U.S. patent application number 12/928184 was filed with the patent office on 2011-04-07 for n-alkylcarbonyl-amino acid ester and n-alkylcarbonyl-amino lactone compounds and their use.
Invention is credited to Edward T. Wei.
Application Number | 20110082204 12/928184 |
Document ID | / |
Family ID | 36498694 |
Filed Date | 2011-04-07 |
United States Patent
Application |
20110082204 |
Kind Code |
A1 |
Wei; Edward T. |
April 7, 2011 |
N-alkylcarbonyl-amino acid ester and N-alkylcarbonyl-amino lactone
compounds and their use
Abstract
The present invention generally relates to refreshing, soothing,
and cooling compounds that affect sensory processes. More
particularly, the present invention pertains to certain
N-alkylcarbonyl-amino acid ester as described herein; compositions
and articles comprising such compounds; and methods of treatment,
for example, methods of increasing alertness, and decreasing
fatigue or sleepiness, and alleviating ocular discomforts of
irritation, itch, and pain.
Inventors: |
Wei; Edward T.; (Berkeley,
CA) |
Family ID: |
36498694 |
Appl. No.: |
12/928184 |
Filed: |
December 6, 2010 |
Current U.S.
Class: |
514/529 ;
560/125 |
Current CPC
Class: |
A61P 1/08 20180101; A61P
29/00 20180101; A61P 3/00 20180101; A61P 1/02 20180101; A61P 11/00
20180101; A61P 17/04 20180101; A61P 17/06 20180101; A61P 31/04
20180101; C07C 233/63 20130101; C07B 2200/07 20130101; C07C 2601/14
20170501; A61P 11/14 20180101; A61P 11/06 20180101; A61P 25/34
20180101; C07D 307/33 20130101; A61P 25/00 20180101; A61P 17/00
20180101 |
Class at
Publication: |
514/529 ;
560/125 |
International
Class: |
A61K 31/215 20060101
A61K031/215; C07C 233/63 20060101 C07C233/63; A61P 29/00 20060101
A61P029/00; A61P 17/04 20060101 A61P017/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 23, 2006 |
GB |
PCT/GB2006/001093 |
Claims
1. A towelette containing a compound of Formula (1): ##STR00007##
wherein: R.sub.1 is hydrogen, or a methyl group such that the
carbon atom to which it is attached is in the D-configuration, and
when R.sub.1 is hydrogen, R.sub.2 is isopropyl, and when R.sub.1 is
a methyl group such that the carbon atom to which it is attached is
in the D-configuration, R.sub.2 is a C.sub.1 to C.sub.3 alkyl
group.
2. A compound according to claim 1, which is
(R)-2-[((1R,2S,5R)-2-isopropyl-5-methyl-cyclohexanecarbonyl)-amino]-propi-
onic acid methyl ester.
3. A compound according to claim 1, which is
(R)-2-R(1R,2S,5R)-2-isopropyl-5-methyl-cyclohexanecarbonyl)-amino]-propio-
nic acid ethyl ester.
4. A compound according to claim 1, which is
(R)-2-[((1R,2S,5R)-2-isopropyl-5-methyl-cyclohexanecarbonyl)-amino]-propi-
onic acid isopropyl ester.
5. A compound according to claim 1, which is
(R)-2-[((1R,2S,5R)-2-isopropyl-5-methyl-cyclohexanecarbonyl)-amino]-aceti-
c acid isopropyl ester.
6. The towelette as in claim 1 wherein the compound is present in
the towelette at a liquid concentration of 0.2 to 2 mg/ml.
7. A method of preparing a therapeutic article of manufacture,
comprising: providing a towelette; contacting the towelette with a
compound of Formula (1): ##STR00008## wherein: R.sub.1 is hydrogen,
or a methyl group such that the carbon atom to which it is attached
is in the D-configuration, and when R.sub.1 is hydrogen, R.sub.2 is
isopropyl, and when R.sub.1 is a methyl group such that the carbon
atom to which it is attached is in the D-configuration, R.sub.2 is
a C.sub.1 to C.sub.3 alkyl group.
8. Use of towelette according to claim 7 to alleviate ocular skin
irritation, itch, and/or pain, and/or to increase alertness and to
reduce sleepiness and fatigue.
9. A therapeutic method comprising: contacting a towelette carrying
a compound of Formula (1): ##STR00009## wherein: R.sub.1 is
hydrogen, or a methyl group such that the carbon atom to which it
is attached is in the D-configuration, and when R.sub.1 is
hydrogen, R.sub.2 is isopropyl, and when R.sub.1 is a methyl group
such that the carbon atom to which it is attached is in the
D-configuration, R.sub.2 is a C.sub.1 to C.sub.3 alkyl group. with
the facial skin of a mammal, the contacting sufficient to deliver a
therapeutically effective amount of the formula 1 compound.
10. The method as in claim 9 wherein the therapeutically effective
amount is sufficient to alleviate ocular skin irritation, itch,
and/or pain, and/or to increase alertness and to reduce sleepiness
and fatigue.
Description
RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application 20080227857, filed Mar. 23, 2006, inventor Wei,
entitled "N-Alkylcarbonyl-Amino Acid Ester and
N-Alkylcarbonyl-Amino Lactone Compounds and Their Use",
incorporated by reference.
[0002] This application is related to:
[0003] U.S. Provisional Application No. 60/667,166 filed 29 Mar.
2005;
[0004] U.S. Provisional Application No. 60/683,384 filed 20 May
2005;
[0005] U.S. Provisional Application No. 60/702,505 filed 26 Jul.
2005;
[0006] U.S. patent application Ser. No. 11/203,728 filed 13 Aug.
2005; and
[0007] U.S. Provisional Application No. 60/772,374 filed 9 Feb.
2006;
[0008] the contents of each of which are incorporated herein by
reference in their entirety.
TECHNICAL FIELD
[0009] The present invention generally relates to refreshing,
soothing, and cooling compounds that affect sensory processes. More
particularly, the present invention pertains to certain
N-alkylcarbonyl-amino acid ester and N-alkylcarbonyl-amino lactone
compounds; compositions and articles comprising such compounds; and
methods of treatment, for example, methods of alleviating the
discomforts of irritation, itch, and pain on the skin and on the
ocular surface.
BACKGROUND
[0010] Menthol and menthol-like compounds are used in toiletries,
confectionery, comestibles, and over-the-counter medications as
ingredients to refresh, cool, flavor, counter-irritate, and
anesthetize the skin and mucous membranes of the mouth and upper
airways. Menthol's utility in relief of sensory discomfort is,
however, limited by its short duration of action and by its
multimodal actions on sensory processes--including odor, harshness
of taste, and irritation. The unpleasant effects of menthol can be
easily experienced, for example, when menthol-containing ointments
are brought near the eye surface. The menthol vapors hurt the eye
and causes tearing.
[0011] There is a need for compounds like menthol that refresh,
cool, and soothe the body's surfaces, but without the disadvantages
of odor, irritancy, and most importantly, a short duration of
action. It is important to have compounds that act much longer than
menthol and without irritation.
[0012] About three decades ago, a group of scientists synthesized
over 1200 compounds in an attempt to find cooling agents that had
properties better than menthol. Their results were summarized in a
paper (Watson et al, "New compounds with the menthol cooling
effect," J. Soc. Cosmet. Chem., 29: 185-200, 1978). From this
research, an N-alkyl-cycloalkyl- and an N-alkyl-alkyl carboxamide,
WS-3 and WS-23, were brought to the market and are used as
additives for confectionery, comestibles, (e.g., candy, chewing
gum), and toiletries. In U.S. Pat. No. 4,178,459 (11 Dec. 1979),
Watson et al. described cooling properties of some
N-alkoxycarbonylalkyl-substituted p-menthane-carboxamides.
[0013] None of the compounds currently known to the art have the
potency or duration of action to qualify them as possible
medications for use in disorders of eye discomfort such as itch
(allergic conjunctivitis), pain, and dryness.
SUMMARY OF THE INVENTION
[0014] One aspect of the present invention pertains to certain
N-alkylcarbonyl-amino acid ester compounds, as described
herein.
[0015] Another aspect of the invention pertains to a composition
comprising such a compound and a delivery vehicle (e.g., for
delivering the compound to a human).
[0016] In one embodiment, the delivery vehicle is a towelette.
[0017] In one embodiment, the compound is present in the
composition in an amount of 0.02 to 0.2% wt/vol (0.2 to 2
mg/ml).
[0018] Another aspect of the present invention pertains to use of
such a compound in the manufacture of a medicament for use in a
method of treatment.
[0019] In one embodiment, the treatment is the relief of (e.g.,
alleviation of) ocular irritation, itch, and/or pain (e.g., wherein
the contacting delivers an amount of the compound that is
therapeutically effective for alleviation of irritation, itch,
and/or pain).
[0020] In one embodiment, the treatment is treatment to increase
alertness, or to decrease sleepiness and fatigue (e.g., wherein the
contacting delivers an amount of the compound that is effective to
increase alertness, or to decrease sleepiness and fatigue).
[0021] As will be appreciated by one of skill in the art, features
and preferred embodiments of one aspect of the invention will also
pertain to other aspect of the invention.
[0022] Other advantages and aspects of the invention will be
understood by reading the following detailed description and the
accompanying claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a bar graph showing duration of cooling (hours)
for eight compounds (in order): D-Ala-OEt, D-Ala-OMe, D-Hsl,
Sar-OEt, WS-5, WS-12, WS-3, and (-)-menthol.
DETAILED DESCRIPTION
[0024] A class of compounds that is suitable to be used as an
active ingredient in (e.g., pharmaceutical) preparations for use on
the skin of the eyelids and on the ocular surface has been
found.
[0025] These compounds are suitable, for example, for use as agents
to reduce discomfort such as itch, a sense of dryness and
irritation, and pain.
[0026] These compounds have one or more of the following
properties: [0027] (i) a refreshing, soothing, and cooling action
on the surface of the skin and, in pathological states, act as an
anti-irritant, anti-pruritic, and/or anti-nociceptive agent [0028]
(ii) a minimal irritant action on the eye when the compound is
applied to facial skin near and on the ocular surface; [0029] (iii)
a rapid onset of action of less than 5 minutes, preferably less
than 1 minute; [0030] (iv) a duration of action that exceeds 1
hour, for example, when applied onto the upper eyelids at a
concentration of 0.2 to 2 mg/ml in a towelette; and [0031] (v) a
robust cool, soothing, and refreshing sensation when applied that
counteracts noxious or irritating stimuli on the ocular surface and
the mucous membranes of the eye.
[0032] These compounds may conveniently be referred to as
N-alkylcarbonyl- and N-alkyl-N-alkylcarbonyl-D-, L-, or DL-amino
acid esters or "NACE compounds".
[0033] In one embodiment, the compound is selected from compounds
of Formula (1):
##STR00001## [0034] wherein: [0035] R.sub.1 is hydrogen, or a
methyl group such that the carbon atom to which it is attached is
in the D-configuration, and [0036] when R.sub.1 is hydrogen,
R.sub.2 is isopropyl, and [0037] when R.sub.1 is a methyl group
such that the carbon atom to which it is attached is in the
D-configuration, R.sub.2 is a C.sub.1 to C.sub.3 alkyl group.
[0038] The menthyl group (i.e., the
5-methyl-2-(1-methylethyl)cyclohex-1-yl group) has the same
stereochemistry as found in (-)-menthol.
[0039] The .alpha.-carbon, between the --NH-- group and the
--C(.dbd.O)OR.sub.2 group, has the same stereochemistry as found in
D-alanine. This is also known as the R-configuration, according to
the Cahn-Ingold-Prelog nomenclature system. Except for glycine, all
.alpha.-amino acids have a chiral center at the .alpha.-carbon.
Although amino acids of the D-configuration are found in some
antibiotics and in cell membranes of microorganisms, the amino
acids of proteins are (almost) exclusively of the L (or S
configuration).
[0040] In one embodiment, R.sub.2 is independently methyl, ethyl,
or isopropyl
[0041] The isopropyl ester and the D-configuration have the effect
of increasing potency and duration of action, and of producing a
selective refreshing coolness near or on the ocular surface with
the absence of tissue irritation.
[0042] Examples of some preferred compounds are shown in Table 1,
ranked according to the duration of action on the ocular
surface:
TABLE-US-00001 TABLE 1 Preferred embodiments for applications. Code
Chemical Name Structure 1 D-Ala-OiPr (R)-2-[((1R,2S,5R)-2-
isopropyl-5-methyl- cyclohexanecarbonyl)-amino]- propionic acid
isopropyl ester ##STR00002## 2 Gly-OiPr (R)-2-[((1R,2S,5R)-2-
isopropyl-5-methyl- cyclohexanecarbonyl)-amino]- acetic acid
isopropyl ester ##STR00003## 3 D-Ala-OEt (R)-2-[((1R,2S,5R)-2-
isopropyl-5-methyl- cyclohexanecarbonyl)-amino]- propionic acid
ethyl ester ##STR00004## 4 D-Ala-OMe (R)-2-[((1R,2S,5R)-2-
isopropyl-5-methyl- cyclohexanecarbonyl)-amino]- propionic acid
methyl ester ##STR00005##
[0043] Preferred among these NACE compounds are "long-acting" NACE
compounds that, when applied to the skin or mucous membranes,
produce refreshing, soothing, and cooling sensations without skin
irritation, with minimal eye irritation, and with a duration of
action on skin that lasts more than about 1 hour when used at 0.20
to 2.0 mg/ml or less.
[0044] The long-acting NACE compounds are distinguished from other
N-alkylcarbonyl-amino acid esters (e.g., WS-5, see FIG. 1) and
N-alkyl substituted carboxamides (e.g., WS-3, WS-12, WS-23; see
FIG. 1) (WS-23 is N-2,3-trimethyl-2-isopropylbutanamide), which are
known to have cooling properties and the two (WS-3 and WS-23) that
are commercially used in comestibles, confectionery, and
toiletries.
[0045] As shown in Study 1, WS-3, WS-5, WS-12, WS-23 and WS-31,
have a short duration of action (less than 1 hour) on the philtrum
skin or slow onset (more than 5 minutes). Also, some of these
compounds do not achieve significant cooling but rather produce
skin sensations of tingling, burning, and irritation, effects
similar to those observed with (-)-menthol, a compound with
multimodal actions of sensory processes.
[0046] By contrast, the preferred long-acting NACE compounds
deliver a perfect cooling sensation, with rapid onset, long
duration of action, and minimal skin or eye irritation that has not
been previously recognized.
[0047] Furthermore, the potency, duration, and selectivity (absence
of irritation) of action are increased for the compounds of Formula
1, with R.sub.1.dbd.H, or C wherein the .alpha.-carbon is in the
D-configuration, and R.sub.2 is isopropyl.
[0048] Due to their prolonged activity, the compounds,
compositions, and articles may be used to inhibit the perception of
itch, pain, and discomfort from the skin and the mucous membranes
of the eyelids and ocular surface.
[0049] These compounds are without odor, smarting, or burning
sensations on the facial skin and in one embodiment, the compound
is carried on a towelette adapted for, or of sufficient
construction for, the delivery of a therapeutically effective
dose.
[0050] The specific structural features of the molecules that
confer the desired properties of increased potency and duration of
action, and the presence of refreshing cooling without irritation
were unexpected and surprising and not known in the prior art.
[0051] The term "effective amount," as used herein, pertains to
that amount of an active compound, or a material, composition or
dosage form comprising an active compound, which is effective for
producing some desired therapeutic effect, commensurate with a
reasonable benefit/risk ratio, when administered in accordance with
a desired treatment regimen.
[0052] Pharmacology and Mechanisms of Action of
N-Alkylcarbonyl-Amino Acid Esters
[0053] Noxious stimuli from the skin are thought to be transmitted
by unmyelinated C fibers and thinly myelinated A.delta. fibers,
together functionally called polymodal fibres. Noxious stimuli
produce sensory discomforts on the skin and in the mucous
membranes, discomforts which are ameliorated by cooling (vide
infra). Cooling of the facial skin and mucous membranes is detected
by a subset of primary sensory afferents that have receptors on
nerve endings. These sensory fibers exhibit a rhythmic, ongoing
discharge at neutral temperatures that increases in response to
skin temperature cooling (step reductions from 33 to 23.degree. C.)
and are suppressed by warming. The dynamic information is
propagated along axons in spike trains, at about 20 to 40
impulses/sec, to central neurons, leading to cooling sensations.
This type of sensation is mimicked by facial exposure to air or
water temperatures of 15 to 22.degree. C. The primary afferents
from facial skin terminate in the superficial layer of the caudal
trigeminal nucleus where they represent over 95% of the
thermoceptive input (see, e.g., Hutchinson et al., J.
Neurophysiol., 77:3252-3266, 1997).
[0054] The precise mechanisms underlying the benefits of refreshing
cooling on sensory discomfort are not clearly understood, although
such benefits are a common experience. Sensations can be
"confusing" when a chemical affects more than one sensory modality.
This is especially true for (-)-menthol (also known as L-menthol,
(1 R)-menthol, and (1 R,2S,5R)-menthol). (-)-Menthol is widely used
as a cooling agent but it has multimodal action on sensory
processes. For example, in the upper airways and oral cavity,
(-)-menthol can elicit cooling, irritation, tingling, minty flavor,
and bitter taste. Especially around the eyes, menthol is an
irritant and elicits sensations of burning, stinging, and pain.
[0055] The peripheral (-)-menthol coolness receptor is thought to
be a protein called TRP-M8. However, it has been found that the
potency of compounds that activate TRP-M8 is not correlated to
cooling actions (see, e.g., A. K. Vogt-Eisele, D. Bura, H. Hatt,
and E. T. Wei. N-Alkylcarboxamide Cooling Agents: Activities on
Skin and Cells with TRPM8 and TRPA1 Receptors. 3rd Annual Workshop
on the Study of Itch, Sep. 25 to 27, 2005 in Heidelberg, Germany.
Acta Dermato-Venereological 85: pg.468, 2005). Furthermore, TRP-M8
is activated by mustard oil, an agent that produces the pungent
sensations of wasabi. Thus, the compounds of the present invention
should not be viewed as solely acting via TRP-M8 receptors.
[0056] Although menthol preparations, such as confectionery, have
some alerting effects on the central nervous system, menthol
compositions cannot be applied to facial skin in effective
concentrations to arouse because it causes eye irritation
(stinging, smarting, tearing, and pain). Thus, identification of an
agent that does not irritate the eye surfaces, but which can be
applied to facial skin to refresh and to reduce skin irritation,
itch and pain would have utility.
[0057] Ideally, to treat skin and eye discomfort, a compound must
act for at least one hour and preferably longer, otherwise the
patient would have to repeatedly apply the drug to obtain relief.
For an anti-irritant, the ideal agent should have rapid onset of
action, soothing effects, and the ability to relieve discomfort for
an extended duration, for example, for several hours.
[0058] Non-Technical Description of Inventive Concept
[0059] It is believed that the long-acting NACE compounds described
herein activate the transmission of cool neurons so that the brain
perceives the ambient temperature at about 15 to 18.degree. C.
Activation of these neurons is like turning on a robust
air-conditioner within a hot environment. This sensory band in
normal individuals is felt as alerting, refreshing, and cool. This
is referred to herein as the "perfect cool." The presence of the
NACE compounds and the perfect cool, in pathological conditions,
gates the passage of noxious signals into the spinal cord and/or
brain. Hence, a soothing anti-nociceptive (anti-irritant,
anti-pruritic and antinociceptive) effect is achieved with
therapeutic benefit.
[0060] The inventor has identified molecules with potent and
prolonged activation of the perfect cool. These molecules are
qualitatively and quantitatively unlike (-)-menthol and WS-3 which
act for less than 20 minutes.
[0061] The long-acting NACE compounds are active at single doses
per eye of 1 to 50 .mu.g or at concentrations of 10 mg/mL or less
when applied topically to the facial skin including the eyelids.
The long-acting NACE compounds also have a rapid onset of action
(from about 0.5 to about 3 minutes). The onset and offset of action
of these compounds was first revealed by testing on the philtrum
skin of subjects and then subsequently by applying them onto the
skin near the eyes or on the closed eyelids with a towelette.
[0062] Bioassays of N-Alkylcarbonyl-Amino Acid Esters
[0063] Psychic events such as refreshment, soothing, cooling,
irritation, itch, and pain cannot be verbalized by animals (animals
cannot say "it feels cold", "ouch", or that "it itches"). Hence,
the sensory effects of chemicals in animals must be indirectly
inferred. Receptor assays, based on cells transfected with the
genes for proteins associated with thermosensation (e.g., TRP-M8,
TRP-A1, TRP-V1) may be used as a model of sensory processes. The
receptor assays yield quantitative data but give no information on
onset and offset of action, or on the quality of human sensations
evoked by the chemicals. Furthermore, potency as measured by the
median effective concentrations (EC.sub.60) in the receptor assays
may not be correlated to anti-nociceptive or cooling actions. Thus,
the best information on the pharmacological properties of chemicals
is derived from direct tests on humans.
[0064] Watson et al. (U.S. Pat. No. 4,178,459) tested the
properties of N-substituted p-menthane carboxamides. However, the
branched chain alkylesters such as the isopropyl analogs described
here in the Gly and D-Ala configuration of Formula 1 were never
synthesized by Watson et al. Bioactivity of the Watson et at
compounds were tested by putting filter paper (1.times.1 cm),
impregnated with a known amount of compound, onto the dorsal
surface of the tongue of the volunteer test subject. After 30
seconds, the subject was required to report presence or absence of
a cooling effect. These data were reported as "Threshold,82 g" and
refer to the threshold amount of the test substance that produces
cooling sensations upon application onto the tongue of a panel of
human volunteers. The average threshold of (-)-menthol for 6
subjects was 0.25 .mu.g, but there was a 100-fold variation in
individual sensitivity. The potencies of coolness signals detected
from the dorsal surface of the tongue are not correlated to skin
sensations of coolness may be confounded by gustatory, olfactory,
and other variables, as well as by dilution from saliva.
[0065] It has been found that, if the goal is to find a drug useful
for topical application, the refreshing cooling and sensory
properties of a long-acting NACE compound are best tested first by
suspending or dissolving a test substance in an ointment (usually
Aquaphor.RTM., which is 41% petrolatum, and the rest mineral oil,
ceresin and lanolin alcohol) and singly applying the ointment (40
to 70 mg) onto the skin surface using a plastic stick. A reliable
place for topical application is the skin above the upper lip
(above the vermilion border of the lips), on the philtrum, lateral
to the philtrum until the nasolabial folds, and on the lower
nostrils (subnasale). This part of the face is known to be densely
innervated with cold receptors, second only to the surfaces of the
eyeball and anogenitalia.
[0066] The intensity of the subjective skin sensation is rated as
0, 1, 2 or 3 with: 0 as no change; 1 as slight coolness, cold, or
tingling; 2 as clear-cut signal of coolness, cold, or tingling; and
3 as robust cooling or cold. The intervals for recording sensations
are 5 to 10 minutes, until two successive zeroes are obtained. The
results (shown in FIG. 1) are averaged values of 4 to 6 separate
trials in the same individual. The data are plotted using
SigmaPlot.RTM. (Systat Software, Point Richmond Calif.) and a
smoothing function with a negative exponential was used for
analysis and statistical fit of the results. Confirmatory trials of
cooling action of the long-acting NACE compounds were obtained in 2
to 4 individuals but not quantified for some because of the large
number of chemicals that were evaluated
[0067] The onset of drug action is taken as the time to reach 2
units of coolness intensity, and offset of drug action is the time
when coolness intensity drops below 2, after previously surpassing
2 units. The duration of cooling action is defined as the offset
time minus the onset time. An inactive compound is defined as one
that does not exceed 2 units of cooling for 5 minutes after
application. The quality of the sensation is noted, for example, as
pure refreshing coolness, or if the sensation is accompanied by
irritation (stinging or burning). The quality of the sensation is
not rated for intensity.
[0068] The ointment was also applied to the periorbital skin (upper
and lower eyelids and on skin adjacent to the lateral canthus) for
tests of irritancy near the eyes, and the subject is asked if
irritation is present or absent. The intensity of the eye sensation
is not rated.
[0069] A second method of testing was to take a towelette saturated
with a test solution of the cooling agent and to wipe the towelette
over the dosed eyelids. The presence or absence of cooling (or
irritanty, if applicable) sensations was then recorded at 10 minute
intervals until the cessation of coolness in two successive
intervals.
[0070] Qualitative Aspects of Cool and Cold Intensity
[0071] The long-acting NACE compounds described herein are useful
as a topical agent for the relief of skin discomfort, and mimic the
effects of running cold water on injured skin. The "nominal"
ambient skin surface temperature to mimic with a cooling agent is
in the range of 15 to 22.degree. C. The effect can also be
simulated by putting a towel wet with cold water onto the face. The
coolness of a wet towel will rapidly dissipate, an effect called
adaptation, even when the cooling stimulus is still there. On the
other hand, for a chemical agent applied to the facial skin, the
stimulus is more constantly present. The exact physiological
sensation to replicate with the inventive compounds is that of
refreshing, soothing coolness, with minimal or no sensations of
irritation or sting, and the absence of excessive cold.
[0072] The long durations of action of some preferred NACE
compounds on the philtrum skin and the ocular surfaces were
unexpected and surprising. Some of the compounds, especially the
isopropyl ester derivatives of glycine and D-alanine were found to
have cooling actions for three or more hours, an astonishing and
unexpected effect.
[0073] Uses of Long-Acting NACE Compounds on the Face and Other
Surfaces
[0074] In a preferred use, one or more long-acting NACE compounds
is topically applied to therapeutically relieve the irritation,
itch, and/or pain of inflamed surfaces. Other contemplated uses
include refreshment of the facial skin and to increase alertness
and vigilance.
[0075] Therapeutic uses for topical formulations of one or more
long-acting NACE compounds are contemplated in a towelette for
conjunctivitis, ocular surface irritation, pain from corneal
abrasions, and pain from eye surgery.
[0076] Delivery to Target and Utility of N-Alkylcarbonyl-Amino Acid
Esters
[0077] In practice, the long-acting NACE compound may also be
applied onto the skin using a towelette that is of a construction
sufficient or adapted to deliver the NACE compound to the skin.
Thus, the desired NACE compound is suspended, dissolved, and/or
dispersed so as to be in contact with the towelette. Suitable
towelettes include a pad that may be of woven or nonwoven material
usually in a unit dispenser. The wiping of the towelette or pad
across skin results in delivery to the skin of dermatologically
active ingredient(s), meaning that the skin is substantially
medicated. Other drugs, cosmeceuticals, herbal medicines,
traditional medicines, and active cosmetic ingredients suitable for
topical human use may also be incorporated into the towelette.
[0078] The ability of long-acting NACE compound to impart cooling
and refreshment in a towelette without sting, burn or irritation
(especially to the eyes), is an advance over current technology on
cooling agents. Known towelettes frequently contain SD Alcohol
(specially denatured alcohol; usually ethanol, isopropyl alcohol or
methanol), which is present as a solvent and/or a cooling agent.
Alcohol produces cooling when it abstracts heat from its environs
during evaporation. The drawback of using short-chain
carbon-alcohols in such formulations is that the alcohol dehydrates
tissues and causes irritation. When such a towelette is used near
the eyeball, the alcohol vapors irritate the eye surface.
Similarly, menthol, camphor, eucalyptol, and other ingredients
added to towelettes to produce fragrance and cooling also irritate
the skin and eyes.
[0079] In one embodiment, a long-acting NACE compound is carried by
a towelette, which, for example, when applied to the face, will be
especially valuable in counter-acting fatigue and to produce
alertness and increased vigilance; for example, to combat tiredness
from long car journeys or work in a hot environment.
[0080] Summary of Experimental Results from Bioassays
[0081] The principal findings from experiments performed on the
skin are summarized in FIG. 1 and Table 3. The beneficial effects
of the long-acting NACE compounds are the long duration of action
in the absence of significant eye irritation.
TABLE-US-00002 TABLE 2 Summary comparison of unique properties of
long-acting NACE compounds with other compounds. Cooling Cooling
"perfect" Acts for on on skin cooling Eye >1 hour at Chemical
Class tongue of face experience Irritancy 1 mg/ml Long-acting yes
yes yes no yes NACE non-NACE yes variable no yes no carboxamides
(-)-menthol yes yes no yes no SD alcohol no yes yes yes no
[0082] Chemical Synthesis of N-Alkylcarbonyl-Amino Acid Esters
[0083] Many substituted amino acid esters may be obtained from
commercial sources such Sigma-Aldrich Corp., St. Louis, Mo., USA.
For example, sarcosine ethyl ester, .beta.-alanine ethyl ester, R-
or S-amino butyrolactone, and L- or D-alanine methyl ester, are
listed in the 2003-2004 Aldrich Catalog. The precursor, D-alanine
ethyl ester is available from Indofine Chemicals, Co.,
Hillsborough, N.J. The precursor, D-alanine isopropyl ester is not
available from commercial sources and was custom synthesized
(Phoenix Pharmaceuticals, Burlingame, Calif.). The acid chloride is
reacted with the appropriate amino acid ester to form the NACE
compound.
[0084] As an example of synthetic procedure, D-Ala methyl ester
hydrochloride was obtained from Aldrich Chemical Co., 1.0 g was
dissolved in 28 mL diethyether and 1 mL double-distilled water and
cooled to 0.degree. C. A pinch of the catalyst diaminopyrimidine
was added. 1.62 mL of p-menthoyl chloride was then added dropwise,
followed by 2 mL of triethylamine. Clumps of white precipitates
appeared in the mixture, which was stirred overnight at room
temperature. The precipitate was dissolved with ethyl acetate,
washed with double-distilled water, and dried over sodium sulfate.
The organic phase was then evaporated under reduced pressure to
yield the final product (2 g), which crystallized at room
temperature. The expected molecular mass was then confirmed by mass
spectroscopy and the absorption spectrum by nuclear magnetic
resonance.
[0085] Bioassay Procedures
[0086] For bioassay on the skin, approximately 30 mg was stirred
and dissolved in 3 g of warm liquid Aquaphor.RTM. ointment to a
yield 5 to 10 mg/ml (0.5% to 1.0 wt/vol) ointment. After cooling,
40 to 70 mg of the solid ointment was placed on the tip of a
plastic stick and applied to the skin above the upper lip, on the
philtrum, and lateral to the philtrum, up to the nasolabial folds,
of test subjects and the onset and duration of cooling sensations
noted.
[0087] The intensity of the subjective skin sensation was rated as
0, 1, 2 or 3 with: 0 as no change; 1 as slight coolness, cold, or
tingling; 2 as clear signal of coolness, cold, or tingling; and 3
as robust cooling or cold. The intervals for recording sensations
were 5 to 10 minutes, until two successive zeroes were obtained.
The results (shown in FIG. 1) are averaged values of 4 to 6
separate trials in the same individual. The data are plotted using
SigmaPlot.RTM. (Systat Software, Point Richmond, Calif., USA) and a
smoothing function with a negative exponential was used for
analysis and statistical fit of the results.
[0088] The onset of drug action was taken as the time to reach 2
units of coolness intensity, and offset of drug action was the time
when coolness intensity drops below 2, after previously surpassing
2 units. The duration of cooling action was defined as the offset
time minus the onset time. An inactive compound is defined as one
that did not exceed 2 units of cooling after application. The
quality of the sensation was also noted: such as pure refreshing
coolness, or if the sensation was accompanied by irritation
(stinging or burning). The quality of the sensation was not rated
for intensity.
[0089] For tests of irritancy near the eyes in Study 3 and 4, the
ointment was applied to the periorbital skin (upper and lower
eyelids and on skin adjacent to the lateral canthus), and the
subject asked if irritation is present or absent. The intensity of
the eye sensation is not rated, but just noted as being present or
absent
[0090] For testing of cooling compounds delivered to the eyelids
with a towelette, the following procedures were used in the
experiments of Table 3 and in Study 5 and 6. Three ml of liquid
suspension or solution in distilled water was added to a 0.4 g
cotton rectangle (50 mm.times.60 mm) (CS-being, Daisan Cotton,
Japan) and individually sealed with a vaccuum apparatus
(Foodsaver.RTM., Jarden Corp.). Samples were stored in the freezer
or refrigerator and thawed to room temperature before use. Wiping
with the cotton pad delivers 40 to 45 .mu.l of liquid composition
to the eyelids (-20 to 22 .mu.l per eye). So, if the concentration
of the test substance was 1 mg/ml, the dose delivered to both eyes
is a total of .about.40 to 42 .mu.g, or .about.20 .mu.g per eye.
This method allows a reliable delivery of test substances because
the dissolved or suspended particles in solution are evenly
dispersed on the cotton pad in an excess volume of liquid. The
presence or absence of cooling sensations was noted as being
present or absent at 5 to 10 min intervals until no coolness was
noticeable in two successive test intervals. Only the duration of
cooling on the ocular surface was recorded, without an attempt to
quantify the intensity of the sensation.
[0091] Study 1
[0092] A number of compounds were synthesized and tested with the
results are shown in FIG. 1. For the results in FIG. 1, the test
compounds were singly applied to the skin above the upper lips at a
40 to 70 mg dose of a 1% wt/vol (10 mg/ml) ointment. Subsequently,
for the results shown in Table 3, the test dose on the philtrum was
reduced to a 0.5% wt/vol (5 mg/ml) ointment. The reason for
choosing a lower dose was to increase the number of trials per
individual and to have a reduced chance of substances accumulating
in the skin.
[0093] In FIG. 1, the duration of cooling effects of some known
agents, e.g., (-menthol, WS-3 and WS-5 are 0.3, 0.3, and 0.5 hour,
respectively, is relatively short compared to the NACE compounds,
specifically, D-Hsl, D-Ala-OMe and D-Ala-OEt analogs with 1.3, 1.9,
and 2.4 hours of cooling, respectively.
[0094] Long-acting NACE derivatives that have a refreshing cool,
without skin or eye irritancy (a "perfect cool") after facial skin
or periorbital applications, are identified by (*) in Table 3 and
Table 4. The exceptional long-acting properties of the isopropyl
analogs (see Table 1 and Table 3) are noted and not predictable
from the known physico-chemical properties of these molecules
(Table 4).
TABLE-US-00003 TABLE 3 Test results of substances applied to the
philtrum skin in an ointment vehicle and to the eylids with a
towelette. The test concentrations for the philtrum was 5 mg/ml in
Aquaphor .RTM. ointment and the concentrations for the eye wipes
was 1 mg/ml in 5%-95% v/v ethanol-distilled water. The duration of
cooling is recorded as (minutes). Formula (1) ##STR00006## Philtrum
Skin Eyelids/Ocular Compounds R.sub.1 R.sub.2 (minutes) Surface
(minutes) Gly Et Ester (WS-5) H Et 24 15 Gly iPr Ester (*) H iPr 27
300 Gly nPr Ester H nPr 42 54 Gly nBu Ester H nBu 38 35 D-Ala Me
Ester (*) Me Me 77 120 D-Ala Et Ester (*) Me Et 103 180 D-Ala iPr
Ester (*) Me iPr 34 360 D-Ala nPr Ester Me nPr 108 65 D-Ala nBu
Ester Me nBu 80 40 L-Ala Et Ester Me Et 34 0 D-NMe Ala Ester Me Me
0 0 (*) denotes compounds that fulfill the criteria of being a
long-acting NACE compound for towelette applications (i.e., >1
hour duration of action).
TABLE-US-00004 TABLE 4 Some properties of tested compounds. The
tongue threshold values are from Watson US 04178459. The pure (*)
compounds were never synthesized by Watson et al. Molecular
Threshold Compound Weight tongue (.mu.g) Log P Gly Me Ester (WS-31)
255.4 0.6 2.4 Gly Et Ester (WS-5) 269.4 0.2 2.9 Gly n-Pr Ester
283.4 0.3 3.4 Gly i-Pr Ester (*) 283.4 -- 3.3 Gly n-Bu Ester 297.4
-- 4.0 Sar Et Ester 283.4 0.8 2.9 L-Ala Et Ester 283.4 0.4 3.1
L-Ala Me Ester 269.4 0.6 2.8 D-Ala Me Ester (*) 269.4 -- 2.8 D-Ala
Et Ester (*) 283.4 -- 3.1 D-Ala i-Pr Ester (*) 297.4 -- 3.7 D-Ala
n-Pr Ester 297.4 -- 3.8 D-Ala n-Bu Ester 311.4 -- 4.4 N--Me-D-Ala
Et Ester 297.4 -- 3.2 .beta.-Ala Et Ester 283.4 1.5 3.1 D-Hsl 267.4
-- 2.5 L-Hsl 267.4 -- 2.5 racemic Hsl 267.4 -- 2.5 WS-3 211.3 0.2
3.7 WS-10 225.4 0.4 4.1 WS-34 239.4 0.7 4.6 WS-14 239.4 0.4 4.5
WS-11 255.4 0.3 2.9 WS-12 289.4 0.2 5.3 L-Ser Et Ester 285.4 -- 1.8
L-Val Me Ester 297.4 -- 4.2 D-Val Me Ester 297.4 -- 4.2 Glu(OMe) Me
Ester 341.4 -- 2.2 L-Leu Me Ester 311.5 -- 4.3 L-Pro Me Ester 295.4
-- 3.3 L-Lys(Z) t-Bu Ester 502.7 -- 5.9 L-Tyr Me Ester 364.2 -- 3.7
(*) denotes compounds that fulfill the criteria of being a
long-acting NACE compound for towelette applications (i.e., >1
hour duration of action). (Gly = glycine; Sar = sarcosine; Ala =
alanine; Hsl = homoserine lactone (also known as
.alpha.-amino-butyro-.gamma.-lactone))
[0095] Study 2
[0096] 2-Isopropyl-5-methyl-cyclohexanecarbonyl D-alanine methyl
ester was dissolved in warm 10% propylene-glycoV90% distilled water
solution to give a concentration of either 0.1 or 0.5% wt/vol (1 or
5 mg/mL). Six to seven milliliters of these solutions were then
applied with a pipette onto a paper napkin (Luncheon Napkins,
Kirkland Signature brand from Costco, Inc.) The napkin was 1-ply
with a 30.4.times.29.5 cm dimension. Each napkin was then
hermetically sealed in a plastic envelope (Foodsaver by Tilia). On
two separate occasions involving golfing trips to Los Angeles,
Calif., USA, where air temperatures exceeded 332.degree. C.
(90.degree. F.), these towelettes were used to wipe the face.
Pleasant cooling sensations were obtained that lasted for about 10
minute for the 0.1% concentration towelette and about 60 minutes
for the 0.5% towelette. No eye irritation was observed with either
concentration.
[0097] Study 3
[0098] A 1% preparation of 2-isopropyl-5-methyl-cyclohexanecarbonyl
D-alanine methyl ester in Aquaphor.RTM. ointment was applied
bilaterally to the periorbital area of four individuals. Onset of
coolness on the skin was noted with 1 minutes and lasting for an
average of 30 minutes. No irritation of the eye surfaces was noted.
Surprisingly, all four individuals noted an alerting effect and an
ability to focus and see more clearly. This alerting effect lasted
for about one hour. This experiment was then repeated three days
later in the evening with the same individuals whose occupations
required daylong activities before a computer screen. Again,
application of the ointment about the periorbital area was reported
to relieve fatigue, enhance visual acuity, and to increase
attention span and focus. Sensations of refreshment and improved
mood were also noted. By contrast, tests with other carboxamides,
WS-3, WS-23, WS-11, and WS-14, under similar conditions, showed
that they produced significant skin and eye irritation and did not
enhance skin coolness or provide satisfactory refreshment
[0099] Study 4
[0100] Three high-powered business executives who regularly spent
long hours at the negotiating tables or at meetings felt "burnt
out" by their professional activities and frequently felt tired and
sleepy-eyed in the social arena. They volunteered to try eye wipes
containing 1.0 mg/ml of
(R)-2-[((1R,2S,5R)-2-isopropyl-5-methyl-cyclohexanecarbonyl)-amino]-propi-
onic acid isopropyl ester (D-Ala-OiPr, No. 1, in table 1) to see if
the eye wipes will refresh and awaken their interest during
meetings. All three said when coffee was no longer able to keep
them awake, they went to the bathroom and applied the eye wipe and
the sense of sleepiness and fatigue was reduced for the next
several hours. They became alert and vigilant and more pro-active
in their social milieu. Similar results were obtained with the
Gly-OiPr, D-Ala-OMe, and D-Ala-OEt analogs. It was generally opined
that the latter two analogs had a faster onset and more intense
awakening effect.
[0101] Study 5
[0102] A laboratory scientist suffered from seasonal allergic
conjunctivitis. This condition was severely aggravated when he
started doing experiments with laboratory animals (rats and mice)
and he became sensitized to the associated allergens. The
conjunctivitis was not relieved by oral or topical eye drop
antihistamines and the subject was reluctant to consider the use of
anti-inflammatory steroid ointments. Upon examination, his eyes
were blood-shot and watery and he kept rubbing his eyelids with his
fingers even though he knew this action may further aggravate the
itch and discomfort. He volunteered to try eye wipes containing 1.0
mg/ml of (R)-2-[((1
R,2S,5R)-2-isopropyl-5-methyl-cyclohexanecarbonyl)-amino]-acetic
isopropyl ester (Gly-OiPr, No. 2, in table 1). The relief of itch
and discomfort was obtained within 5 minutes and lasted for at
least four hours. He used the wipes on an "as-needed basis" for
three days and was surprised to see that his over-all itchiness and
redness were reduced significantly.
[0103] Study 6
[0104] A 60-year old woman suffered from "dry eyes" or
keratoconjunctivitis sicca which was managed by artificial tears
and eye drops containing lubricants. She then underwent cataract
surgery and started to complain of persistent severe periorbital
pain. She will wake up at night in severe discomfort and not be
able to sleep. This condition persisted for six months and her
quality of life deteriorated and she began to lose weight.
Consultation with the ophthalmologist who performed the surgery was
not helpful, as he could not detect any physical signs of injury to
the eye. Pain in the "quiet eye" (see Brazis et al. Clinical
review: the differential diagnosis of pain the quiet eye. The
Neurologist 8: 82-100, 2002) is a well-known syndrome with many
causes. She volunteered to try eye wipes containing 1.0 mg/ml of
(R)-2-[((1R,2S,5R)-2-isopropyl-5-methyl-cyclohexanecarbonyl)-amino]-aceti-
c isopropyl ester (Gly-OiPr, No. 2, in table 1) and she obtained
immediate relief on three occasions and was able to go to sleep.
Subsequently, she went to another ophthalmogist who specialized in
corneal diseases. He diagnosed her condition as infective
blepharitis and prescribed a topical antibiotic and a topical
anti-inflammatory steroid. These medications have now restored her
health.
[0105] The foregoing has described the principles, preferred
embodiments, and modes of operation of the present invention.
However, the invention should not be construed as limited to the
particular embodiments discussed. Instead, the above-described
embodiments should be regarded as illustrative rather than
restrictive, and it should be appreciated that variations may be
made in those embodiments by workers skilled in the art without
departing from the scope of the present invention.
* * * * *