ABSTRACT
Transdermal therapeutic systems (TTS) provide an effective method to deliver
certain drugs through skin. Lipophilic drugs with relatively high potency and
high volume of distribution are promising candidates for transcutaneous
delivery. Currently, eight TTS are marketed (scopolamine, clonidine, nitro-
glycerin, nicotine, estradiol, estradiol/progesterone, and fentanyl) (Hogan and
Cottam, 1991). Transdermal delivery provides a constant, controlled amount
of drug, and eliminates the gastrointestinal and hepatic “first-pass” metabolism
experienced with oral medication. Other advantages include the avoidance of
high peak levels in achieving a steady state concentration and increased patient
compliance. Although beneficial, these devices have adverse effects. One major
limitation in transdermal delivery is allergic contact dermatitis. This delayed
hypersensitivity reaction may result from various components of the TTS,
namely the drug, its vehicle, or the adhesive used to secure the TTS to the skin
(Ademola and Maibach, 1997). Other skin-related side effects from transdermal
systems include irritant dermatitis, hypo-or hyperpigmentation, erythema,
pruritis and excoriation.
