Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Web – sheet or filament bases; compositions of bandages; or...
Reexamination Certificate
2000-12-14
2003-05-13
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Web, sheet or filament bases; compositions of bandages; or...
C424S443000, C424S445000, C424S447000, C424S448000, C514S946000, C514S947000, C514S944000
Reexamination Certificate
active
06562370
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to transdermal administration of pharmacologically active agents, and more particularly relates to methods and compositions for transdermally administering steroid drugs, particularly progestins and estrogens.
BACKGROUND
The delivery of drugs through the skin provides many advantages; primarily, such a means of delivery is a comfortable, convenient and noninvasive way of administering drugs. The variable rates of absorption and metabolism encountered in oral treatment are avoided, and other inherent inconveniences—e.g., gastrointestinal irritation and the like—are eliminated as well. Transdermal drug delivery also makes possible a high degree of control over blood concentrations of any particular drug.
Skin is a structurally complex, relatively thick membrane. Molecules moving from the environment into and through intact skin must first penetrate the stratum corneum and any material on its surface. They must then penetrate the viable epidermis, the papillary dermis, and the capillary walls into the blood stream or lymph channels. To be so absorbed, molecules must overcome a different resistance to penetration in each type of tissue. Transport across the skin membrane is thus a complex phenomenon. However, it is the cells of the stratum corneum which present the primary barrier to absorption of topical compositions or transdermally administered drugs. The stratum corneum is a thin layer of dense, highly keratinized cells approximately 10-15 microns thick over most of the body. It is believed to be the high degree of keratinization within these cells as well as their dense packing which creates in most cases a substantially impermeable barrier to drug penetration. With many drugs, the rate of permeation through the skin is extremely low and is particularly problematic for high molecular weight drugs such as steroids. Consequently, a means for enhancing the permeability of the skin is desired to effect transport of a steroid drug into and through intact skin.
In order to increase the rate at which a drug penetrates through the skin, then, various approaches have been followed, each of which involves the use of either a chemical penetration enhancer or a physical penetration enhancer. Physical enhancement of skin permeation include, for example, electrophoretic techniques such as iontophoresis. The use of ultrasound (or “phonophoresis”) as a physical penetration enhancer has also been researched. Chemical enhancers are compounds that are administered along with the drug (or in some cases the skin may be pretreated with a chemical enhancer) in order to increase the permeability of the stratum corneum, and thereby provide for enhanced penetration of the drug through the skin. Ideally, such chemical penetration enhancers (or “permeation enhancers,” as the compounds are referred to herein) are compounds that are innocuous and serve merely to facilitate diffusion of the drug through the stratum corneum.
Various compounds for enhancing the permeability of skin are known in the art and described in the pertinent texts and literature. Compounds that have been used to enhance skin permeability include: sulfoxides such as dimethylsulfoxide (DMSO) and decylmethylsulfoxide (C
10
MSO); ethers such as diethylene glycol monoethyl ether (available commercially as Transcutol®) and diethylene glycol monomethyl ether; surfactants such as sodium laurate, sodium lauryl sulfate, cetyltrimethylammonium bromide, benzalkonium chloride, Poloxamer (231, 182, 184), Tween (20, 40, 60, 80) and lecithin (U.S. Pat. No. 4,783,450); the 1-substituted azacycloheptan-2-ones, particularly 1-n-dodecylcyclazacycloheptan-2-one (available under the trademark Azone® from Nelson Research & Development Co., Irvine, Calif.; see U.S. Pat. Nos. 3,989,816, 4,316,893, 4,405,616 and 4,557,934); alcohols such as ethanol, propanol, octanol, benzyl alcohol, and the like; fatty acids such as lauric acid, oleic acid and valeric acid; fatty acid esters such as isopropyl myristate, isopropyl palmitate, methylpropionate, and ethyl oleate; polyols and esters thereof such as propylene glycol, ethylene glycol, glycerol, butanediol, polyethylene glycol, and polyethylene glycol monolaurate (PEGML; see, e.g., U.S. Pat. No. 4,568,343); amides and other nitrogenous compounds such as urea, dimethylacetamide (DMA), dimethylformamide (DMF), 2-pyrrolidone, 1-methyl-2-pyrrolidone, ethanolamine, diethanolamine and triethanolamine; terpenes; alkanones; organic acids, particularly salicylic acid and salicylates, citric acid and succinic acid; and certain peptides, e.g., peptides having Pro-Leu at the N-terminus and followed by a protective group (see U.S. Pat. No. 5,534,496).
Percutaneous Penetration Enhancers,
eds. Smith et al. (CRC Press, 1995) provides an excellent overview of the field and further background information on a number of chemical and physical enhancers.
Although many chemical permeation enhancers are known, there is an ongoing need for enhancers that are highly effective in increasing the rate at which a drug permeates the skin, do not result in skin damage, irritation, sensitization, or the like, and can be used to effect transdermal delivery of even high molecular weight drugs such as steroid drugs. It has now been discovered that hydroxide-releasing agents are highly effective permeation enhancers, even when used without coenhancers, and provide all of the aforementioned advantages relative to known permeation enhancers. Furthermore, in contrast to conventional enhancers, transdermal administration of drugs with hydroxide-releasing agents as permeation enhancers, employed at the appropriate levels, does not result in systemic toxicity.
Estrogen therapy is commonly used in the pharmacological treatment of altered hormone profiles or sexual dysfunction in women. Estrogen-based therapies are generally used to increase mucous production, provide vasodilator effects, and/or to increase the general health of the vagina. Nadelson et al., eds.,
Treatment Interventions in Human Sexuality
(New York: Plenum Press, 1983). In such treatments, estrogen is administered orally, parenterally (e.g., by injection), or topically. With oral administration, as is true with the oral administration of many steroid hormones, estrogens tend to be inactivated; estradiol, for example, is converted to estriol and estrone and then conjugated to glucuronic acid or sulfate. Additionally, estrogens also impair hepatic secretory activity. This “first pass” effect may lead to an undesirable increase in the production of certain coagulation factors and other biologically important compounds by the liver. Parenterally administered estrogen avoids the aforementioned problems associated with oral administration, but as an invasive mode of administration is generally undesirable.
Accordingly, there is a need in the art for an effective method for administering estrogenic agents in a manner that does not involve oral, parenteral or topical drug administration.
SUMMARY OF THE INVENTION
It is thus a primary object of the invention to address the above-described need in the art by providing a method for transdermally administering a steroid drug, particularly progestins and/or estrogens.
It is another object of the invention to provide such a method wherein a hydroxide-releasing agent is employed as a permeation enhancer to increase the flux of the steroid drug through a patient's skin or mucosal tissue.
It is still another object of the invention to provide such a method wherein the amount of hydroxide-releasing agent employed is optimized to enhance permeation while minimizing or eliminating the possibility of skin damage, irritation or sensitization.
It is an additional object of the invention to provide formulations and drug delivery systems for carrying out the aforementioned methods.
Additional objects, advantages and novel features of the invention will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be
Hsu Tsung-Min
Luo Eric C.
Dermatrends, Inc.
Eberle Shelley P.
Ghali Isis
Reed Dianne E.
Reed & Eberle LLP
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