Hair loss abstract
A method for inhibiting hair loss and/or promoting hair growth
in chemotherapy and/or radiation therapy patients wherein the (R)-enantiomer
of 4-[[(cyanoimino)-[(1,2,2-trimethylpropyl)amino]methyl]amino]benzonitrile
is administered prior to, simultaneous with and/or after chemotherapy
and/or radiation treatment.
Hair loss claims
What is claimed is:
1. A method for promoting hair growth in a patient having chemotherapy-induced
hair loss or radiation-induced hair loss, which comprises administering
to a human or other mammal a therapeutically effective amount of
the (R)-enantiomer of 4-[[(cyanoimino)[(1,2,2-trimethylpropyl)amino]methyl]amino]benzonitrile.
2. The method as defined in claim 1 wherein the (R)-enantiomer
is administered prior to, or subsequent to chemotherapy or radiation
therapy.
3. The method as defined in claim 1 wherein the (R)-enantiomer
is administered prior to chemotherapy or radiation therapy.
4. The method as defined in claim 1 wherein the (R)-enantiomer
is administered subsequent to chemotherapy or radiation therapy.
5. The method as defined in claim 1 wherein the (R)-enantiomer
is administered topically.
6. The method as defined in claim 1 wherein the (R)-enantiomer
is administered as a cream formulation, lotion formulation, liquid
formulation or ointment formulation.
7. The method as defined in claim 1 wherein the (R)-enantiomer
is administered systemically.
8. The method as defined in claim 1 for promoting hair growth in
a patient having chemotherapy-induced hair loss.
9. The method as defined in claim 1 for promoting hair growth in
a patient having radiation-induced hair loss.
10. The method according to claim 1 wherein the (R)-enantiomer
is administered in conjunction with a chemotherapeutic agent.
11. The method according to claim 1 wherein the (R)-enantiomer
is administered in conjunction with a chemotherapeutic agent which
is an antineoplastic agent selected from the group consisting of
an anthracycline drug, a vinca drug, a mitomycin, a bleomycin, a
cytotoxic nucleoside, a taxane, an epothilone, discodermolide, a
pteridine drug, a diynene, an aromatase inhibitor and a podophyllotoxin.
12. The method according to claim 1 wherein the (R)-enantiomer
is administered in conjunction with a chemotherapeutic agent which
is an antineoplastic agent selected from the group consisting of
paclitaxel, docetaxel, 7-O-methylthiomethyl-paclitaxel, 3'-tert-butyl-3'-N-tert-butyloxycarbonyl-4-deacetyl-3'-dephenyl-3'-N-deben
zoyl-4-O-methoxycarbonyl-paclitaxel, C-4 methyl carbonate paclitaxel,
epothilone A, epothilone B, epothilone C, epothilone D, desoxyepothilone
A, desoxyepothilone B, [1S-[1R*,3R*(E),7R*,10S*,11R*,12R*, 16S*]]-7,11-dihydroxy-8,8,10,12,16-pentamethyl-3-[1-methyl-2-(2-methyl-4-t
hiazolyl)ethenyl]-4-aza-17-oxabicyclo[14.1.0]heptadecase-5,9-dione,
[1S-[1R*,3R*(E),7R*,10S*,11R*,12R*,16S*]]-3-[2-[2-(aminomethyl)-4-thiazoly
l]-1-methylethenyl]-7,11-dihydroxy-8,8,10,12,16-pentamethyl-4,17-dioxabicyc
lo[14.1.0]heptadecane-5,9-dione, doxorubicin, carminomycin, daunorubicin,
aminopterin, methotrexate, methopterin, dichloro-methotrexate, mitomycin
C, porfiromycin, 5-fluorouracil, 6-mercaptopurine, gemcitabine,
cytosine arabinoside, podophyllotoxin, etoposide, etoposide phosphate,
teniposide, melphalan, vinblastine, vincristine, leurosidine, vindesine,
leurosine, estramustine, cisplatin, carboplatin, cyclophosphamide,
bleomycin, tamoxifen, ifosamide, hexamethyl melamine, thiotepa,
cytarabin, idatrexate, trimetrexate, dacarbazine, L-asparaginase,
camptothecin, CPT-11, topotecan, ara-C, bicalutamide, flutamide,
leuprolide, a pyridobenzoindole, an interferon and an interleukin.
13. The method as defined in claim 1 wherein the (R)-enantiomer
is administered in the form of a topical formulation comprising
ethanol, propylene glycol and water.
14. The method as defined in claim 13 wherein the ethanol/propylene
glycol/water are in a 60/30/10 proportion.
15. The method as defined in claim 1 wherein the (R)-enantiomer
is administered in an amount from about 0.01 to about 15% by weight
of said (R)-enantiomer.
16. The method as defined in claim 1 wherein the (R)-enantiomer
is administered in the form of ethanol/propylene glycol/water, 60/30/10,
is an amount to provide a 2% solution of the (R)-enantiomer.
17. The method as defined in claim 1 wherein the (R)-enantiomer
is administered in combination with one or more other hair growth
promoting agents.
18. The method as defined in claim 17 wherein said other hair growth
promoting agent is another potassium channel opener, a 5-.alpha.-reductase
inhibitor, an androgen blocker, betamethasone dipropionate, a corticosteroid,
scopolamine and/or cyproterone acetate.
19. The method as defined in claim 18 wherein the other potassium
channel opener is minoxidil, diazoxide, cromakalim and/or pinacidil;
the 5-.alpha.-reductase inhibitor is finasteride, terazosin HCl,
and/or doxaosin mesylate; the androgen blocker is 4-(5-methoxyheptyl)-hexahydro-2(1H)-pentalenone;
and the corticosteroid is hydrocortisone.
20. The method as defined in claim 19 wherein said other hair growth
promoting agent is a 5-.alpha.-reductase inhibitor.
21. The method as defined in claim 20 wherein the 5-.alpha.-reductase
inhibitor is finasteride.
Hair loss description
FIELD OF THE INVENTION
The present invention relates to a method for inhibiting hair loss
and/or promoting hair growth in chemotherapy patients employing
the (R)-enantiomer of 4-[[(cyanoimino)[(1,2,2-trimethylpropyl)amino]methyl]amino]benzonitrile
or pharmaceutical compositions containing same.
BACKGROUND OF THE INVENTION
Potassium channel openers such as minoxidil (Upjohn), pinacidil
(Lilly) and diazoxide (Shiseido and Schering-Plough) are known for
their hair growth stimulating activity. Thus, U.S. Pat. Nos. 4,596,812
and 4,139,619 disclose use of minoxidil in the treatment of male
pattern baldness, alopecia areata and balding in females. U.S. Pat.
No. 4,057,636 discloses pinacidil. DE 3,827,467A discloses combinations
of minoxidil and hydrocortisone or retinoids.
U.S. Pat. No. 5,011,837 to Atwal et al discloses aryl cyanoguanidines
which possess potassium channel activating activity and are useful
therapy for hypertension and other cardiovascular disorders, for
various central nervous system disorders, kidney and urinary problems
as well as for the promotion of hair growth, for example in the
treatment of male pattern baldness (alopecia). These aryl cyanoguanidines
have the structure ##STR1##
and its possible tautomers ##STR2##
and ##STR3##
including pharmaceutically acceptable salts, wherein
R.sub.1 is alkyl, alkenyl, alkynyl, haloalkyl, cycloalkyl, aryl,
arylalkyl or cycloalkylalkyl;
R.sub.2 is ##STR4##
R.sub.3 and R.sub.4 are each independently selected form -R.sub.2,
hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, halo, alkoxy, --NHalkyl,
--N-(alkyl).sub.2, --S-alkyl, --O-aryl-alkyl, --S-arylalkyl or --S-aryl,
--O-aryl, --NHaryl-alkyl, or R.sub.2 and R.sub.3 taken together
are a group which form a ring with the two carbon atoms to which
they are attached, which group is selected from ##STR5##
wherein
m=1 or 2,
n=3-5,
p=2-4,
X is 0, NR.sub.5, CH.sub.2 ; and
R.sub.5 is hydrogen or R.sub.1.
Example 1 of U.S. Pat. No. 5,011,837 discloses the preparation
of 4-[[(cyanoimino)-[(1,2,2-trimethylpropyl)amino]benzonitrile ##STR6##
in the form of its racemic mixture.
U.S. Pat. No. 6,013,668 discloses a method for promoting hair growth
in humans employing the (R)-enantiomer of 4-[[(cyanoimino)[(1,2,2-trimethylpropyl)-amino]methyl]amino]benzonitrile.
PCT Application WO 92/02225 discloses a combination of a potassium
channel opener and a 5-.alpha.-reductase inhibitor for promoting
hair growth.
PCT Application WO 92/09259A discloses use of an androgen blocker
and a potassium channel activator for stimulation of hair growth.
PCT Application WO 96/29988 discloses a topical formulation containing
minoxide or minoxidil in combination with a testosterone 5-.alpha.
reductase inhibitor.
PCT Application WO 94/18936 discloses a method for promoting hair
growth employing a vasodilator such as minoxidil in combination
with estradiol and/or a 5-.alpha.-reductase inhibitor.
The use of minoxidil in cancer patients to decrease the duration
of baldness caused by chemotherapy is disclosed by Duvic, M. et
al, "A randomized trial of minoxidil in chemotherapy-induced
alopecia", J. Am. Acad Dermalol 1996; 35:74-8. Duvic et al
disclose that in patients treated with fluorouracil, doxorubicin
and cyclophosphamide a 2% topical solution of minoxdil administered
during chemotherapy and 4 weeks thereafter, did not prevent alopecia
but did decrease period of baldness.
Rodriguez, R. et al "Minoxidil (Mx) as a prophylaxis of doxorubicin-induced
alopecia", Annals of Oncology 5:769-770, 1994 discloses that
a 2% topical solution of minoxidil was not effective in preventing
doxorubicin-induced alopecia.
Hussein, A. M., "Protection Against Cytosine Arabinoside-Induced
Alopecia By Minoxidil In A Rat Animal Model", Int. J. Dermatol.
Vol. 34(7); 470-3, 1995 discloses that minoxidil, when injected
locally, offered good local prevention against 1-B-D-arabinofurano-sylcytosine
but not cyclophosphamide-induced alopecia.
DESCRIPTION OF THE INVENTION
In accordance with the present invention, a method is provided
for preventing or inhibiting chemotherapy-induced or radiation therapy-induced
hair loss wherein a therapeutically effective amount of the (R)-enantiomer
of 4-[[(cyanoimino)[(1,2,2-trimethylpropyl)-amino]methyl]amino]benzonitrile,
(hereinafter "the (R)-enantiomer") is administered to
a human or other mammal.
In addition, in accordance with the present invention, a method
is provided for promoting hair growth in a patient undergoing chemotherapy
or radiation and/or having chemotherapy-induced hair loss or radiation-induced
hair loss, wherein a therapeutically effective amount of the (R)-enantiomer
is administered to the patient.
In carrying out the above methods, the (R)-enantiomer will be administered
to the patient prior to and/or simultaneously with and/or subsequent
to chemotherapy and/or radiation therapy.
The above (R)-enantiomer of the invention has the structure I ##STR7##
The (R)-enantiomer will preferably be in substantially pure form,
that is, will be at least 99% pure (R)-enantiomer and will at most
contain 1% (S)-enantiomer.
The method of the present invention also includes the use of pharmaceutical
compositions containing the (R)-enantiomer and a pharmaceutically
acceptable carrier therefor.
The (R)-enantiomer may be prepared as described in U.S. Pat. No.
6,013,668 which is incorporated herein by reference.
The (R)-enantiomer may be administered by itself or may be administered
prior to, simultaneous with or after the antineoplastic agent used
in chemotherapy, or prior to simultaneously with or after radiation
therapy. In a preferred embodiment of the present invention, the
(R)-enantiomer is administered prior to the antineoplastic agent
or radiation therapy.
As used herein, the term "simultaneous" means that the
antineoplastic agent or radiation therapy and the (R)-enantiomer
are administered within 24 hours, preferably 12 hours, more preferably
6 hours, and most preferably 3 hours, of each other.
The chemotherapeutic agent which may be employed with the (R)-enantiomer
may include any of the antineoplastic agents listed in the Physician's
Desk Reference.
As used herein, the phrase "radiation therapy" includes,
but is not limited to, x-rays or gamma rays which are delivered
from either an externally applied source such as a beam or by implantation
of small radioactive sources.
As used herein, the phrase "antineoplastic agent" refers
to compounds which prevent cancer cells from multiplying. In general,
the antineoplastic agents of this invention prevent cancer cells
from multiplying by: (1) interfering with the cell's ability to
replicate DNA, or (2) inducing apoptosis in the cancerous cells.
Examples of antineoplastic agents which are suitable for use in
the methods of this invention include, but are not limited to, microtuble-stabilizing
agents such as the taxanes, for example, paclitaxel (also known
as Taxol.RTM.), docetaxel (also known as Taxotere.RTM.), 7-O-methylthio-methylpaclitaxel
(disclosed in U.S. Pat. No. 5,646,176), 3'-tert-butyl-3'-N-tert-butyloxycarbonyl-4-deacetyl-3'-dephenyl-3'-N-deben
zoyl-4-O-methoxycarbonyl-paclitaxel (disclosed in U.S. Ser. No.
60/179,965 filed on Feb. 3, 2000, and example 17 herein), C-4 methyl
carbonate paclitaxel (disclosed in WO 94/14787), the epothilone,
such as epothilone A, epothilone B, epothilone C, epothilone D,
desoxyepothilone A, desoxyepothilone B, [1S-[1R*,3R*(E),7R*,10S*,11R*,12R*,16S*]]-7,11-dihydroxy-8,8,10,12,16-pent
amethyl-3-[1-methyl-2-(2-methyl-4-thiazolyl)ethenyl]-4-aza-17-oxabicyclo[14
.1.0]hepta-decane-5,9-dione (disclosed in WO 99/02514), [1S-[1R*,3R*(E),7R*,10S*,11R*,12R*,16S*]]-3-[2-[2-(aminomethyl)-4-thiazoly
l]-1-methylethenyl]-7,11-di-hydroxy-8,8,10,12,16-pentamethyl-4,17-dioxabi-c
yclo[14.1.0]-heptadecane-5,9-dione (disclosed in U.S. Ser. No. 09/506,481
filed on Feb. 17, 2000, and examples 7 and 8 herein), and derivatives
thereof; microtuble-disruptor agents; alkylating agents; anti-metabolites;
epidophyllotoxin; an antineoplastic enzyme; a topoisomerase inhibitor;
procarbazine; mitoxantrone; platinum coordination complexes; biological
response modifiers; growth inhibitors; hormonal/antihormonal therapeutic
agents; and haematopoietic growth factors.
Other classes of antineoplastic agents suitable for use in the
method of the present invention include, but are not limited to,
the anthracycline family of drugs, the vinca drugs, the mitomycins,
the bleomycins, the cytotoxic nucleosides, discodermolide, the pteridine
family of drugs, diynenes, aromatase inhibitors, and the podophyllotoxins.
Particularly useful members of those classes not previously mentioned
include, for example, doxorubicin, carminomycin, daunorubicin, aminopterin,
methotrexate, methopterin, dichloro-methotrexate, mitomycin C, porfiromycin,
5-fluorouracil, 6-mercaptopurine, gemcitabine, cytosine arabinoside,
podophyllotoxin or podophyllotoxin derivatives such as etoposide,
etoposide phosphate or teniposide, melphalan, vinblastine, vincristine,
leurosidine, vindesine, leurosine, and the like. Other useful antineoplastic
agents include estramustine, cisplatin, carboplatin, cyclophosphamide,
bleomycin, tamoxifen, ifosfamide, melphalan, hexamethyl melamine,
thiotepa, cytarabin, idatrexate, trimetrexate, dacarbazine, L-asparaginase,
camptothecin, CPT-11, topotecan, ara-C, bicalutamide, flutamide,
leuprolide, pyridobenzoindole derivatives, interferons, and interleukins.
In carrying out the method of the invention, the (R)-enantiomer
may be formulation with other hair growth promoting compounds such
as the potassium channel openers minoxidil (Upjohn) and/or diazoxide
(Shiseido and Schering-Plough), as well as cromakalim and pinacidil;
a 5-.alpha.-reductase inhibitor such as finasteride (Merck's Proscar.RTM.),
terazosin HCl (Abbott's Hytrin.RTM.), or doxaosin mesylate (Pfizer's
Cardura.RTM.); and/or an androgen blocker such as 4-(5-methoxyheptyl)-hexahydro-2(1H)-pentalenone
as disclosed in PCT Application WO 92/09259A, vasoconstrictors such
as betamethasone dipropionate, corticosteroids such as hydrocortisone,
and scopolamine, and cyproterone acetate.
The (R)-enantiomer may be administered via topical, oral, parenteral
or rectal routes as described in U.S. Pat. No. 5,011,837 (incorporated
herein by reference), with topical being preferred, to humans or
other mammals such as dogs and cats prior to, simultaneous with
and/or subsequent to chemotherapy and/or radiation therapy. Thus,
the (R)-enantiomer in suitable topical formulations is applied to
the skin region where hair growth is desired and/or where hair loss
is to be inhibited.
Typical topical formulations for use herein will include conventional
ointments, creams, lotions, waxes, gels, pastes, jellies, sprays,
aerosols and the like in aqueous or non-aqueous formulations. Examples
of suitable topical formulations are disclosed in U.S. Pat. Nos.
4,139,619 and 4,596,812 which are incorporated herein by reference.
The (R)-enantiomer will be used in an effective amount, that is,
in an amount sufficient to inhibit hair loss during chemotherapy
and/or radiation therapy and/or promote hair growth during and/or
subsequent to chemotherapy and/or radiation therapy, such that hair
growth is increased or produced. A typical topical composition will
include from about 0.01 to about 15% by weight, preferably from
about 0.1 to about 10% by weight of the composition.
The topical formulations containing the (R)-enantiomer of the invention
can be applied to the area to be treated such as the scalp in humans,
by spraying, dabbing or swabbing to deliver the enantiomer to the
region of the hair follicle. The formulations will be applied to
the area of treatment on a routine basis prior to, during and subsequent
to chemotherapy and/or radiation therapy, at least once daily, and
preferably two or more times daily.
The accompanying Figure is a graph showing the effect of a once
daily application of each of the (R)- and (S)-enantiomers described
herein on hair growth in male C3H mice.
The following Example describes the preparation of the (R)-enantiomer
and the (S)-enantiomer.
EXAMPLE 1
(R)-4-[[(Cyanoimino)[(1,2,2-trimethylpropyl)amino]-methyl]amino]benzonitril
e ##STR8## A. (R)-1,2,2-Trimethylpropyl amine ##STR9##
The title compound was prepared according to the procedure described
by Manley and Quast (J. Med. Chem. 1992, 35, 2327-2340) with some
modification. A mixture of pinacolone (29 g, 290 mmol), (R)-.alpha.-methylbenzyl
amine (17.6 g, 145 mmol) and p-toluenesulfonic acid monohydrate
(300 mg) in toluene (150 mL) was refluxed using a Dean-Stark trap
(to remove water from the reaction mixture) for 3 days. The solvent
was evaporated and the residue was distilled at ca. 120-2.degree.
C. (9 mm) to give 21 g (71% yield) of ##STR10##
as a colorless oil. This material was dissolved in anhydrous THF
(210 mL) and treated at 0-2.degree. C. with borane-THF complex (1M,
206 mL, 206 mmol). The mixture was allowed to come to room temperature,
stirred for 5 h and concentrated in vacuo. To the resulting oily
residue was carefully added ethanol (300 mL), and the mixture was
refluxed for 1 h and concentrated again in vacuo. The residue was
chromatographed over basic alumina (activity grade 1/hexane) giving
colorless oil. Proton NMR and HPLC (YMC Cl8 S3 4.6X50 mm column/water-MeOH--H.sub.3
PO.sub.4 90:10:0.2 to 10:90:0.2 gradient) indicated that this material
was contaminated with ca. 10% of the (S,R)-diastereomer. Therefore,
this mixture was resubjected to flash chromatography (silica gel/hexane-EtoAc-triethylamine
95:5:0.1) to afford ##STR11##
(11.45 g, 55.8 mmol, 54% yield). The above compound (11.45 g) and
10% palladium on carbon (1.5 g) were taken in EtOH (230 mL) and
stirred under hydrogen for 12 hours. The mixture was filtered and
the filtrate (ca. 230 mL) containing the title product was used
as such for the next step as a ca. 0.24 M solution in ethanol (assumed
100% yield). B. N-Cyano-N'-(4-cyanophenyl)thiourea, monosodium salt
##STR12##
The title compound was prepared according to Example 1 Part A of
U.S. Pat. No. 5,011,837. C. (R)-4-[[(Cyanoimino)[(1,2,2-trimethyl-propyl)amino]methyl]amino]benzonitri
le ##STR13##
To a solution of Part B compound (6.0 g, 26.8 mmol) in DMF (150
mL) was sequentially added the solution of Part A compound (ca.
0.24 M in EtOH, 112 mL, 26.8 mmol) and 1-(3-dimethylamino-propyl)-3-ethylcarbodiimide
hydrochloride (WSC) (6.0 g, 31.3 mmol). The mixture was stirred
at room temperature for 3 hours, diluted with ethyl acetate and
sequentially washed with 1N HCl, water and brine. The organic layer
was dried over magnesium sulfate, concentrated and the crude product
was purified by flash chromatography on silica gel (hexanes-ethyl
acetate-triethylamine 75:25:0.2) to afford a colorless foam. This
material was recrystallized from isopropanol to give the title compound
as a white solid (4.15 g, 57.6%), mp 159-60.degree. C.; [.alpha.].sub.D
-180.degree. C.=1, MeOH; enantiomeric purity determined by chiral
HPLC=99% (ChiralPak AD column/hexane-isopropanol-triethylamine 80:20:0.2);
MS: 270 (M+H).sup.+ ; .sup.1 H NMR (CDCl.sub.3) .delta. 8.65 (br
s, 1H), 7.69 (d, 2H, J=8.79 Hz), 7.37 (d, 2H, J=8.79 Hz), 4.93 (br
d, 1H), 3.83 (m, 1H), 1.10 (d, 1H, J=6.45 Hz), 0.90 (s, 9H).
Elemental analysis: calculated for C.sub.15 H.sub.19 N.sub.5 :
C, 66.89; H, 7.11; N, 26.00
Found: C, 66.71; H, 7.14; N, 25.98.
EXAMPLE 2
(S)-4-[[(Cyanoimino)[(1,2,2-trimethylpropyl)amino]-methyl]amino]benzonitril
e ##STR14##
The title compound was prepared from Part B compound of Example
1 and (S)-1,2,2-trimethylpropyl amine (prepared according to Manley
and Quast, J. Med. Chem., 1992, 35, 2327-2340) by the same procedure
as described in Example 1, Part C. The product was obtained as a
colorless solid, mp 158-59.degree. C.; [a].sub.D +189.degree. C.=1,
MeOH; enantiomeric purity determined by chiral HPLC=99.4% (ChiralPak
AD column/hexane-isopropanol-triethylamine 80:20:0.2); MS: 270 (M+H).sup.+
; .sup.1 H NMR (CDCl.sub.3) .delta. 8.43 (br s, 1H), 7.69 (d, 2H,
J=8.79 Hz), 7.37 (d, 2H, J=8.79 Hz), 4.93 (br d, 1H), 3.83 (m, 1H),
1.10 (d, 1H, J=6.45 Hz), 0.90 (s, 9H).
EXAMPLE 3
Comparison of Example 1-(R)-Enantiomer and Example 2-(S)-Enantiomer
Re Hair Growth in an Animal Model
The objective of the following described experiment was to compare
and evaluate the in vivo effect of the Example 1-(R)-enantiomer
and the Example 2-(S)-enantiomer on hair growth in an animal model.
The two enantiomers were compared topically for hair growth in C3H
mice.
Animal Model
The C3H mouse is a useful model for studying hair growth. Its usefulness
rests with the fact that skin pigmentation of this animal is provided
by the melanocytes of the hair follicle and not the epidermis. In
the telogen or the resting phase of the hair follicle, the skin
is pink. In the earliest phase of anagen or the growth phase, there
is sudden graying of the skin and as the anagen phase progresses
the skin becomes darker in color. In this study, visual observation
was used as an in vivo assay of anagen induction. Furthermore as
anagen develops, the skin thickness increases from a thin telogen
skin to a measurably thickened anagen skin. Thus, recording the
skin color and microscopic thickness of skin from these mice offers
a sensitive, quantifiable and convenient method of assessing the
phases of hair growth.
Groups of 20, six to seven week old male C3H mice with hair follicles
in the resting phase of hair growth were used. At this stage in
their life, the hair follicles remain in the telogen phase for up
to 30 days or longer. This provides an adequate window of time to
screen drugs. Compounds that improve hair growth stimulate the hair
follicles from the telogen to the anagen phase. This stimulation
is manifested by the shortening of the telogen phase of the hair
follicle cycle.
Animals were anesthetized with ketamine/rompun (100 mg/Kg and 12
mg/Kg) IP and the hair over a defined dorsal area were closely clipped.
Animals with pink skin were treated topically 1.times. daily, 5
days per week with 50 microliters of a 2% solution of Example 1-(R)-enantiomer
and a 2% solution of Example 1-(S)-enantiomer or vehicle by itself,
applied to the dorsal area. The vehicle employed was ethanol/propylene
glycol/water, 60/30/10. Treatment was continued for at least 4-5
weeks.
Animals were observed daily for side effects and changes to the
test sites. All observations were documented. Test sites were graded
weekly for changes in skin color and hair growth. In this study
drug effects were evaluated using the visual observation of skin
changing from pink to gray and resulting in hair growth.
Results
The percent of animals that induced hair follicle stimulation during
the treatment period is illustrated in the accompanying Figure below.
The most significant observation made between the two enantiomers
is the difference in the time of onset of follicle stimulation.
The time of onset for the Example 1-(R)-enantiomer was day 7 compared
to day 11 for Example 2-(S)-enantiomer. The time of onset for the
vehicle control was day 28. By day 11 of treatment the Example 1-(R)-enantiomer
caused hair follicle stimulation in 40% of the test mice compared
to only 5% with Example 2-(S)-enantiomer. By day 14, 50% of the
animals treated with Example 1-(R)-enantiomer showed hair follicle
stimulation compared to 25% for Example 2-(S)-enantiomer. By day
28, 85% of the animals treated with the Example 1-(R)-enantiomer
showed hair follicle stimulation as compared to 65% treated with
Example 2-(S)-enantiomer. Thus throughout the treatment period,
the group treated with Example 1-(R)-enantiomer showed a higher
incidence of hair follicle stimulation as compared to the group
treated with Example 2-(S)-enantiomer.
The attached Figure shows the effect of 1.times. daily topical
application of Example 1-(R)-enantiomer and Example 2-(S)-enantiomer.
In conclusion, these results in the C3H mice indicate that there
is a remarkable difference between the Example 1-(R)-enantiomer
and the Example 2-(S)enantiomer in their effect on hair follicle
stimulation; in particular the (R)-enantiomer has a faster onset
of action compared to the corresponding (S)-enantiomer.
These results are indeed surprising and unexpected especially in
view of the vasorelaxant potencies of each of these enantiomers,
which is generally recognized as an indication of hair growth promoting
properties (Side Effects of Vasodilator Therapy, W. A. Pettinger
et al, Hypertension, 1988, Vol. 11, II-34 to II-36, and Minoxidil
Stimulates Cutaneous Blood Flow in Human Balding Scalps: Pharmacodynamics
measured by laser Doppler velocimetry and photopulse plethysmography.
R. C. Wester et al, J. Invest. Dermatol., 184, Vol. 82, 515-517).
Thus, while the IC.sub.50 for vasorelaxant potency of the (R)-enantiomer
is 47.+-.17 nM versus 157.+-.35 nM for the (S)-enantiomer, as seen
above, the hair growth promoting ability of the (R)-enantiomer for
producing hair growth within 11 days of treatment is 8 times greater
than the corresponding (S)-enantiomer.
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