Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0042109 (urticaria)
 6,569 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This comprehensive review of transdermal delivery systems for estrogens and progestins covers skin structure and absorption of chemical agents by diffusion and partition, permeability and use of enhancers to speed absorption, choices of drugs for transdermal contraceptives, animal and clinical work with estradiol, ethinyl estradiol and levonorgestrel, use of pro-drugs and derivatives, types of transderm delivery systems, metabolism of these drugs by skin and skin flora, and cutaneous side effects, all illustrated graphically and mathematically. Drug absorption entails diffusion through the primarily and mathematically. Drug absorption entails diffusion through the primarily lipophilic stratum corneum, and the hydrophilic epidermis: transport between these layers is often the rate-limiting step. For many drugs, permeability enhancers such as dimethyl sulfoxide, ethanol and ethyl acetate are needed. Good drug candidates for transdermal application must be potent in low doses, have short half-lives, not elicit an allergic response nor be extensively metabolized in skin. The permeability of levonorgestrel has been increased by using esters, and "pro-drugs" which are compounds that increase polarity, but are degraded to the active drug by skin tissue. The estrogens are subject to a minor degree of oxidation, and no significant degradation by skin microbes. There are 3 types of transdermal systems: the membrane, matrix and drug reservoir types. The Estraderm brand system for estradiol is a membrane-moderated design with ethanol as the chemical enhancer. Skin penetration is the rate-limiting step. Levonorgestrel as been tested with ethyl acetate and ethanol as penetration enhancers in rats, rabbits, and in a Phase I trial. The development of a transderm system for a combination of estrogen and progestin is a complex problem because 2 different enhancers must be used. Most transdermal systems are mild skin irritants, but incidence of contact allergy or urticaria are rare, with no cases yet reported from use of Estraderm. Transdermal application of contraceptive steroids is expected to be available eventually.
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PMID:Transdermal delivery of contraceptives. 227 99