Combination therapy to prevent bone loss-progesterone and estrogen agonists

The present invention provides novel methods of inhibiting bone loss comprising administering to a mammal in need of such treatment an effective amount of a compound of formula I ##STR1## wherein R.sup.1 and R.sup.2 may be the same or different provided that, when R.sup.1 and R.sup.2 are the same, each is a methyl or ethyl group, and, when R.sup.1 and R.sup.2 are different, one of them is a methyl or ethyl group and the other is hydrogen or a benzyl group; or a pharmaceutically acceptable salt thereof; together with a progestin.

BACKGROUND OF THE INVENTION 
Osteoporosis describes a group of diseases which arise from diverse 
etiologies, but which are characterized by the net loss of bone mass per 
unit volume. A consequence of this loss of bone mass is the failure of the 
skeletal frame to provide adequate structural support for the body, 
resulting in bone fracture. One of the most common types of osteoporosis 
occurs in women shortly after menopause. Most women lose between 20-60% of 
the bone mass in the trabecular compartment of the bone within 3-6 years 
after the cessation of menses. This rapid loss of bone mass is generally 
associated with an increase of both bone resorption and formation. The 
resorptive cycle is more dominant, however; and the result is a net loss 
of bone mass. 
Thus, osteoporosis is a common and serious disease among post-menopausal 
women. An estimated 25 million women in the United States alone are 
afflicted with this disease. The results of this disease are both 
personally and economically harmful. Large economic losses are due to its 
chronic nature and the need for extensive and long term support 
(hospitalization and nursing home care) from the disease sequelae. The 
losses are especially great in more elderly patients. Additionally, 
although osteoporosis is not generally considered a life threatening 
condition, there is a 20-30% mortality rate related to hip fractures in 
elderly women. A large percentage of this mortality rate can be directly 
associated with post-menopausal osteoporosis. 
The tissue in the bone most vulnerable to the effects of post-menopausal 
osteoporosis is the trabecular bone. This tissue is often referred to as 
spongy or cancellous bone and particularly concentrated near the ends of 
the bone, near the joints and in the vertebrae of the spine. Trabecular 
tissue is characterized by small osteoid structures which inter-connect 
with each other and with the more solid and dense cortical tissue that 
makes up the outer surface and central shaft of the bone. This criss-cross 
network of trabeculae gives lateral support to the outer cortical 
structure and is critical to the bio-mechanical strength of the overall 
structure. It is primarily the net resorption and loss of the trabeculae 
which leads to the failure and fracture of bone in post-menopausal 
osteoporosis. In light of the loss of the trabeculae in post-menopausal 
women, it is not surprising that the most common fractures are those 
associated with bones which are highly dependent on trabecular support, 
e.g., the vertebrae, the neck of the weight bearing bones (femur) and the 
forearm. Indeed, hip fracture, collies fractures, and vertebral crush 
fractures are hall-marks of post-menopausal osteoporosis. 
A very important concept in the treatment and study of post-menopausal 
osteoporosis is the concept of fracture threshold. The fracture threshold 
is the point at which the bone density (therefore, the bone strength) 
decreases to a value where there is a high probability of bone fracture. 
This point is not a particular value for all women but rather a relative 
number for an individual and is dependent on a number of factors such as 
weight, life-style, or other risks which might contribute to the 
possibility of bone fracture. 
In general, most pre-menopausal women have bone densities above the 
fracture threshold, and there is a low probability that a fracture will 
occur. A woman's pre-menopausal bone density and the rate of bone loss 
after menopause will determine when, or if, she will cross the threshold 
and be at risk for fracture. For women who present with fractures due to 
osteoporosis, ideal therapy would be to increase bone density (strength) 
to a value above the fracture threshold. Alternatively, for women whose 
bone density is still above the threshold, it would be advantageous to 
keep them above it. 
Today, the only available effective treatment for post-menopausal 
osteoporosis is hormone replacement therapy, specifically estrogen 
replacement because post-menopausal women are estrogen deficient. The 
mechanism of action of estrogen in the treatment of osteoporosis is not 
well understood; however, it is generally agreed that it inhibits bone 
resorption. The net effect of the estrogen replacement therapy (ERT) is to 
keep the woman's bone density at the level at which therapy was initiated, 
i.e., it maintains bone density. If a woman is above the fracture 
threshold when (ERT) is initiated, and if ERT is maintained, she will 
remain above the threshold and be at low risk for fracture. This fact 
would argue for the placement of women on ERT at or soon after the 
cessation of menses. 
For women whose bone density has already fallen below the fracture 
threshold, however, ERT will only maintain bone density at the level at 
which they began therapy. Thus, these women will remain below the 
threshold and will be at further risk for fracture. ERT is still advisable 
for these women because it will keep a bad situation from getting worse. 
It would clearly be advantageous, however, to have a therapy which would 
boost bone density above the fracture threshold to more normal levels and 
then maintain it. Currently, there are no effective approved therapies 
which demonstrate an ability to increase bone density to such a level. 
As noted, ERT is now the only effective approved treatment for 
post-menopausal osteoporosis. In those women who do not have a uterus, 
estrogen (usually given as a conjugated form of estrone) can be given by 
itself. In most post-menopausal women who have a uterus, however, 
unopposed estrogen increases the risk of endometrial cancer. Thus, a 
progestin is often also administered, either as a combination or in 
cyclical therapy, to reduce that risk. 
"Antiestrogen" is a term that "has been rather broadly applied to several 
different types of compounds that inhibit or modify the action of 
estrogen. Progestins and androgens have been described as antestrongenic . 
. . " (Goodman and Gilman, The Pharmacological Basis of Therapeutics, 6th 
Ed., p 1431.) In addition, certain synthetic compounds, such as 
tamoxifene, clomiphene, droloxifene and nafoxidine, are called 
antiestrogens and have been shown both experimentally and clinically to 
block some of the effects of estrogen. The synthetic "antiestrogens" were 
principally developed for the treatment of estrogen-dependent breast 
carcinoma. These compounds are classical mixed agonist/antagonists which 
demonstrate some estrogenic activity. For example, tamoxiene, the most 
widely used antiestrogen, has been shown to have estrogenic effects in 
humans. 
The combination of certain 3-benzoyl-benzothiophenes and a progestin has 
been found to be effective in preventing bone loss. EP 665,015 A2. 
SUMMARY OF THE INVENTION 
The present invention relates to methods for inhibiting bone loss 
comprising administering to a mammal in need of such treatment an 
effective amount of a compound of formula I 
##STR2## 
wherein R.sup.1 and R.sup.2 may be the same or different provided that, 
when R.sup.1 and R.sup.2 are the same, each is a methyl or ethyl group, 
and, when R.sup.1 and R.sup.2 are different, one of them is a methyl or 
ethyl group and the other is hydrogen or a benzyl group; or a 
pharmaceutically acceptable salt thereof; together with an effective 
amount of a progestin. Preferred progestins are medroxyprogesterone, 
norethindrone or norethynodrel. A preferred compound of formula I is that 
in which R.sup.1 and R.sup.2 are methyl. A preferred salt is the citrate 
salt. 
DETAILED DESCRIPTION OF THE INVENTION 
The present invention concerns methods for inhibiting bone loss. The term 
"inhibit" is defined to include its generally accepted meaning which 
includes prophylactically treating a subject to prevent the occurrence of 
one or more of these conditions or disease states, holding in check the 
symptoms of such a condition or disease state, and/or treating such 
symptoms. Thus, the present methods include both medical therapeutic 
and/or prophylactic treatment, as appropriate. 
The methods of this invention are practiced by administering to an 
individual in need of treatment an effective amount of a compound formula 
I 
##STR3## 
wherein R.sup.1 and R.sup.2 may be the same or different provided that, 
when R.sup.1 and R.sup.2 are the same, each is a methyl or ethyl group, 
and, when R.sup.1 and R.sup.2 are different, one of them is a methyl or 
ethyl group and the other is hydrogen or a benzyl group; or a 
pharmaceutically acceptable salt thereof; together with an effective 
amount of a progestin selected from medroxyprogesterone, norethindrone and 
norethynodrel. 
Progestins are available from commercial sources and include: Algestone 
Acetophenide, Altrenogest, Amadinone Acetate, Anagestone Acetate, 
Chlormadinone Acetate, Cingestol, Clogestone Acetate, Clomegestone 
Acetate, Delmadinone Acetate, Desogestrel, Dimethisterone, Dydrogesterone, 
Ethynerone, Ethynodiol Diacetate, Etonogestrel, Flurogestone Acetate, 
Gestaclone, Gestodene, Gestonorone Caproate, Gestrinone, Haloprogesterone, 
Hydroxyprogesterone Caproate, Levonorgestrel, Lynestrenol, Medrogestone, 
Medroxyprogesterone Acetate, Melengestrol Acetate, Methynodiol Diacetate, 
Norethindrone, Norethindrone Acetate, Norethynodrel, Norgestimate, 
Norgestomet, Norgestrel, Oxogestone Phenpropionate, Progesterone, 
Quingestanol Acetate, Quingestrone, and Tigestol. 
Preferred progestins are medroxyprogestrone, norethindrone and 
norethynodrel. 
Dosage of progestins is about 0.1 to 10 mg per day; the preferred dose is 
about 0.25 to 5 mg per day in combination with a compound of formula I. 
Compounds of formula I are known in the art and essentially are prepared 
via the methods described in U.S. Pat. No. 5,047,431, which is hereby 
incorporated herein by reference. 
A preferred formula I compound is that in which R.sup.1 and R.sup.2 each 
are methyl. This preferred compound is known as droloxifene, 
(E)-1-[4'-(2-Dimethylaminoethoxy)phenyl]-1-(3-hydroxyphenyl)-2-phenylbut-1 
-ene, which previously has been described as an antiestrogenic agent and is 
useful for the treatment of hormone dependent mammary tumors (U.S. Pat. 
No. 5,047,431), and for the relief of bone diseases caused by the 
deficiency of estrogen or the like (U.S. Pat. No. 5,254,594). Furthermore, 
droloxifene is known to have less uterotrophic effect than other 
antiestrogenic compounds such as tamoxifen. 
Although the free-base form of formula I compounds can be used in the 
methods of the present invention, it is preferred to prepare and use a 
pharmaceutically acceptable salt form. Thus, the compounds used in the 
methods of this invention form pharmaceutically acceptable acid and base 
addition salts with a wide variety of inorganic and, preferably, organic 
acids and include the physiologically acceptable salts which are often 
used in pharmaceutical chemistry. Such salts are also part of this 
invention. Typical inorganic acids used to form such salts include 
hydrochloric, hydrobromic, hydroiodic, nitric, sulfuric, phosphoric, 
hypophosphoric, and the like. Salts derived from organic acids, such as 
aliphatic mono and dicarboxylic acids, phenyl substituted alkanoic acids, 
hydroxyalkanoic and hydroxyalkandioic acids, aromatic acids, aliphatic and 
aromatic sulfonic acids, may also be used. Such pharmaceutically 
acceptable salts thus include acetate, phenylacetate, trifluoroacetate, 
acrylate, ascorbate, benzoate, chlorobenzoate, dinitrobenzoate, 
hydroxybenzoate, methoxybenzoate, methylbenzoate, o-acetoxybenzoate, 
naphthalene-2-benzoate, bromide, isobutyrate, 
phenylbutyrate,.beta.-hydroxybutyrate, butyne-1,4dioate, 
hexyne-1,4-dioate, caprate, caprylate, chloride, cinnamate, citrate, 
formate, fumarate, glycollate, heptanoate, hippurate, lactate, malate, 
maleate, hydroxymaleate, malonate, mandelate, mesylate, nicotinate, 
isonicotinate, nitrate, oxalate, phthalate, terephthalate, phosphate, 
monohydrogenphosphate, dihydrogenphosphate, metaphosphate, pyrophosphate, 
propiolate, propionate, phenylpropionate, salicylate, sebacate, succinate, 
suberate, sulfate, bisulfate, pyrosulfate, sulfite, bisulfite, sulfonate, 
benzenesulfonate, p-bromophenylsulfonate, chlorobenzenesulfonate, 
ethanesulfonate, 2-hydroxyethanesulfonate, methanesulfonate, 
naphthalene-1-sulfonate, naphthalene-2-sulfonate, p-toluenesulfonate, 
xylenesulfonate, tartarate, and the like. A preferred salt is the citrate 
salt. 
The pharmaceutically acceptable acid addition salts are typically formed by 
reacting a compound of formula I with an equimolar or excess amount of 
acid. The reactants are generally combined in a mutual solvent such as 
diethyl ether or benzene. The salt normally precipitates out of solution 
within about one hour to 10 days and can be isolated by filtration or the 
solvent can be stripped off by conventional means. 
The pharmaceutically acceptable salts of formula I compounds generally have 
enhanced solubility characteristics compared to the compound from which 
they are derived, and thus are often more amenable to formulation as 
liquids or emulsions. 
Once prepared, the free base or salt form of formula I compounds and a 
progestin can be administered to an individual in need of treatment for 
the methods herein described. The following nonlimiting test examples 
illustrate the methods of the present invention. 
For the methods of the present invention, compounds of Formula I and a 
progestin are administered continuously, or from 1 to 4 times daily. 
As used herein, the term "effective amount" means an amount of the 
composition used in the methods of the present invention which is capable 
of inhibiting the symptoms of the pathological conditions herein 
described. The specific dose of a compounds administered according to this 
invention will, of course, be determined by the particular circumstances 
surrounding the case including, for example, the compounds administered, 
the route of administration, the state of being of the patient, and the 
severity of the pathological condition being treated. A typical daily dose 
will contain a nontoxic dosage level of from about 0.25 mg to about 100 
mg/day of a composition of the present invention. Preferred daily doses 
generally will be from about 1 mg to about 20 mg/day. The compound of 
formula I will be administered concurrently with about 0.1 mg to 10 mg of 
a progestin. 
The compounds of this invention can be administered by a variety of routes 
including oral, rectal, transdermal, subucutaneous, intravenous, 
intramuscular, and intranasal. These compounds preferably are formulated 
prior to administration, the selection of which will be decided by the 
attending physician. Typically, a formula I compound, or a 
pharmaceutically acceptable salt thereof, is combined with a 
pharmaceutically acceptable carrier, diluent or excipient to form a 
pharmaceutical formulation. 
The total active ingredients in such formulations comprises from 0.1% to 
99.9% by weight of the formulation. By "pharmaceutically acceptable" it is 
meant the carrier, diluent, excipients, and/or salt must be compatible 
with the other ingredients of the formulation, and not deleterious to the 
recipient thereof. 
Pharmaceutical formulations containing a compound of formula I can be 
prepared by procedures known in the art using well known and readily 
available ingredients. For example, the compounds of formula I can be 
formulated with common excipients, diluents, or carriers, and formed into 
tablets, capsules, suspensions, powders, and the like. Examples of 
excipients, diluents, and carriers that are suitable for such formulations 
include the following fillers and extenders such as starch, sugars, 
mannitol, and silicic derivatives binding agents such as carboxymethyl 
cellulose and other cellulose derivatives, alginates, gelatin, and 
polyvinyl-pyrrolidone; moisturizing agents such as glycerol; 
disintegrating agents such as calcium carbonate and sodium bicarbonate 
agents for retarding dissolution such as paraffin resorption accelerators 
such as quatemary ammonium compounds; surface active agents such as cetyl 
alcohol, glycerol monostearate; adsorptive carriers such as kaolin and 
bentonite; and lubricants such as talc, calcium and magnesium stearate, 
and solid polyethyl glycols. 
The compounds also can be formulated as elixirs or solutions for convenient 
oral administration or as solutions appropriate for parenteral 
administration, for example, by intramuscular, subcutaneous or intravenous 
routes. 
Additionally, the compounds are well suited to formulation as sustained 
release dosage forms and the like. The formulations can be so constituted 
that they release the active ingredient only or preferably in a particular 
physiological location, possibly over a period of time. The coatings, 
envelopes, and protective matrices may be made, for example, from 
polymeric substances or waxes. 
Compounds of formula I and progestin generally will be administered in a 
convenient formulation. The following formulation examples only are 
illustrative and are not intended to limit the scope of the present 
invention. 
In the formulations which follow, "active ingredient" means a compound of 
formula 1, or a salt thereof; and a progestin. 
Formulation 1: Gelatin Capsules 
Hard gelatin capsules are prepared using the following: 
______________________________________ 
Quantity 
Ingredient (mg/capsule) 
______________________________________ 
Active ingredient 0.25-100 
Starch, NF 0-650 
Starch flowable powder 
0-50 
Silicone fluid 350 centistokes 
0-15 
______________________________________ 
A tablet formulation is prepared using the ingredients below: 
Formulation 2: Tablets 
______________________________________ 
Quantity 
Ingredient (mg/tablet) 
______________________________________ 
Active ingredient 0.25-100 
Cellulose, microcrystalline 
200-650 
Silicon dioxide, fumed 
10-650 
Stearate acid 5-15 
______________________________________ 
The components are blended and compressed to form tablets. 
Alternatively, tablets each containing 0.25-100 mg of active ingredient are 
made up as follows: 
Formulation 3: Tablets 
______________________________________ 
Quantity 
Ingredient (mg/tablet) 
______________________________________ 
Active ingredient 0.25-100 
Starch 45 
Cellulose, microcrystalline 
35 
Polyvinylpyrrolidone 
4 
(as 10% solution in water) 
Sodium carboxymethyl cellulose 
4.5 
Magnesium stearate 0.5 
Talc 1 
______________________________________ 
The active ingredient, starch, and cellulose are passed through a No. 45 
mesh U.S. sieve and mixed thoroughly. The solution of polyvinylpyrrolidone 
is mixed with the resultant powders which are then passed through a No. 14 
mesh U.S. sieve. The granules so produced are dried at 
50.degree.-60.degree. C. and passed through a No. 18 mesh U.S. sieve. The 
sodium carboxymethyl starch, magnesium stearate, and talc, previously 
passed through a No. 60 U.S. sieve, are then added to the granules which, 
after mixing, are compressed on a tablet machine to yield tablets. 
Suspensions each containing 0.25-100 mg of medicament per 5 ml dose are 
made as follows: 
Formulation 4: Suspensions 
______________________________________ 
Quantity 
Ingredient (mg/5 ml) 
______________________________________ 
Active ingredient 0.25-100 mg 
Sodium carboxymethyl cellulose 
50 mg 
Syrup 1.25 mg 
Benzoic acid solution 0.10 mL 
Flavor q.v. 
Color q.v. 
Purified Water to 5 mL 
______________________________________ 
The medicament is passed through a No. 45 mesh U.S. sieve and mixed with 
the sodium carboxymethyl cellulose and syrup to form smooth paste. The 
benzoic acid solution, flavor, and color are diluted with some of the 
water and added, with stirring. Sufficient water is then added to produce 
the required volume. An aerosol solution is prepared containing the 
following ingredients: 
Formulation 5: Aerosol 
______________________________________ 
Quantity 
Ingredient (% by weight) 
______________________________________ 
Active ingredient 0.25 
Ethanol 25.75 
Propellant 22 (Chlorodifluoromethane) 
70.00 
______________________________________ 
The active ingredient is mixed with ethanol and the mixture added to a 
portion of the propellant 22, cooled to 30.degree. C., and transferred to 
a filling device. The required amount is then fed to a stainless steel 
container and diluted with the remaining propellant. The valve units are 
then fitted to the container. Suppositories are prepared as follows: 
Formulation 6: Suppositories 
______________________________________ 
Quantity 
Ingredient (mg/suppository) 
______________________________________ 
Active ingredient 250 
Saturated fatty acid glycerides 
2,000 
______________________________________ 
The active ingredient is passed through a No. 60 mesh U.S. sieve and 
suspended in the saturated fatty acid glycerides previously melted using 
the minimal necessary heat. The mixture is then poured into a suppository 
mold of nominal 2 g capacity and allowed to cool. An intravenous 
formulation is prepared as follows: 
Formulation 7: Intravenous Solution 
______________________________________ 
Ingredient Quantity 
______________________________________ 
Active ingredient 20 mg 
Isotonic saline 1,000 mL 
______________________________________ 
The solution of the above ingredients is intravenously administered to a 
patient at a rate of about 1 mL per minute.

EXAMPLE 1 
In these examples, a model of post-menopausal osteoporosis is used in which 
effects of different treatments upon femur density are determined. 
Seventy-five day old female Sprague Dawley rats (weight range of 225 to 275 
g) are obtained from Charles River Laboratories (Portage, Mich.). They are 
housed in groups of 3 and have ad libitum access to food (calcium content 
approximately. 1%) and water. Room temperature is maintained at 
22.2.degree..+-.1.7.degree. C. with a minimum relative humidity of 40%. 
The photoperiod in the room is 12 hours light and 12 hours dark. 
One week after arrival, the rats undergo bilateral ovariectomy under 
anesthesia (44 mg/kg Ketamine and 5 mg/kg Xylazine (Butler, Indianapolis, 
Ind.) administered intramuscularly). Treatment with vehicle or a compound 
of formula I and a progestin is initiated either on the day of surgery 
following recovery from anesthesia or 35 days following the surgery. 
Oral dosage is by gavage in 0.5 mL of 1% carboxymethylcellulose (CMC). 
Body weight is determined at the time of surgery and weekly during the 
study, and the dosage is adjusted with changes in body weight. 
Vehicle-treated ovariectomized (ovex) rats and non-ovariectomized (intact) 
rats are evaluated in parallel with each experimental group to serve as 
negative and positive controls. 
The rats are treated daily for 35 days (6 rats per treatment group) and 
sacrificed by decapitation on the 36th day. The 35-day time period is 
sufficient to allow maximal reduction in bone density, measured as 
described infra. At the time of sacrifice, the uteri are removed, 
dissected free of extraneous tissue, and the fluid contents were expelled 
before determination of wet weight in order to confirm estrogen deficiency 
associated with complete ovariectomy. Uterine weight is routinely reduced 
about 75% in response to ovariectomy. The uteri are then placed in 10% 
neutral buffered formalin to allow for subsequent histological analysis. 
The right femurs are excised and scanned at the distal metaphysis 1 mm from 
the patellar groove with single photon absorptiometry. Results of the 
densitometer measurements represent a calculation of bone density as a 
function of the bone mineral content and bone width.