Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Matrices
Reexamination Certificate
2001-05-15
2003-02-04
Webman, Edward J. (Department: 1617)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Matrices
C424S488000, C424S484000, C514S929000, C514S944000, C514S777000, C514S781000, C514S559000
Reexamination Certificate
active
06514536
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the preparation of a transdermal delivery system. The preparation is designed to deliver therapeutic levels of a drug which causes vasodilation, and optionally prostaglandin E
1
, to specific sites below the dermal level of the skin. Specifically, the preparations address sexual dysfunction caused by impotency in males and vaginal dryness in females.
DESCRIPTION OF THE PRIOR ART
Over the years, methods have been developed to achieve the efficient delivery of a therapeutic drug to a mammalian body part requiring pharmaceutical treatment. Use of an aqueous liquid which can be applied at room temperature as a liquid but which forms a semi-solid gel when warmed to body temperature has been utilized as a vehicle for some drug delivery since such a system combines ease of application with greater retention at the site requiring treatment than would be the case if the aqueous composition were not converted to a gel as it is warmed to mammalian body temperature. In U.S. Pat. No. 4,188,373, PLURONIC® polyols are used in aqueous compositions to provide thermally gelling aqueous systems. Adjusting the concentration of the polymer provides the desired sol-gel transition temperature, that is, the lower the concentration of polymer, the higher the sol-gel transition temperature, after crossing a critical concentration minimum, below which a gel will not form.
In U.S. Pat. Nos. 4,474,751 and 4,478,822, drug delivery systems are described which utilize thermosetting gels; the unique feature of these systems is that both the gel transition temperature and/or the rigidity of the gel can be modified by adjusting the pH and/or the ionic strength, as well as by the concentration of the polymer.
Other patents disclosing pharmaceutical compositions which rely upon an aqueous gel composition as a vehicle for the application of the drug are U.S. Pat. Nos. 4,883,660; 4,767,619; 4,511,563; 4,861,760; and 5,318,780. Thermosetting gel systems are also disclosed for application to injured mammalian tissues of the thoracic or peritoneal cavities in U.S. Pat. No. 4,911,926.
Ionic polysaccharides have been used in the application of drugs by controlled release Such ionic polysaccharides as chitosan or sodium alginate are disclosed as useful in providing spherical agglomerates of water-insoluble drugs in the Journal of Pharmaceutical Sciences, Volume 78, Number 11, November 1989, Bodmeier et al. Calcium alginate gel formulations have also found use as a matrix material for the controlled release of herbicides, as disclosed in the Journal of Controlled Release, (1986), pages 229-233, Pfizer et al.
In U.S. Pat. No. 3,640,741, a molded plastic mass composed of the reaction product of a hydrophilic colloid and a cross-linking agent such as a liquid polyol, also containing an organic liquid medium such as glycerin, is disclosed as useful in the controlled release of medication or other additives. The hydrophilic colloid can be carboxymethyl cellulose gum or a natural alginate gum which is cross-linked with a polyol. The cross-linking reaction is accelerated in the presence of aluminum and calcium salts.
In U.S. Pat. No. 4,895,724, compositions are disclosed for the controlled release of pharmacological macromolecular compounds' contained in a matrix of chitosan. Chitosan can be cross-linked utilizing aldehydes, epichlorohydrin and benzoquinone.
In U.S. Pat. No. 4,795,642, there are disclosed gelatin-encapsulated, controlled-release compositions for release of pharmaceutical compositions, wherein the gelatin encloses a solid matrix formed by the cation-assisted gelation of a liquid filling composition incorporating a vegetable gum together with a pharmaceutically-active compound. The vegetable gums are disclosed as polysaccharide gums such as alginates which can be gelled utilizing a cationic gelling agent such as an alkaline earth metal cation.
While the prior art is silent with respect to aqueous drug delivery vehicles and isotonicity thereof, osmotic drug delivery systems are disclosed in U.S. Pat. No. 4,439,196 which utilize a multi-chamber compartment for holding osmotic agents, adjuvants, enzymes, drugs, pro-drugs, pesticides, and the like. These materials are enclosed by semipermeable membranes so as to allow the fluids within the chambers to diffuse into the environment into which the osmotic drug delivery system is in contact. The drug delivery device can be sized for oral ingestion, implantation, rectal, vaginal, or ocular insertion for delivery of a drug or other beneficial substance. Since this drug delivery device relies on the permeability of the semipermeable membranes to control the rate of delivery of the drug, the drugs or other pharmaceutical preparations by definition, are not isotonic with mammalian blood.
Finding a suitable drug delivery vehicle for the treatment of erectile dysfunction has proven to be particularly difficult. Male erectile dysfunction, the persistent inability of a man to achieve or maintain an erection sufficient for satisfactory sexual performance, is estimated to affect up to 30 million men in the United States. See “Oral Sildenafil in the Treatment of Erectile Dysfunction”,
New England Journal of Medicine,
338:20:1397 (1998). There are numerous causes of male erectile dysfunction. For example, it may be atonic, due to paralysis of the motor nerves without any evidence of lesions to the central nervous system, particularly the spinal cord. Alternatively, it could be psychic, and dependent on a mental problem or instability. Finally, it could be symptomatic, due to some other disorder, such as injury to nerves in the perineal region, by virtue of which the sensory portion of the erection reflex is blocked out.
Various available treatments have been employed in the treatment of male erectile dysfunction, including vacuum-constriction devices, intracavernosal injections of vasoactive agents, transurethral delivery of prostaglandin E
1
(alprostadil), oral administration of sildenafil citrate (Viagra® available from Pfizer), implantation of penile prostheses, and venous or arterial surgery. Most of these treatments involve painful procedures with varying degrees of success that are often associated with numerous side effects. Moreover, many persons are not candidates for one or more of these treatments as a result of their physiological condition. For example, oral admistration of sildenafil citrate is contraindicated for individuals currently taking organic nitrates, such a nitroglycerine. See “VIAGRA® (sildenafil citrate) Tablets”, Pfizer Labs, 7 (1998).
The medications most commonly used to treat male erectile dysfunction have been papaverine hydrochloride, a smooth muscle relaxant, phentolamine mesylate, an &agr;-adrenergic blocker, and several other drugs which are used because of their ability to cause vasodilation. Recent data have suggested that prostaglandin E
1
either alone or in combination with papaverine produces an improved erectile response. The use of these drugs often requires special applicators, which besides being cumbersome, are also painful to use. However, the use of topical gels, creams and ointments for treating impotency has been proposed in several publications.
U.S. Pat. No. 5,583,144 discloses compositions for relieving erectile impotence in men which contain piperoxan in a pharmaceutically acceptable carrier. As the pharmaceutically acceptable carrier, commercially available gels, ointment and creams, such as the hydrogel, hydroxypropylmethylcellulose are optionally used. The patent does not address the importance of the rate of delivery to the site of action.
U.S. Pat. No. 5,256,652 discloses a topical composition which enhances the maintenance of penis erection and which contains a peripheral vasodilator, an absorption enhancer and, optionally, a vasocontrictor and an alpha receptor combined with a pharmacologically acceptable topical vehicle. The patent discloses that “[t]he problem with topically administered drugs is their limited penetration of the drug through the skin” and
Drizen Alan
Nath Gary M.
Rothbart Peter
L.A.M. Pharmaceutical Corporation
Nath Gary M.
Nath & Associates PLLC
Nguyen Helen
Webman Edward J.
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