U.S. patent application number 11/367910 was filed with the patent office on 2006-07-06 for nasal spray steroid formulation and method.
This patent application is currently assigned to Balance Pharmaceuticals, Inc.. Invention is credited to AnnaMarie Daniels, John R. Daniels, Malcolm C. Pike, Darcy V. Spicer.
Application Number | 20060147385 11/367910 |
Document ID | / |
Family ID | 31190803 |
Filed Date | 2006-07-06 |
United States Patent
Application |
20060147385 |
Kind Code |
A1 |
Pike; Malcolm C. ; et
al. |
July 6, 2006 |
Nasal spray steroid formulation and method
Abstract
The present invention relates to an improvement in a method of
contraception, in treatment of benign gynecological disorders, and
in hormone replacement. The improved method includes administering
intranasally an estrogenic compound and an androgenic compound, and
in some embodiments an optional progestin compound, in a once-daily
bolus formulation comprised of the two or three steroids complexed
with a cyclodextrin. An intranasal delivery system for
administration of the formulation is also described.
Inventors: |
Pike; Malcolm C.; (Marina
Del Rey, CA) ; Spicer; Darcy V.; (La Canada, CA)
; Daniels; AnnaMarie; (Pacific Palisades, CA) ;
Daniels; John R.; (Pacific Palisades, CA) |
Correspondence
Address: |
PERKINS COIE LLP
P.O. BOX 2168
MENLO PARK
CA
94026
US
|
Assignee: |
Balance Pharmaceuticals,
Inc.
|
Family ID: |
31190803 |
Appl. No.: |
11/367910 |
Filed: |
March 3, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10295337 |
Nov 15, 2002 |
7029657 |
|
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11367910 |
Mar 3, 2006 |
|
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60400576 |
Aug 2, 2002 |
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Current U.S.
Class: |
424/45 ; 514/170;
514/58 |
Current CPC
Class: |
Y10S 514/841 20130101;
A61K 31/715 20130101; A61K 31/56 20130101; A61K 31/724 20130101;
A61K 31/724 20130101; Y10S 514/874 20130101; A61K 31/56 20130101;
Y10S 514/843 20130101; A61K 31/715 20130101; A61K 2300/00 20130101;
A61K 2300/00 20130101; A61K 2300/00 20130101 |
Class at
Publication: |
424/045 ;
514/058; 514/170 |
International
Class: |
A61K 31/724 20060101
A61K031/724; A61L 9/04 20060101 A61L009/04; A61K 31/56 20060101
A61K031/56 |
Claims
1. An intranasal drug-delivery system for use in contraception, in
treatment of benign gynecological disorders, or in hormone
replacement, by administration of an estrogenic compound and an
androgenic compound, and an optional progestin compound,
comprising: (a) a nasal-spray nebulizer, and (b) contained in the
nebulizer, a formulation comprising an estrogenic compound and an
androgenic compound, said compounds in a solubilized form complexed
with a cyclodextrin, where the amount of the compounds administered
intranasally is such as to produce a biological effect comparable
to that produced when the estrogenic compound and the androgenic
compound are administered transdermally.
2. The system of claim 1, wherein the cyclodextrin is
2-hydroxypropyl-.beta.-cyclodextrin.
3. The system of claim 2, wherein the
2-hydroxypropyl-.beta.-cyclodextrin has a degree of substitution
between 2 and 8.
4. The system of claim 2, wherein the concentration of
2-hydroxypropyl-.beta.-cyclodextrin in the formulation is between
50 to 300 mg/mL.
5. The system of claim 2, wherein the estrogenic compound and the
androgenic compound have a combined molar occupancy with respect to
the cyclodextrin that is greater than the molar occupancy
achievable with either steroid alone.
6. The system of claim 2, wherein the estrogenic compound is
17.beta.-estradiol at a daily dose between 0.15 mg and 0.6 mg and
the androgenic compound is testosterone at a daily dose between
0.15 mg and 1.0 mg.
7. The system of claim 6, wherein the mole ratio of 17-.beta.
estradiol to testosterone is between 1:1 and 1:5.
8. The system of claim 1, wherein said formulation further
comprises a progestin compound as a third steroid.
9. The system of claim 1, wherein said nebulizer is effective to
deliver a spray volume of between about 30 .mu.L to 200 .mu.L
10. A method of formulating two or more different steroids in a
water-soluble form suitable for uptake by a human subject through
mucosal tissue, comprising forming an aqueous solution of a
cyclodextrin, adding the steroids to the solution in amounts
effective to achieve a combined molar occupancy of the two or more
steroids which is greater than the molar occupancy achievable with
any of the steroids alone.
11. The method of claim 10, further comprising, prior to said
adding, heating the aqueous solution of cyclodextrin to above about
70.degree. C.
12. The method of claim 10, wherein said adding includes adding the
first steroid to the solution until a maximum or near-maximum molar
occupancy is reached, then adding the second steroid until a
combined maximum or near-maximum molar occupancy is reached.
13. The method of claim 10, wherein the cyclodextrin is
2-hydroxypropyl-.beta.-cyclodextrin and said two or more steroids
are an estrogenic compound and an androgenic compound.
14. The method of claim 13, wherein said estrogenic compound is
17.beta.-estradiol and said androgenic compound is
testosterone.
15. The method of claim 14, wherein said two or more steroids
further comprises a progestin compound as a third steroid.
Description
[0001] This application is a continuation of U.S. application Ser.
No. 10/295,337 filed Nov. 15, 2002, now pending; which claims the
benefit of U.S. Provisional Application No. 60/400,576 filed Aug.
2, 2002, both of which are incorporated herein by reference in
their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to an improvement in a method
of contraception or in treatment of benign gynecological disorders
in conjunction with a GnRH compound, or in hormone replacement for
postmenopausal or surgically postmenopausal women where an
estrogenic compound and an androgenic compound and, optionally, a
progestin compound are administered. The improvement involves
administering the estrogenic compound and the androgenic compound
and, optionally, a progestin compound intranasally in a once-daily
bolus of a formulation comprised of the two or three steroids
complexed with a cyclodextrin.
BACKGROUND OF THE INVENTION
[0003] During a woman's reproductive life, a delicate and complex
interplay of hormones are timed and controlled by the hypothalamus.
The hormones that participate in the feedback system regulating the
menstrual cycle include estrogens and progesterone, the pituitary
gonadotropins FSH (follicle stimulating hormone) and LH
(luteinizing hormone), and gonadotropin-releasing hormone (GnRH)
from the hypothalamus.
[0004] Manipulation of the hormonal balance is a recognized
approach of contraception and of treatment of benign gynecological
disorders. In particular, administration of a GnRH compound for
contraception has been described (U.S. Pat. Nos. 5,340,584;
5,211,952). Typically, the GnRH compound is administered in a slow
or controlled-release fashion for continuous suppression of ovarian
estrogen and progesterone production. Estrogen, often a progestin,
and sometimes an androgen, are "added-back" to ameliorate the
effects of hormonal deficiency. The hormone add-backs are also
often administered in a slow, controlled-release or time-release
fashion to maintain a constant hormonal serum level.
[0005] Treatment of benign gynecological disorders by
administration of a GnRH compound has also been described (U.S.
Pat. Nos. 5,340,584; 5,340,585; 5,681,817). During a women's
reproductive years, defined as the time between onset of menses
(menarche) and the final episode of bleeding (menopause), that is a
premenopausal woman, a variety of benign gynecological disorders
can occur. Common benign gynecological disorders include, but are
not limited to, premenstrual syndrome, endometriosis, uterine
leiomyomata (uterine fibroids), and polycystic ovarian syndrome. As
for contraceptive use, a GnRH compound is administered to suppress
ovarian follicle development and sex steroid production, and for
benign gynecologic disorders, to relieve or treat symptoms
associated with the disorder.
[0006] A woman's endogenous level of estrogen is significantly
reduced upon entering menopause or upon premature surgical
menopause induced by removal of the ovaries. The amount of a
woman's endogenous estrogen is typically reduced to less than about
10% to about 20% of premenopausal levels following natural or
surgical menopause. This reduction of endogenous estrogen levels
results in the loss of estrogen's health protective effects,
particularly with respect to bone mineral density. Estrogen
replacement therapy (ERT) is often utilized as a treatment to
increase the level of estrogen in women having reduced levels of
endogenous estrogen resulting from natural or surgical menopause.
Supplemental estrogen is provided to the women in order to inhibit,
ameliorate, or prevent diseases or conditions which result from the
reduction of endogenous estrogen.
[0007] The administration of drugs by absorption through mucosae,
such as the nasal mucosa or vaginal mucosa, has been of
considerable interest in recent years. This route of drug delivery
is an alternative to oral administration in cases where drugs are
poorly absorbed or are extensively metabolized in the
gastrointestinal tract or subjected to first-pass metabolism in the
liver. In particular, nasal mucosa has the desirable properties of
being highly vascular leading to rapid uptake and of avoidance of
first-pass metabolism in the liver, since the venous system from
the nose passes directly into the systemic circulatory system. The
nasal mucosa also exhibits moderate permeability to water-soluble
compounds, comparable to that of the ileum. The permeability of
nasal mucosa is higher for most compounds than other mucosa, due in
part to the difference in structure of the cells lining the body
cavities.
[0008] Efficiency of delivery of drugs by an intra-nasal route is
influenced by the degree and rapidity of enzymatic degradation, the
nasal clearance rate, as well as the drug's permeability through
the mucosa. The clearance rate is produced by the coordinated
movement of cilia and is known to be highly dependent upon the
prevailing physiological and pathological conditions. Thus, for
many drugs administration intranasally is inefficient due to low
uptake of the drug, hence low bioavailability.
[0009] Another potential problem associated with intranasal
delivery is mucosal irritation. Irritation caused by the drug
itself and/or by absorption or penetration promoters or enhancers
often limits the success of nasal formulations. Chronic
administration of irritating nasal formulations can cause necrosis,
inflammation, exudation, removal of the epithelial monolayer or can
lead to irreversible damage to the nasal mucosa.
[0010] Nasal formulations for delivery of female sex hormones have
been described (see, for example, U.S. Pat. Nos. 4,596,795;
5,089,482). However, formulations comprised of an estrogenic
compound and an androgenic compound such as testosterone that are
therapeutically effective when delivered intranasally and that are
sufficiently non-irritating to the nasal mucosa for commercial
viability have not been described.
SUMMARY OF THE INVENTION
[0011] Accordingly, it is an object of the invention to provide a
nasal preparation having an estrogenic compound and an androgenic
compound and, and an optional progestin compound, in the form of a
complex with a cyclodextrin.
[0012] It is another object of the invention to provide a
bolus-form of delivery of a composition comprised of an estrogenic
compound and an androgenic compound and, optionally a progestin
compound, that offers a therapeutic activity similar to that of a
slow-release composition of the same active agents, with similar
hormonal areas under the curves (AUCs) in a concentration-time plot
of the two formulations or in achieving a similar biological effect
such as amelioration of symptoms related to sex-steroid
deprivation, specifically, loss of bone mineral density, atrophic
vaginitis, and vasomotor instability.
[0013] In one aspect, the invention includes improvements in
methods for contraception, for treatment of benign gynecological
disorders, both in conjunction with a GnRH compound, and for
hormone replacement for post-menopausal or
surgically-postmenopausal women, where an estrogenic compound and
an androgenic compound, such as testosterone, and an optional
progestin compound, are administered, often on a long-term basis of
longer than about 6 to about 12 months. The improvement comprises
administering the estrogenic compound and the androgenic compound
(an the optional progestin compound when present) intranasally in a
once-daily bolus of an aqueous formulation containing the two or
three compounds in the form of soluble complexes with a
cyclodextrin. The amount of the two or three compounds administered
is such as to produce estrogen and androgen and, optionally,
progestin serum concentrations levels having substantially the same
area-under-the-curve concentrations as are produced when
therapeutically effective doses of the two or three compounds are
administered transdermally. That is, administration of the
estrogenic compound and the androgenic compound and, optionally, a
progestin compound intranasally in bolus form achieves the same
desired biological effect as that produced when the two or three
compounds are administered transdermally.
[0014] The method of the invention, when used for treatment of a
benign gynecological disorder or for contraception in conjunction
with a GnRH compound, in one embodiment, includes administering the
GnRH compound by any suitable route of administration, which may be
different than an intranasal route employed for administration of
the estrogenic compound and the androgenic compound and, optionally
a progestin compound. The GnRH compound can be administered
simultaneously or sequentially.
[0015] In one embodiment, the cyclodextrin is
2-hydroxypropyl-.beta.-cyclodextrin and is present at a
concentration between about 50 mg/mL and 300 mg/mL. In another
embodiment, 2-hydroxypropyl-.beta.-cyclodextrin has a degree of
substitution of between 2 and 8, more preferably between 5 and
8.
[0016] In another embodiment, the estrogenic compound is
17.beta.-estradiol and the androgenic compound is testosterone and
together they have a combined molar occupancy with respect to the
cyclodextrin that is greater than the molar occupancy achievable
with either steroid alone. For example, the combined molar
occupancy of the two steroids is greater than 50%, in one
embodiment. In another embodiment, the combined molar occupancy of
the two steroids is greater than 60%.
[0017] In another embodiment, the estrogenic compound is
17.beta.-estradiol at a daily dose between 0.15 mg and 0.6 mg and
the androgenic compound is testosterone at a daily dose between
0.15 mg and 1 mg.
[0018] The mole ratio of 17.beta.-estradiol to testosterone is
between 1:1 and 1:2, in some embodiments.
[0019] In yet other embodiments, the molar occupancies of
17.beta.-estradiol and testosterone are greater than 20% and 40%,
respectively.
[0020] In another aspect, the invention includes an intranasal
drug-delivery system for use in contraception or in treatment of
benign gynecological disorders in conjunction with a GnRH compound,
or in hormone replacement for postmenopausal or surgically
postmenopausal women. The system is comprised of (a) a nasal-spray
nebulizer effective to deliver a spray volume of between about 30
to about 200 .mu.L, and (b) contained in the nebulizer, a drug
formulation containing an estrogenic compound and an androgenic
compound such as testosterone and, optionally, a progestin compound
in an aqueous medium, in solubilized form complexed with a
cyclodextrin. The amount of the two or three compounds administered
in the spray volume is such as to produce estrogen and androgen,
and progestin when present, serum concentrations having
substantially the same area-under-the-curve concentrations as those
produced when therapeutically effective doses of the two or three
compounds are administered transdermally. That is, the biological
effect achieved by intranasal administration of the two or three
compounds is comparable to that produced when the two or three
compounds are administered transdermally.
[0021] In one embodiment, the nasal preparation and the system are
used on a long-term basis, i.e., for longer than about 6 months,
more preferably for longer than about 12 months.
[0022] In yet another aspect, the invention includes a method of
formulating two or more different steroids in a water-soluble form
suitable for uptake by a human subject through mucosal tissue. The
method is comprised of forming an aqueous solution of a
cyclodextrin and adding the first, second and, optionally, third
steroid to the solution in amounts effective to achieve a combined
molar occupancy of the two or three steroids which is greater than
the molar occupancy achievable with any single steroid alone.
[0023] In one embodiment, the aqueous solution of cyclodextrin is
heated to above about 70.degree. C. prior to said adding, and the
solution is cooled slowly after solubilization of the added
steroids.
[0024] In another embodiment, the first steroid is added to the
solution until a maximum or near-maximum molar occupancy is
reached, then the second and, optionally a third steroid, is/are
added until a combined maximum or near-maximum molar occupancy is
reached.
[0025] The cyclodextrin can be 2-hydroxypropyl-.beta.-cyclodextrin,
the estrogenic compound can be 17.beta.-estradiol, the second
steroid can be testosterone, and the third steroid can be
progesterone.
[0026] These and other objects and features of the invention will
be more fully appreciated when the following detailed description
of the invention is read in conjunction with the accompanying
examples and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is a bar graph showing the molar ratio of steroid to
2-hydroxypropyl-.beta.-cyclodextrin for testosterone
(T/HP.beta.CD), for 17.beta.-estradiol (E2/HP.beta.CD), and for
testosterone and 17.beta.-estradiol in combination where the two
steroids are added to the to 2-hydroxypropyl-.beta.-cyclodextrin
solution simultaneously (T+E2/HP.beta.CD) or added sequentially (E2
then T/HP.beta.CD).
DETAILED DESCRIPTION OF THE INVENTION
I. Nasal Formulation for Use in the Method
[0028] As noted above, the invention includes a nasal preparation
for use in a variety of treatment modalities. For example, the
nasal preparation finds use as add-back hormone replacement in
women who have hormone production suppressed with a gonadotropin
releasing hormone (GnRH) compound. "GnRH compound" refers to
peptide and non-peptide GnRH analogs, including agonists and
antagonists. These compounds are administered, for example, for
female contraception and in the treatment of benign gynecological
disorders. Thus, women currently taking a GnRH compound for
treatment of a benign gynecological disorder or for contraception
are candidates for treatment with the nasal preparation described
herein. The nasal preparation also is suitable for use in hormone
replacement therapy for both postmenopausal and surgically
postmenopausal women. The nasal preparation is also suitable in
perimenopausal women, i.e., women entering menopause who have a low
hormone level, and in women with a low hormone level as a result of
another condition, disorder, or treatment regimen. The nasal
preparation suitable for these various situations and conditions
will now be described.
[0029] A1. Composition Components: Estrogenic Compound
[0030] The composition for use in the method of the invention
includes an estrogenic compound. The estrogenic compound is
effective to prevent one or more of the clinically recognized
symptoms or signs of estrogen deficiency, including but not limited
to bone loss, vaginal atrophy, and hot flashes.
[0031] The estrogenic compound can be a single-component natural or
synthetic estrogen composition, or a combination of such compounds.
As used herein, the term "estrogenic compound" refers to both
natural and synthetic materials having activity to mitigate the
signs and symptoms of estrogen deficiency. Natural and synthetic
estrogenic compositions which can be used according to the
invention described herein include natural estrogenic hormones and
congeners, including but not limited to estradiol, estradiol
benzoate, estradiol cypionate, estradiol valerate, estrone,
diethylstilbestrol, piperazine estrone sulfate, ethinyl estradiol,
mestranol, polyestradiol phosphate, estriol, estriol hemisuccinate,
quinestrol, estropipate, pinestrol, and estrone potassium sulfate.
Equine estrogens, such as equilelinin, equilelinin sulfate, and
estetrol, and synthetic steroids combining estrogenic, androgenic,
and progestogenic properties such as tibolone may also be
employed.
[0032] Typical dose ranges for estrogenic compounds depend on the
compound and on the characteristics of the patient. For an adult
human female patient treated with a transdermal 17.beta.-estradiol
preparation, a typical dose range is one that maintains a serum
level of estradiol of about 25 pg/mL to about 140 pg/mL, more
preferably between about 30 pg/mL to about 50 pg/mL. A specific
example of a composition containing an estrogenic compound is one
comprised of 17.beta.-estradiol and testosterone. The two
compounds, along with other optional excipients, are formulated for
delivery intranasally. For an intranasal preparation, a preferred
dosage range for 17.beta.-estradiol is between about 0.15 mg and
0.6 mg.
[0033] A2. Composition Components: Androgenic Compound
[0034] The composition further includes an androgenic compound. The
androgenic compound is in an amount effective to increase a
patient's androgen level to a level not exceeding a "normal"
premenopausal level, and in particular in concert with the
estrogenic composition to maintain bone mineral density. Such
"normal" androgen levels are on the order of about 15 ng/dL to
about 80 ng/dL for testosterone.
[0035] Suitable androgenic compounds for use in the composition
include but are not limited to testosterone, androstenedione,
dihydrotestosterone, testosterone propionate, testosterone
enanthate, testosterone cypionate, methyltestosterone, danazol,
dromostanolone propionate, ethylestrenol, methandriol, nandrolone
decanoate, nandrolone phenpropionate, oxandrolone, oxymethalone,
and stanozolol.
[0036] Typical dose ranges for androgenic hormones depend upon the
choice of compound and the individual patient. For an adult human
female administered testosterone, typical doses are administered to
provide serum levels of testosterone of from about 15 ng/dL to
about 80 ng/d, and preferably about 40 ng/dL to about 60 ng/dL. For
an intranasal preparation, a typical daily dose can range from
between about 0.15 mg to about 1 mg. The steroid compounds, along
with other optional excipients, are formulated for delivery
intranasally, and exemplary formulations are described below.
[0037] A3. Composition Components: Cyclodextrin Excipient
[0038] In a preferred embodiment, an absorption-promoting component
is included. Exemplary absorption promoting components include
surfactant acids, such as cholic acid, glycocholic acid,
taurocholic acid, and other cholic acid derivatives, chitosan and
cyclodextrins. In a preferred embodiment, a cyclodextrin is
included in the preparation. Cyclodextrins are cyclic
oligosaccharides of .alpha.-D-gluco-pyranose and can be formed by
the catalytic cycilization of starch. Due to a lack of free
rotation about the bonds connecting the glycopyranose units,
cyclodextrins are toroidal or cone shaped, rather than cylindrical.
The cyclodextrins have a relatively hydrophobic central cavity and
a hydrophilic outer surface. The hydrophobic cage-like structure of
cyclodextrins has the ability to entrap a variety of guest
compounds to form host-guest complexes in the solid state and in
solution. These complexes are often termed inclusion complexes and
the guest compounds are released from the inclusion site.
[0039] The most common cyclodextrins are .alpha.-, .beta.-, and
.gamma.-cyclodextrin, which consist of 6, 7, or 8 glucopyranose
units, respectively. Cyclodextrins containing 9, 10, 11, 12, and 13
glucopyranose units are designated .delta.-, .epsilon.-, .xi.-,
.eta.-, and .theta.-cyclodextrin, respectively. Characteristics of
.alpha.-, .beta.-, .gamma.-, and .delta.-cyclodextrin are shown in
Table 1. TABLE-US-00001 TABLE 1 Cyclodextrin Characteristics
.alpha.-cyclo- .beta.-cyclo- .gamma.-cyclo- .delta.-cyclo- dextrin
dextrin dextrin dextrin no. of glucopyranose units 6 7 8 9
molecular weight (Daltons) 972 1135 1297 1459 central cavity
diameter (.ANG.) 4.7-5.3 6.0-6.5 7.5-8.3 10.3-11.2 water solubility
14.5 1.85 23.2 8.19 (at 25.degree. C., g/100 mL)
[0040] Derivatives formed by reaction with the hydroxyl groups
lining the upper and lower ridges of the toroid are readily
prepared and offer a means of modifying the physicochemical
properties of the parent cyclodextrins. The parent cyclodextrins,
and in particular .beta.-cyclodextrin, have limited aqueous
solubility. Substitution of the hydroxyl groups, even with
hydrophobic moieties such as methoxy and ethoxy moieties, typically
increases solubility. Since each cyclodextrin hydroxyl group
differs in chemical reactivity, reaction with a modifying moiety
usually produces an amorphous mixture of positional and optical
isomers. The aggregate substitution that occurs is described by a
term called the degree of substitution. For example, a
2-hydroxypropyl-.beta.-cyclodextrin with a degree of substitution
of five would be composed of a distribution of isomers of
2-hydroxypropyl-.beta.-cyclodextrin in which the average number of
hydroxypropyl groups per 2-hydroxypropyl-.beta.-cyclodextrin
molecule is 5. Degree of substitution can be determined by mass
spectrometry or nuclear magnetic resonance spectroscopy. These
methods do not give information as to the exact location of the
substituents (C1, C2, C3, etc.) or the distribution of the
substituents on the cyclodextrin molecule (mono, di, tri, poly).
Theoretically, the maximum degree of substitution is 18 for
.alpha.-cyclodextrin; 21 for .beta.-cyclodextrin; and 24 for
.gamma.-cyclodextrin, however, substituents with hydroxyl groups
present the possibility for additional hydroxylalkylations.
[0041] The cyclodextrin used in the present invention is preferably
an .alpha.-, .beta.-, or .gamma.-cyclodextrin. The cyclodextrin is
selected for use depending on which cyclodextrin binds the guest
compounds and yields the desired bioavailability. In a preferred
embodiment, a derivative of a cyclodextrin is selected, and
derivatives such as hydroxypropyl, dimethyl, and trimethyl
substituted cyclodextrins are contemplated, as are cyclodextrins
linked with sugar molecules, sulfonated cyclodextrins, carboxylated
cyclodextrins, and amino derivatives such as diethylamino
cyclodextrins. In a preferred embodiment, the cyclodextrin is
.beta.-cyclodextrin, and in a more preferred embodiment, the
cyclodextrin is 2-hydroxypropyl-.beta.-cyclodextrin. In yet another
embodiment, the 2-hydroxypropyl-.beta.-cyclodextrin has a degree of
substitution between 2 and 8, more preferably between 4 and 8, most
preferably between 5 and 8. Exemplary formulations that include the
cyclodextrin 2-hydroxypropyl-.beta.-cyclodextrin are described
below.
[0042] A4. Composition Components: Progestin Compound
[0043] The composition comprised of an estrogenic compound and an
androgenic compound can optionally include a progestin.
Formulations that include a progestin can be administered for a
limited period of time, for example on the order of 5 to 20 days,
and preferably 10 to 15 days after each extended treatment regimen
with a composition comprised of an estrogenic compound and an
androgenic compound. The extended treatment regimen, during which
the estrogenic and androgenic compounds are administered, is
typically for at least about 4 months, more preferably for greater
than about 6 months, and more specifically, of from about 4 months
to about 12 months. The progestin is provided for a limited time
period after such an extended time period. The progestin is given
in an amount effective to minimize or eliminate the occurrence of
endometrial hyperplasia or to preserve the efficacy achieved with
hormone suppression by GnRH compounds in certain benign gynecologic
disorders such as endometriosis and uterine fibroids by
substantially reducing the possibility of endometrial
hyperstimulation which may occur during prolonged treatment with
estrogenic steroids without a progestin.
[0044] Suitable progestational agents (progestins) include but are
not limited to dydrogesterone, ethynodiol diacetate,
hydroxyprogesterone caproate, medroxyprogesterone acetate,
norethindrone, norethindrone acetate, norethynodrel, norgestrel,
progesterone, and megestrol acetate. Typical dose ranges for
progestins depend upon the choice of steroid and the individual
patient. Doses are selected as adequate to produce a secretory
uterine endothelium after the time interval of progestin treatment
(about 5 to about 20 contiguous days, and preferably about 10 to
about 15 contiguous days). The serum level of progesterone is
generally less than about 50 ng/dL after the time interval of
progestin treatment.
[0045] B. Exemplary Nasal Preparations
[0046] As noted above, the composition comprised of an estrogenic
compound and an androgenic compound and, optionally, a progestin
compound complexed with a cyclodextrin are mucosally administered
by contacting the composition in a suitable dosage form with
mucosal tissue of the vagina, nose, rectum, or mouth. In a
preferred embodiment, the composition is administered via the nasal
mucosa, i.e., intranasally. The nasal mucosa provides a useful
anatomical site for systemic delivery. The nasal tissue is highly
vascularized, providing an attractive site for rapid and efficient
absorption. The adult nasal cavity has a capacity of around 20 mL,
with a large surface area of approximately 180 cm.sup.2 for drug
absorption, due in part to the microvilli present along the
psuedostratified columnar epithelial cells of the nasal mucosa.
[0047] A nasal preparation comprised of the composition described
above can take a variety of forms for administration in nasal
drops, nasal spray, gel, ointment, cream, powder or suspension,
using a dispenser or other device as needed. A variety of
dispensers and delivery vehicles are known in the art, including
single-dose ampoules, atomizers, nebulizers, pumps, nasal pads,
nasal sponges, nasal capsules, and the like.
[0048] More generally, the preparation can take a solid,
semi-solid, or liquid form. In the case of a solid form, the
components may be mixed together by blending, tumble mixing,
freeze-drying, solvent evaporation, co-grinding, spray-drying, and
other techniques known in the art. Such solid state preparations
preferably provide a dry, powdery composition with particles in the
range of between about 20 to about 500 microns, more preferably
from 50 to 250 microns, for administration intranasally.
[0049] A semi-solid preparation suitable for intranasal
administration can take the form of an aqueous or oil-based gel or
ointment. For example, the components described above can be mixed
with microspheres of starch, gelatin, collagen, dextran,
polylactide, polyglycolide, or other similar materials that are
capable of forming hydrophilic gels. The microspheres can be loaded
with drug, and upon administration form a gel that adheres to the
nasal mucosa.
[0050] In a preferred embodiment, the nasal preparation is in
liquid form, which can include an aqueous solution, an aqueous
suspension, an oil solution, an oil suspension, or an emulsion,
depending on the physicochemical properties of the composition
components. The liquid preparation is administered as a nasal spray
or as nasal drops, using devices known in the art, including
nebulizers capable of delivering selected volumes of formulations
as liquid-droplet aerosols. For example, a commercially available
spray pump with a delivery volume of 50 .mu.L or 100 .mu.L is
available from, for example, Valois (Congers, N.Y.) with spray tips
in adult size and pediatric size. In one embodiment, the
composition comprised of an estrogenic compound and testosterone
are co-administered intranasally via an aerosol spray in a daily
volume of between about 10 to 500 .mu.L, more preferably between
about 30 to about 200 .mu.L.
[0051] The liquid preparation can be produced by known procedures.
For example, an aqueous preparation for nasal administration can be
produced by dissolving, suspending, or emulsifying the steroid
compounds in water, buffer, or other aqueous medium, or in a
oleaginous base, such as a pharmaceutically-acceptable oil like
olive oil, lanoline, silicone oil, glycerine fatty acids, and the
like.
[0052] It will be appreciated that excipients necessary for
formulation, stability, and/or bioavailability can be included in
the preparation. Exemplary excipients include sugars (glucose,
sorbitol, mannitol, sucrose), uptake enhancers (chitosan),
thickening agents and stability enhancers (celluloses, polyvinyl
pyrrolidone, starch, etc.), buffers, preservatives, and/or acids
and bases to adjust the pH, and the like.
[0053] In a study performed in support of the invention, the
solubility of the steroids 17.beta.-estradiol and testosterone,
alone and in combination, in varying concentrations of
2-hydroxypropyl-.beta.-cyclodextrin was determined. As described in
Example 1, defined amounts of each steroid were added to 1 mL of
2-hydroxypropyl-.beta.-cyclodextrin in water. The solubility of the
steroids was determined, and the results are shown in Tables 2A and
2B.
[0054] Table 2A shows the solubility of 17.beta.-estradiol and
testosterone individually in aqueous solutions of
2-hydroxypropyl-.beta.-cyclodextrin. The last two columns in the
Table 2A show the molar ratio of each steroid to the cyclodextrin.
The molar occupancy of 17.beta.-estradiol with respect to
2-hydroxypropyl-.beta.-cyclodextrin averages approximately 0.21.
The molar occupancy of testosterone with respect to
2-hydroxypropyl-.beta.-cyclodextrin averages approximately 0.39.
TABLE-US-00002 TABLE 2A Solubility of 17.beta.-Estradiol and
Testosterone as Single Agents in
2-Hydroxypropyl-.beta.-cyclodextrin 17.beta.-Estradiol Testosterone
Molar Ratio HP.beta.CD* solubility solubility Estradiol/
Testosterone/ (mg/mL) (mg/mL) (mg/mL) HP.beta.CD HP.beta.CD 10
0.414 0.810 0.21 0.39 40 1.605 2.541 0.20 0.30 70 2.763 5.626 0.20
0.38 100 4.062 6.819 0.21 0.33 130 5.494 11.649 0.21 0.43 160 6.841
13.866 0.22 0.41 190 8.379 16.522 0.22 0.42 220 9.33 18.604 0.21
0.40 250 11.031 21.684 0.22 0.41
*2-hydroxy-propyl-.beta.-cyclodextrin
[0055] Table 2B shows the solubility of 17.beta.-estradiol as a
first steroid and testosterone as a second steroid in aqueous
2-hydroxypropyl-.beta.-cyclodextrin. The last three columns show
the molar ratios of each steroid individually in the
2-hydroxypropyl-.beta.-cyclodextrin solution and of the two
steroids together in the solution. The data show that the combined
molar occupancy of the two steroids together, average approximately
0.48, is greater than the molar occupancy achieved with either
steroid alone (Table 2A). TABLE-US-00003 TABLE 2B Molar Occupancy
of 17.beta.-Estradiol and Testosterone in Sequential Combination in
2-Hydroxypropyl-.beta.-cyclodextrin 17.beta.-Estradiol and
Testosterone solubility Molar Ratio (mg/mL) Estradiol &
HP.beta.CD* Estra- Testos- Estradiol/ Testosterone/ Testosterone/
(mg/mL) diol terone HP.beta.CD HP.beta.CD HP.beta.CD 10 0.164 0.658
0.08 0.31 0.40 40 0.834 2.819 0.11 0.34 0.44 70 1.562 5.073 0.11
0.35 0.46 100 2.157 7.113 0.11 0.34 0.45 130 3.202 10.552 0.12 0.39
0.51 160 4.053 13.422 0.13 0.40 0.53 190 4.796 15.742 0.13 0.40
0.52 250 5.774 19.986 0.12 0.38 0.50
*2-hydroxypropyl-.beta.-cyclodextrin
[0056] The molar ratio data of Tables 2A and 2B are presented
graphically in FIG. 1. FIG. 1 is a bar graph showing the molar
ratio of steroid to 2-hydroxypropyl-.beta.-cyclodextrin for
testosterone, for 17.beta.-estradiol, and for testosterone and
17.beta.-estradiol in combination, as discussed above with respect
to Tables 2A and 2B and Example 1. The figure also shows the molar
ratio determined in another study where 17.beta.-estradiol was
first added to the aqueous 2-hydroxypropyl-.beta.-cyclodextrin
solution, followed by addition of testosterone. The molar occupancy
of the two steroids in combination is similar, regardless of the
sequence of addition of the steroids to the
2-hydroxypropyl-.beta.-cyclodextrin solution.
[0057] In another study, the solubility of 17.beta.-estradiol and
testosterone, alone and in combination, as a function of degree of
substitution of 2-hydroxypropyl-.beta.-cyclodextrin was evaluated.
Solutions of 2-hydroxypropyl-.beta.-cyclodextrin with degrees of
substitution of 5.5, 6.1, and 6.8 were prepared and the maximum
concentration of 17.beta.-estradiol and testosterone that could be
solubilized was determined. There was a slight trend for the
2-hydroxypropyl-.beta.-cyclodextrin with a lower degree of
substitution to solubilize more steroid.
[0058] Accordingly, the invention provides a method for formulating
two or more steroids in a water-soluble form suitable for uptake
through mucosal tissue of a subject. The selected steroids are
added to an aqueous solution of a cyclodextrin simultaneously or
sequentially, to achieve a molar occupancy of the steroids that is
greater than the molar occupancy of any one of the steroids alone.
The invention contemplates selection of an estrogenic compound, an
androgenic compound, and/or a progestin compound as suitable
steroids. When the steroids are added sequentially, the first
steroid is added in an amount sufficient to reach a maximum or
near-maxiumu molar occupancy of the steroid in the cyclodextrin.
Then the second steroid is added in an amount sufficient to reach
the combined maximum or near-maxiumum molar occupancy of the
steroids in the cyclodextrin. In preparing the formulation, the
solution of cyclodextrin can be heated prior to adding the
steroids, and heating to above about 70.degree. C. is usually
suitable to enhance solubilization if needed. After addition of the
two or more steroids the solution can also be slowly cooled.
[0059] C. In vivo Studies
[0060] In a study performed in support of the invention, the
average serum concentration over 24 hours resulting from
transdermal administration of 17.beta.-estradiol and from
intranasal administration of 17.beta.-estradiol were compared. As
described in Example 3, test subjects received 17.beta.-estradiol
transdermally or intranasally. Transdermal estradiol was
administered using a Noven Vivelle.RTM. or a Noven Vivelle-dot.RTM.
transdermal patch, both at dosages of 50 .mu.g/day. The subjects
treated intranasally received 350 .mu.g estradiol in a liquid spray
delivered once per day. Average concentrations for each of the
patient populations were determined from blood samples, and the
results are summarized in Table 3. TABLE-US-00004 TABLE 3 Average
Estradiol Serum Concentration Over 24 Hours (pg/mL) after Treatment
with Transdermal and Intranasal 17.beta.-Estradiol Average Serum
Concentration over 24 Estradiol Dosage Form Hours (pg/mL)
transdermal, Vivelle .RTM. 50 .mu.g/day patch 34.4 transdermal,
Vivelle-dot .RTM. 50 .mu.g/day patch 36.8 intranasal, 350
.mu.g/spray 37.8
[0061] The average serum estradiol concentration over 24 hours for
women receiving estradiol transdermally from the Vivelle.RTM. patch
was 34.4 pg/mL and from the Vivelle.RTM.-dot patch was 36.8 pg/mL.
The average estradiol concentration for women treated with
intranasal estradiol was 37.8 pg/mL. This study shows that an
estrogenic compound administered as an intranasal bolus achieves a
24 hour average serum concentration comparable to that achieved by
transdermal administration. Thus, in one embodiment the invention
provides a 24 hour average serum concentration of estradiol from an
intranasal bolus dose of estradiol that is within (plus or minus)
about 10% of the 24 hour average estradiol serum concentration
achieved from transdermal estradiol administration. That is, the 24
hour average estradiol serum concentration from intranasal bolus
administration of estradiol is at least about 90% of the 24 hour
average estradiol serum concentration from transdermal
administration of estradiol. This result was surprising since
heretofore it was unknown (i) if a bolus dose would achieve
efficacious blood concentration and (ii) if a bolus dose would
achieve a concentration comparable to that of a controlled-release
transdermal dose. The data shows that an intranasal bolus dose of
an estrogenic compound achieves a therapeutic blood concentration,
and that the concentration is comparable, i.e., is within at least
about 10%, to that achieved by transdermal administration of the
estrogenic compound. The comparable steroid blood concentrations
suggests that the physiologic effect achieved by intranasal
administration is comparable to that produced when the estrogenic
compound and the androgenic compound are administered
transdermally.
[0062] Example 4 describes a study performed in support of the
invention where the efficacy and biologic equivalence between nasal
spray add-back estradiol and transdermal estradiol add-back were
evaluated. Women with endometriosis treated with intranasal
deslorelin (a GnRH compound) were assigned to one of three methods
of estradiol add-back: (1) 50 .mu.g/day estradiol transdermal
patch, (2) 300 pg/day intranasal estradiol, or (3) 300 .mu.g/day
intranasal estradiol with 275 .mu.g/day intranasal testosterone.
Loss of bone mineral density (BMD) is a known side effect of
treatment with GnRH compounds. Thus, BMD of the lumbar spine
(L1-L4) of the test subjects in Example 4 was obtained by
dual-energy X-ray absorptiometry (DEXA) prior to and after six
months of treatment. The results are shown in Table 4 as the ratio
of BMD at the six month time point (BMD.sub.6mo.) to the BMD prior
to treatment (BMD.sub.baseline). The BMD of subjects treated with
deslorelin alone in another study is also shown in Table 4 for
comparison. TABLE-US-00005 TABLE 4 Effect of Add-back
17.beta.-Estradiol on the Ratio of 6 Month BMD to Baseline BMD Mean
N Deslorelin (D) 0.971 36 Deslorelin + Transdermal Estradiol 0.978
5 Deslorelin + Intranasal Estradiol 0.996 7 Desloreoin + Intranasal
Estradiol + 0.999 8 Testosterone
[0063] A reduction in loss of BMD by addition of estradiol to
deslorelin is apparent, since all subjects treated with estradiol
had reduced bone loss. The data also shows that estradiol add-back
in the form of an intranasal bolus is at least as effective, and in
fact slightly more effective, in preventing loss of BMD than a
transdermal estradiol add-back, as observed by comparing the BMD
ratios for women receiving estradiol transdermally
(BMD.sub.6mo./BMD.sub.baseline=0.978) and for women receiving
estradiol intranasally (BMD.sub.6mo./BMD.sub.baseline=0.996). Thus,
estradiol added-back in the form of an intranasal bolus dose
reduces the loss of BMD. A nasal spray preparation comprised of an
estrogenic compound, where the preparation has an 24 hour average
estrogenic compound serum concentration (AUC) within 10% of the 24
hour average transdermal estrogenic compound serum concentration
(Table 3), was at least as effective, and preferably more
effective, in preventing loss of BMD than an add-back estrogenic
compound in the form of a transdermal patch.
[0064] In another study, five women were treated with intranasal
testosterone. In this study, 250 .mu.g testosterone was formulated
into a nasal preparation that also contained deslorelin and
estradiol (similar to the procedure in Example 2). The preparation
was administered initially on day one of the study, and then again
one week later on day 8 of the study. The average testosterone
serum concentrations over 24 hours are shown in Table 5.
TABLE-US-00006 TABLE 5 Testosterone: Average Concentration Over 24
Hours After Intranasal Administration of 250 .mu.g Testosterone
(average concentration Subject Number Treatment Day over 24 hours,
ng/dL) 1 Day 1 26.7 Day 2 24.1 2 Day 1 26.7 Day 2 29.9 3 Day 1 19.0
Day 2 17.1 4 Day 1 18.8 Day 2 16.5 5 Day 1 19.1 Day 2 16.2 Average
of both observations in each of 21.4 the 5 subjects
[0065] The average testosterone serum concentration over 24 hours
for both doses in the five subjects was 21.4 ng/dL. This
concentration is comparable to literature reported AUC values
achieved from transdermal administration of testosterone. For
example, in Javanbakht et al. (J. of Clinical Endocrinology and
Metabolism, 85(7):2935 (2000) women wearing a transdermal 300
.mu.g/day testosterone patch for 96 hours had an average serum
concentration of 15.8 ng/dL. Thus, the nasal formulation of the
present invention, i.e., a bolus dose of testosterone, provides a
similar area under the curve as a slow release transdermal
formulation, as evidenced by similar average serum concentration
values over a 24 hour period of time.
[0066] In one embodiment, the intranasal dose of the estrogenic
compound achieves a transient serum level outside the serum
estradiol level of between about 25 pg/mL to about 140 pg/mL that
is typically reported in the literature with a 50 .mu.g/day
transdermal patch. Although the serum hormone level resulting from
intranasal delivery of the hormone is transiently outside this
range a similar beneficial effect is achieved. That is, the
biological effect(s) resulting from intranasal delivery of an
estrogenic compound is similar to the biological effect associated
with a serum estradiol level of between about 25 pg/mL to 140 pg/mL
even though the actual transient serum level may be outside this
range. Thus, in one embodiment, the invention contemplates
administration of an estrogenic compound in an amount sufficient to
achieve the beneficial biological effects that are associated with
a steady estradiol serum level of between about 25 pg/mL to 140
pg/mL, more preferably between about 30 pg/mL to about 100 pg/mL,
most preferably, between about 30 pg/mL to about 50 pg/mL.
[0067] Similarly, the transient testosterone serum blood level
achieved may be lower or higher than that typically obtained by
other routes of administration. However, the physiological
beneficial effects achieved by intranasal administration are
similar to those obtained from a serum testosterone level of
between about 15 ng/dL to about 80 ng/dL, more preferably between
about 40 ng/dL to 60 ng/dL.
[0068] A comparison of the total area under concentration-time
curves (AUC) or average concentrations of serum estradiol and
testosterone in subjects treated with intranasal estradiol and
testosterone to patients treated with estradiol and testosterone by
another route, such as transdermal, provides a basis for
determining the biological equivalency of different routes of
administration. Where the AUCs or average concentrations are
similar, despite different routes of administration or different
concentration-time profiles, the biological effect achieved is
often similar. Thus, in one embodiment, the invention contemplates
achieving by intranasal administration of the disclosed composition
an average serum estradiol concentration over 24 hours of between
about 25 pg/mL and about 50 pg/mL. The invention further
contemplates achieving an average serum testosterone concentration
over 24 hours of between about 15 ng/dL and about 40 ng/dL.
[0069] In a preferred embodiment, the nasal formulation comprising
the estrogenic and androgenic compounds, as first and second
steroids, is an aqueous preparation that is administered as a
once-daily bolus. As noted above, the preparation can optionally
include as a third steroid a progestin compound. The two or three
steroids are complexed with a cyclodextrin to form a water-soluble
complex.
[0070] From the foregoing, it can be seen how various objects and
features of the invention are met. Contraception and treatment of
benign gynecologic disorders, both in conjunction with a GnRH
compound, can be complimented by administration of add-back
steroids delivered in the form of an intranasal preparation.
Hormone replacement therapy can also be achieved by intranasal
delivery of steriods. More specifically, an estrogenic compound and
an androgenic compound and, an optional a progestin compound, are
complexed with cyclodextrin to form a water-soluble complex of the
two or three steroids in the cyclodextrin. The preparation when
administered intranasally has minimal, if any, nasal irritation,
and achieves a 24 hour serum steroid concentration that is within
about 10% of the 24 hour serum steroid concentration observed from
transdermal administration of the steroids.
III. EXAMPLES
[0071] The following examples further illustrate the invention
described herein and are in no way intended to limit the scope of
the invention.
Example 1
Solubility of 17.beta.-Estradiol and Testosterone with
2-Hydroxypropyl-.beta.-cyclodextrin in Water
[0072] The solubility of 17.beta.-estradiol and testosterone in
varying concentrations of 2-hydroxypropyl-.beta.-cyclodextrin (MW
1380 g/mole; 5.5 degree of substitution) was determined as follows.
10 ng 17.beta.-estradiol (MW 272.39 g/mole) was added to 1 mL of
2-hydroxypropyl-.beta.-cyclodextrin in water, the
2-hydroxypropyl-.beta.-cyclodextrin concentration ranging from 10
to 250 ng/mL. In a second series of vials, 20 ng of testosterone
(MW 288.43 g/mole) was added to 1 mL of
2-hydroxypropyl-.beta.-cyclodextrin in water, the
2-hydroxypropyl-.beta.-cyclodextrin concentration ranging from 10
to 250 ng/mL. In a third set of vials 10 ng 17.beta.-estradiol and
20 ng testosterone were added to 1 mL of
2-hydroxypropyl-.beta.-cyclodextrin in water, the
2-hydroxypropyl-.beta.-cyclodextrin concentration ranging from 10
to 250 ng/mL. The vials were mixed at room temperature for about 1
hour. Aliquots were taken from the supernatant of each vial and
assayed for steroid concentration. The results are shown in Tables
2A and 2B.
Example 2
Preparation of Intranasal Formulation
[0073] 2-Hydroxypropyl-.beta.-cyclodextrin was added to water at a
concentration of 240 mg/mL and stirred until dissolved.
17.beta.-estradiol was then added to the water-cyclodextrin
solution at a concentration of 1.0 mg/mL. The mixture was stirred
until dissolution. Testosterone at a concentration of 5.0 mg/mL was
then added, and after stirring to dissolution benzalkonium chloride
(0.1 mg/mL), ethylene diamine tetra acetic acid (EDTA; 1 mg/mL),
and sorbitol (61.6 mg/mL) were added. The mixture was stirred. The
volume was brought to the final desired volume and the pH was
adjusted as needed. Table 6 summarizes the preparation components,
concentrations, and dosages per 50 .mu.L. TABLE-US-00007 TABLE 6
Components in Exemplary Nasal Preparation Concentration Component
(mg/mL) Dose per 50 .mu.L 17.beta.-estradiol 1.0 50 .mu.g
Testosterone 5.0 250 .mu.g 2-hydroxypropyl-.beta.-cyclodextrin 240
12 mg Benzalkonium chloride 0.1 5 .mu.g EDTA 1.0 50 .mu.g Sorbitol
61.6 3.1 mg Water, USP as required
Example 3
Comparison of Intranasally and Transdermally Delivered
Estradiol
[0074] Postmenopausal or surgically-postmenopausal females (n=63)
were recruited for participation in the study. Thirty women were
selected for treatment with transdermal 17.beta.-estradiol from a
Noven Vivelle.RTM. 50 .mu.g/day patch. Thirty women were treated
with transdermal 17.beta.-estradiol from a Noven Vivelle-dot.RTM.
50 .mu.g/day patch. The remaining three women were treated
intranasally with a single 100 .mu.L bolus spray containing 350
.mu.g 17.beta.-estradiol per spray. The spray formulation in
addition to estradiol was comprised of sorbitol (61.6 mg/mL), EDTA
(1.0 mg/mL), benzalkonium chloride (0.1 mg/mL), and
2-hydroxypropyl-.beta.-cyclodextrin (100 mg/mL). Blood samples were
drawn at defined intervals for analysis of serum estradiol levels.
The average concentration of serum estradiol over 24 hours as pg/mL
was determined and the results are shown in Table 3.
Example 4
Intranasal Delivery of GnRH Compound with Transdermal or Intranasal
Co-Administration of Estradiol
[0075] Women with endometriosis treated with intranasal deslorelin
(GnRH compound) were assigned to one of three methods of add-back:
(1) 50 .mu.g/day estradiol transdermal patch, (2) 300 .mu.g/day
intranasal estradiol, or (3) 300 .mu.g/day intranasal estradiol
with 275 .mu.g/day intranasal testosterone. Bone mineral density
(BMD) of the lumbar spine was obtained by dual-energy X-ray
absorptiometry (DEXA) prior to and after six months of drug
treatment. BMD changes are shown in Table 4 as the ratio of the 6
month value compared to the baseline value.
[0076] Although the invention has been described with respect to
particular embodiments, it will be apparent to those skilled in the
art that various changes and modifications can be made without
departing from the invention.
* * * * *