Pharmacokinetic profile of a new matrix-type transdermal delivery system: diclofenac diethyl ammonium patch

A transdermal delivery system containing the anti-inflammatory analgesic diclofenac diethyl ammonium in an ethyl hexyl acrylate and vinyl acetate pressure-sensitive adhesive system was developed for percutaneous absorption. These patches were subjected to in vitro permeation and permeation enhancement studies through rat skin using a specially designed diffusion cell. Further, the work deals with percutaneous absorption studies carried out on both animals and human volunteers. The pharmacokinetic parameters calculated from the blood levels of the drug reveal a profile typical of a sustained-release formulation, with the ability to maintain adequate plasma levels for 24 hr (i.e., up to the next application). (Area under the curve [AUC]: 4.356 +/- 1.3 mcg/ml.hr in animals and 0.442 +/- 0.053 mcg/ml.hr in humans; Tmax was 8 hr in both the cases, whereas Cmax was 0.288 +/- 0.088 mcg/ml in animals and 0.034 +/- .008 mcg/ml in human volunteers.) The amount of the drug bioavailable for targeting the sites of action is lower than via the oral route, but the absorbed dose appears to be adequate for therapeutic use, particularly because of the absence of side effects.