A study of the adhesive-skin interface: correlation between adhesion and passage of a drug

The phenomena taking place at the patch-skin interface, in particular the a dhesion of a pressure sensitive adhesive (PSA) film loaded with drug and th e partition of the drug between the parch and the skin were correlated. The kinetics of adhesion as well as those of drug passage were studied in deta il. Adhesion data were collected from peel test either on skill or on a pol ymer model. Passage of the drug was studied in a simple system composed of PSA film stuck on skin. In some experiments the film was left on the skin t hroughout the experiment; in others, it was periodically removed and stuck on again to keep the adhesion force constant during the whole of the experi ment. We observed a rapid increase of the drug content in the skin until a plateau was reached. One adhesion for the whole experiment or several adhes ions gave a similar curve. The main difference was the rate of increase of skin drug content and the value of the plateau. Different hypotheses concer ning the relationship between the adhesion of this PSA and changes in the f lux of drug have been put forward. However, it is difficult to extrapolate from this model to the in vivo situation because of variation both between individuals and with time. (C) 2000 Elsevier Science B.V. All rights reserv ed.