Transdermal therapy

Euture electrotransport therapeutic systems will differ substantially from those just described. They will draw on advances in microelectronics and transdermal system technology to provide transdermal therapy for compounds with low passive permeation rates, patterned or pulsed dmg deHvery,... 

Clearly the physicochemical properties of a drug are a decisive factor in its overall activity. Where possible, molecular structures should be optimized to obtain best clinical performance. Rarely does an oral drug have physicochemical features suitable for topical or transdermal therapy, and it can take a great deal of systematic research to identify where the best balance of activity and permeability lies. Experience with corticosteroids suggests that as much as a 100-fold improvement in clinical activity may be attainable through molecular design, for today s most potent topical corticosteroids are more active than hydrocortisone by a factor at least this large. 

Perioperative use Continue administration of clonidine to within 4 hours of surgery and resume as soon as possible thereafter. Carefully monitor blood pressure and institute appropriate measures to control it. If transdermal therapy is started during the perioperative period, note that therapeutic plasma levels are not achieved until 2 to 3 days after initial application. 

Intranasal estradiol gives results comparable to transdermal estradiol, but substantially higher doses are needed. In 300 postmenopausal women, 17-P-estradiol 300 micro-grams/day was as effective as two patches per week delivering 50 micrograms/day (220). Adverse events rates were similar but moderate, and severe mastalgia was significantly less frequent with intranasal estradiol (7.2%) than with the patch (15.5%) 66% of the patients chose to continue the intranasal therapy and 34% the transdermal therapy. 

Poor adhesion and skin irritation, with erythema and itching, are the principal drawbacks of transdermal therapy (225). Skin irritation can be overcome in some cases by changing the application site every day. In a direct comparison of transdermal patches, the duration, severity, and number of skin reactions depended on the individual formulation and excipients. 

Advances in transdermal delivery systems (TDSs) and the technology involved have been rapid because of the sophistication of polymer science, which now allows incorporation of polymeric additives in TDSs in adequate quantity. Drugs with which transdermal therapy was pioneered include scopolamine, nitroglycerine, iso-sorbide dinitrite, clonidine, estradiol, nicotine, and testosterone [74],... 

Williams et al. [26] have recommended that HRT should be considered ...in all women with chronic liver disease who are postmenopausal, have primary or secondary amenorrhoea, or have had oophorectomy . Transdermal therapy is preferred. Serum bilirubin and liver enzymes... 

NOVEL DELIVERY SYSTEMS IN DERMATOLOGICAL AND TRANSDERMAL THERAPY... 

Hopkins, K. Ararons, L. Rowland, M. Absorption and excretion of clonidine following application of catapres-TTS to different skin sites. In Low Dose Oral and Transdermal Therapy of Hypertension, Weber, M.A., Drayer, J.I.M., Kolloch, R., Eds. Steinkopff Verlag Darmstadt, Germany, 1985 134-137. 

The clearance of a drug from the epidermis is an important determinant of dermal absorption and can influence therapeutic activity in both dermatological and transdermal therapy. The steady-state ratio of the concentrations of drug in the epidermis (C ei) (jer l s) and in the applied vehicle (C y i ) maybe related (Roberts 1991) as ... 

Membrane-controlled Transdermal Drug Administration Drug administration through the intact skin, transdermal therapy, was realized at the end of the 20th century with the development of transdermal therapeutic systems [22, 59]. Various polymers are necessary for this. 

K. Mojsiewicz-Piehkowska, M. Jamrogiewicz, M. 2ebrowska, M. Sznitowska, and K. Centkowska, Technology of an adhesive sihcone film as drug carrier in transdermal therapy. I Analytical methods used for characterization and design of the universal elastomer layers,/. Pharm. Biomed. Anal, 56,131-138, 2011. 

---