Patent No. 6051594 Methods and formulations for modulating the human sexual response

 

Patent No. 6051594

Methods and formulations for modulating the human sexual response (Lowrey, Apr 18, 2000)

Abstract

The invention is directed to improved methods for modulating the human sexual response by orally administering a formulation of the vasodilator phentolamine to the blood circulation and thereby modulating the sexual response on demand.

Notes:

SUMMARY OF THE INVENTION

The present invention provides improved formulations for modulating the human sexual response in a human by administering a vasodilator agent to the circulation in an amount effective to increase blood flow to the genitalia. According to the invention, modulation of male and female human sexual response is provided on demand by administering an effective vasodilating amount of the agent in an oral formulation. Vasodilating agents useful in the present invention include, but are not limited to, the group consisting of phentolamine mesylate, phentolamine hydrochloride, phenoxybenzamine, yohimbine, organic nitrates (e.g. nitroglycerin), thymoxamine, imipramine, verapamil, isoxsuprine, naftidrofuryl, tolazoline and papaverine. The presently preferred vasodilator agent is phentolamine mesylate. The presently preferred oral formulation comprises in combination, a vasodilator agent in a rapidly dissolving tablet. Preferred rapidly dissolving tablets have a disintegration time of from about 1 minute to about 10 minutes. Most preferred are rapidly dissolving tablets having the disintegration times of less than one minute. Preferred oral doses of phentolamine mesylate in the formulations of the present invention are from about 5 mg to about 80 mg.

The present invention is also directed to a vasodilator formulation comprising in combination, a vasodilator and a chewable tablet.

The present invention is specifically directed to improved methods for treating male impotence, by administering a vasodilator agent in an amount effective to increase blood flow to the penis wherein erectile ability on demand is permitted by oral administration of the vasodilator.

Preferably, the amount of vasodilating agent used in the practice of the invention for treatment of male impotence is effective to improve erectile ability in from about 1 minute to about 60 minutes following administration of the agent.

The invention is also specifically directed to methods for modulating the excitation and plateau phases of the female sexual response on demand by oral administration of an effective amount of vasodilator agent.

The methods of the present invention are also useful in preparation for sexual intercourse by virtue of the ability to modulate the sexual response in both males and females.

The present invention is also directed to the use of a drug having vasodilator activity for the manufacture of a medicament for oral administration to modify, on demand, the sexual response in a human and more particularly to improve erectile ability in response to sexual stimulation. Vasodilator drugs useful for manufacturing the medicament include, but are not limited to, phentolamine mesylate, phentolamine hydrochloride, phenoxybenzamine yohimbine, organic nitrates, thymoxamine, imipramine, verapamil, isoxsuprine, naftidrofuryl, tolazoline, and papaverine.

Numerous other advantages of the present invention will be apparent from the following detailed description of the invention including the accompanying examples and the appended claims.

DETAILED DESCRIPTION

The human sexual response in both the male and female involves a complex interplay between endocrine, neurological and psychological components which result in certain physiological and anatomical responses in both men and women.

While there are obvious differences in the sexual response between men and women, one common aspect of the sexual response is the erectile response. The erectile response in both males and females is result of engorgement of the erectile tissues of the genitalia with blood in response to sexual stimulation (physical, psychological, or both).

The vasculature which serves erectile tissue in both men and women is similar. In particular, in both men and women, the arterial circulation to the erectile tissues of the genitalia derives from the common iliac artery which branches from abdominal aorta. The common iliac artery bifurcates into the internal and external iliac arteries. The internal pudic artery arises from the smaller of two terminal branches of the anterior trunk of the internal iliac artery. In the female, the internal pudic artery branches into the superficial perineal artery which supplies the labia pudenda. The internal pudic artery also branches into the artery of the bulb which supplies the bulbi vestibuli and the erectile tissue of the vagina. The artery of the corpus cavernosum, another branch of the internal pudic artery supplies the cavernous body of the clitoris. Still another branch of the internal pudic artery is the arteria dorsalis clitoridis which supplies the dorsum of the clitoris and terminates in the glans and membranous folds surrounding the clitoris which correspond to the prepuce of the male.

In the male, the internal pudic artery branches into the dorsal artery of the penis (which itself branches into a left and right branch) and the artery of the corpus cavernosum, all of which supply blood to the corpus cavernosum. The dorsal artery of the penis is analogous to the artery dorsalis clitoridis in the female, while the artery of the corpus cavernosum in the male is analogous to the artery of the same name in the female.

The male erectile response is regulated by the autonomic nervous system which controls blood flow to the penis via the interaction of peripheral nerves associated with the arterial vessels in and around the corpus cavernosum. In the non-aroused or non-erect state, the arteries serving the corpus cavernosum are maintained in a relatively constricted state, thereby limiting the blood flow to the corpus cavernosum. However, in the aroused state, the smooth muscles associated with the arteries relax under the influence of catecholamines and blood flow to the corpus cavernosum greatly increases, causing expansion and rigidity of the penis. Brindley, supra (1986) hypothesizes that smooth muscle contraction opens valves through which blood can flow from the corpus cavernosum into the extracavernosal veins. According to Brindley (1986), when the relevant smooth muscles relax, the valves close diminishing venous outflow from the corpus cavernosum. When accompanied by increased arterial blood flow into the corpus cavernosum, this results in engorgement of the corpus cavernosum and an erection.

The pre-orgasmic sexual response in females can be broken down into distinct phases. Both the excitement phase and the plateau phase involve vasodilation and engorgement (vasocongestion) of the genitalia with arterial blood in a manner analogous to the male erectile response.

The excitement phase of the female sexual response is characterized by vasocongestion in the walls of the vagina which leads to the transudation of vaginal fluids and vaginal lubrication. Further, the inner one-third of the vaginal barrel expands and the cervix and the body of the uterus become elevated. This is accompanied by the flattening and elevation of the labia majora and an increase in clitoral size. [Kolodny et al., Textbook of Sexual Medicine, Little and Brown, Boston, Mass. (1979)].

The plateau phase follows the excitement phase in the female sexual response and is characterized by prominent vasocongestion in the outer one-third of the vagina, causing a narrowing of the opening of the vagina and a retraction of the shaft and the glans of the clitoris against the symphysis pubis. These responses are also accompanied by a marked vasocongestion of the labia. [Kolodny, supra (1979)].

The vasocongestive aspects of the female sexual response are not restricted to the genitalia in that areolar engorgement also occurs, sometimes to the extent that it masks the antecedent nipple erection that usually accompanies the excitement phase.

The failure of the erectile response in men to the extent that vaginal penetration and sexual intercourse cannot be achieved is termed impotence. Impotence has numerous possible causes which can be broken down into several general classifications. Endocrine related impotence can result from primary gonadal failure, advanced diabetes mellitus, hypothyroidism, and as one of the secondary sequelae of pituitary adenoma, idiopathic or acquired hypogonadism, hyperprolactinemia and other endocrine abnormalities.

Chronic systemic illnesses such as cirrhosis, chronic renal failure, malignancies and other systemic diseases can also cause impotence. Neurogenic impotence arising in the central nervous system can be caused by temporal lobe disorders caused by trauma, epilepsy, neoplasms and stroke, intramedullary spinal lesions, paraplegia, and demyelinating disorders. Neurogenic causes of impotence arising in the peripheral nervous system include somatic or autonomic neuropathies, pelvic neoplasms, granulomas, trauma, and others. Urologic causes of impotence include complete prostatectomy, local trauma, neoplasms, Peyronie's disease, and others. In addition, as discussed above, a significant percentage of cases of impotence are vasculogenic in nature.

As many as half the cases of male impotence may be psychogenic because there is no readily-ascertainable organic cause for the disorder. Even when there appears to be an underlying organic cause of impotence, psychologic factors may play a role in the disorder.

The present invention is designed to modify the circulatory aspects of the erectile response on demand using vasoactive agents administered to the circulation using a rapidly dissolving orally administered formulation.

A number of vasoactive agents may be used in the practice of the present invention based on demonstrated systemic efficacy as vasodilators. Useful vasodilating drugs include those generally classified as .alpha.-adrenergic antagonists, sympathomimetic amines and those agents which exhibit direct relaxation of vascular smooth muscle. Exemplary .alpha.-adrenergic antagonists include phentolamine, phentolamine hydrochloride, phentolamine mesylate, phenoxybenzamine, tolazoline, dibenamine, yohimbine, and others. Phentolamine mesylate is a preferred .alpha.-adrenergic agent vasodilator for use preferred practice of the present invention. An exemplary sympathomimetic amine contemplated for use in the method of the present invention is nylidrin and use of other sympathomimetic amines having vasodilating activity is also contemplated.

Nicotinic acid (or nicotinyl alcohol) has a direct vasodilating activity useful in the practice of the present invention. Also contemplated is the use of papaverine, a non-specific smooth muscle relaxant which possesses vasodilating activity and which has been used to treat male impotence by direct injection into the corpus cavernosum either alone or in combination with other drugs such as phentolamine. Organic nitrates such as nitroglycerine and amyl nitrate have pronounced vasodilating activity by virtue of their ability to relax vascular smooth muscle and are thus contemplated for use according to the invention. Other vasoactive drugs useful in the practice of the present invention include, without limitation, thymoxamine, imipramine, verapamil, naftidrofuryl, and isoxsuprine.

The formulations also eliminate the need for continuous therapy by providing a single dose for rapidly improving erectile ability on demand.

According to the present invention, the vasodilating agent is administered orally in the form of a rapidly dissolving tablet formulation, a rapidly dissolving chewable tablet formulation, solutions, effervescent formulations, and other orally administered formulations that permit the rapid introduction of the vasodilating substance to the circulation so as to improve erectile ability within a short time (on demand) after administration of a single dose of the agent.

Formulations and methods of the present invention are thus more convenient and help minimize any side-effects that may arise as a result of continuous or daily administration of the drugs. In addition, methods of the present invention allow more spontaneity in sexual activity than allowed by other methods such as the intracavernosal injection of vasodilators.

The examples set forth below are intended to be illustrative of the present invention and are not intended to limit the scope of the invention as set out in the appended claims. The invention is illustrated in the following examples with reference to phentolamine as a vasodilator and in particular, with reference to phentolamine mesylate.

Phentolamine can exist in unsolvated as well as solvated forms, including hydrated forms, e.g., hemi-hydrate. In general, the solvated forms, with pharmaceutically acceptable solvents such as water, ethanol and the like are equivalent to the unsolvated forms for purposes of the invention. Phentolamine can form pharmaceutically acceptable salts with organic and inorganic acids. Examples of suitable acids for salt formation are hydrohamic acids such as hydrochloric and hydrobromic; as well as other acids such as sulfuric, phosphoric, acetic, citric, oxalic, malonic, salicylic, malic, fumaric, succinic, ascorbic, maleic, methanesulfonic, toluenesulfonic, and other mineral and carboxylic acids known to those skilled in the art. The salts are prepared by contacting the free base form with a sufficient amount of the desired acid to produce a salt in the conventional manner. The free base forms may be regenerated by treating the salt with a suitable dilute aqueous base solution such as dilute aqueous sodium hydroxide, potassium carbonate, ammonia and sodium bicarbonate. The free base forms differ from their respective salt forms somewhat in certain physical properties, such as solubility in polar solvents, but the salts are otherwise equivalent to their respective free base form for purposes of this invention. Phentolamine can also form crystalline polymorph forms or crystalline forms thereof using suitable or conventional crystallization procedures.

---------------------------------

While this invention has been described by way of preferred embodiments, the examples set out herein are not intended to limit the scope of the invention which contemplates the use of any pharmacologic vasodilating drug capable of absorption into the systemic circulation upon administration of the drug via an orally administered formulation capable of improving erectile ability on demand.