrenergic Compounds As Agonists
[0033] The functional activity of the ligands as adrenergic
agonists was evaluated in 3 tissue bath preparations (Table 2)
indicative of .alpha..sub.1A, .alpha..sub.1B and .alpha..sub.1D
subtypes. PPA is a weak agonist at all adrenergic subtypes. A-61603
is an agonist at the 3 subtypes; it is a potent agonist at the
.alpha..sub.1A subtype (pD2=8.0) and shows selectivity towards the
.alpha..sub.1B and .alpha..sub.1D subtype (30-fold or greater).
A-286666 and A-286569 are agonists at the .alpha..sub.1A subtype
(pD2=6.2 and 5.6 respectively), but they are inactive at the
.alpha..sub.1B and .alpha..sub.1D subtypes (showing less than 15%
activity). The efficacy of the compounds are compared as a percent
of phenylephrine (100%) contraction.
2 TABLE 2 .alpha..sub.1A .alpha..sub.1B .alpha..sub.1D pD.sub.2
efficacy pD.sub.2 efficacy pD.sub.2 efficacy PPA 3.7 68% 3.6 34%
4.2 91% A-61603 8.0 88% 6.5 91% 5.6 100% A-286666 6.2 80% inactive
inactive A-286569 5.6 69% inactive inactive
[0034] Evaluation of A-286666 and A-286569 As Antagonists
[0035] Although some of these compounds show binding at the
.alpha..sub.1B and .alpha..sub.1D subtypes, the binding was not
reflected as functional agonism. Therefore, A-286666 and A-286569
were tested as antagonists on these tissue preparations (Table 3).
Studies were conducted in tissue bath assays that determine effect
on .alpha..sub.1B and .alpha..sub.1D adrenergic receptor subtypes.
Once again, phenylephrine was used to generate a contraction curve
and compared to the test compound to see if contraction was blocked
with the test compound. Based on the slope and regression (r)
analysis, it was determined that A-286666 is a competitive
antagonist at the .alpha..sub.1B and .alpha..sub.1D subtypes
(pA2=5.8 and 6.5, respectively). A-286569 behaves as a
non-competitive antagonist at the .alpha..sub.1B receptor and at
the .alpha..sub.1D receptor subtypes, as indicated by the Schild
plot analysis (due to the poor regression correlation).
3 TABLE 3 .alpha..sub.1B .alpha..sub.1D pA.sub.2 slope r pA.sub.2
slope r A-286666 5.8 0.81 0.9 6.5 0.93 0.9 A-286569 4.8 1.3 0.6 5.2
1.1 0.5
[0036] Evaluation of IUP/MAP
[0037] Intraurethral Pressure in Dogs (IUP-MAP Test)
[0038] Female Beagle dogs (Marshall Farms, North Rose, N.Y.)
greater that 2 years of age and weighing between 12 and 15 kg were
used in these studies. At least 2 weeks prior to any agonist
dosing, dogs were instrumented for the chronic measurement of
arterial blood pressure by implanting a telemetry
transducer/transmitter (TA11PA-C40, Data Sciences International,
St. Paul, Minn.) into a carotid artery.
[0039] On the test day, dogs fasted since the previous afternoon
were pre-anesthetized with thiopental sodium 15 mg/kg i.v.
(Pentothal.TM., Abbott) and intubated. Anesthesia was maintained by
allowing the dog to spontaneously breathe a mixture of isoflurane
(2.5 to 3 volume %) and oxygen delivered by a Narkomed Standard
anesthesia system (North American Drager, Telford, Pa.). An
Abbocath-T.TM. i.v. catheter (18-G, Abbott Laboratories, Abbott
Park, Ill.) was inserted into the cephalic vein for the
administration of agonists. A telemetry receiver (RA1310,
DataSciences) was placed under the head of each dog and was
interfaced to a computerized data acquisition system (Modular
Instruments Inc.(MI2), Malvern, Pa.) which allowed for the
continuous calibrated recording of arterial blood pressure which
was electronically filtered to determine its mean value (MAP).
[0040] Intraurethral pressure was monitored using a balloon
catheter technique previously described (Brune et al., Drug
Development Research 34:267-275,1995). Briefly, a 7 Fr catheter
balloon catheter (41224-01, Abbott) was inserted into the urethral
orifice and advanced approximately 15 cm until the tip was well
inside the bladder. The balloon was then inflated with 1 ml of room
air and the catheter slowly withdrawn until resistance
(corresponding to the bladder neck) was evident. The balloon was
then deflated and the catheter withdrawn an additional 2 cm. The
balloon was then reinflated and its catheter port connected to a
Gould Statham P23Dd pressure transducer interfaced to a
computerized data acquisition system (Modular Instruments, Inc.,
Malvern, Pa.) for the measurement of intraurethral pressure (IUP).
The MAP and IUP pressor responses to increasing iv doses of test
agonists were obtained simultaneously. The pressor effects of each
dose were allowed to return to baseline before the next dose was
given. For PPA, eight dogs (n=8) were used while for A-61603,
A-286666, and A-286569, four dogs were used for each agonist
(n=4).
[0041] The dose required to elicit significant and clinically
meaningful changes in IUP (5 mm Hg) relative to the dose required
to elicit a physiologically significant increase in blood pressure
(20 mm Hg) is calculated. Clinical studies have demonstrated a
significant reduction in incontinent episodes in SUI patients after
a 5 mmHg increase in urethral pressure (Collste L and Lindskog M
(1987). Phenylpropanolamine in treatment of female stress
incontinence. Urology 30: 398-403; Wein A (1995). Pharmacology of
incontinence. Urologic Clinics of North America 22: 557-577).
[0042] Evaluation of the Adrenergic Agents In Vivo
[0043] Examples of compounds with improved in vivo uroselectivity
versus PPA and A-61603 are A-286666 and A-286569. IUP and MAP
pressor effects of each agonist dose were expressed as the maximum
net change in each pressure over pre-dose baseline levels.
Subsequently, the effective doses required to produce a 5 mmHg
increase in IUP (IUP ED.sub.5mmHg) and a 20 mmHg increase in MAP
(MAP ED.sub.20mmHg) were estimated from the dose response data from
each dog. Relative urethral versus vascular selectivity of each
agonist in each dog was estimated using a ratio of these respective
potency indices (MAP ED.sub.20mmHg/IUP ED.sub.5mmHg).
[0044] PPA, A-61603, A-286666 and A-286569 caused dose-dependent
increases in both intraurethral pressure and mean arterial pressure
(FIGS. 1-4). However, there were marked differences in urethral
selectivity of these four compounds. While PPA and A-61603 showed
no urethral selectivity versus the vascular bed (0.4 and 1.7,
respectively), A-286666 and A-286569 were the most selective
compounds in the in vivo model (Table 4) as they show 3-fold or
more selectivity ratio. The selectivity ratio was calculated for
each dog and then averaged. This indicated a need for
.alpha..sub.1A adrenoceptor agonist and an .alpha..sub.1B
antagonist action in the body to increase urethral smooth muscle
contraction while avoiding hypertension caused by vascular tissue
contraction. In addition, an .alpha..sub.1D antagonist may provide
antagonistic actions in the bladder.
[0045] Data are expressed as means (.+-.S.E.M) and all doses are in
nmol/kg, i.v.
4 TABLE 4 MAP IUP Selectivity ratio ED20mmHg ED5mmHg MAP ED20/IUP
ED5 PPA 331 .+-. 80 1092 .+-. 384 0.4 A-61603 0.27 .+-. 0.05 0.16
.+-. 0.02 1.7 A-286666 80.4 .+-. 14 12.1 .+-. 1.5 6.5 A-286569
201.6 .+-. 67 41.9 .+-. 6.2 5.6
* * * * *