Abstract
The release of a drug from a transdermal delivery system with a rate controlling chitosan membrane was analyzed in vitro and in vivo. Lidocaine hydrochloride, a local anesthetic, was used as the model drug. The in vitro permeability of various chitosan membranes for the drug was investigated using a Franz diffusion cell. Drug release was slower through chitosan membranes with a higher degree of deacetylation (% DD) and with a larger thickness. A transdermal chitosan patch was developed using a chitosan membrane for rate control and a chitosan hydrogel as a drug reservoir. The most prolonged release in vitro was obtained with a 95% DD chitosan rate controlling membrane. The transport mechanism was found to be non‐Fickian. The functionality of this transdermal patch was studied on the forearm of human volunteers by assessing the anesthetic effect. Patches with 70% and 95% DD membranes delayed the anesthetic effect, increasing the delay with increasing % DD. It was concluded that a combination of chitosan membrane and chitosan hydrogel is a good transparent system for controlled drug delivery and that the release kinetics in vitro at least for lidocaine have a predictive value for its anesthetic effect in vivo. The demonstration of a direct relationship between in vitro drug membrane permeability and its physiological effect might be considered as quite unique.