Transdermal delivery of propranolol using mixed grades of Eudragit: design and in vitro and in vivo evaluation.

A matrix-dispersion-type transdermal drug delivery system of propranol was developed using different ratios of mixed polymeric grades of Eudragit. Formulations were evaluated for in vitro dissolution characteristics using a Cygnus' sandwich patch holder. Selected formulations followed zero-order release kinetics. In vivo evaluation was carried out on healthy human volunteers following a balanced incomplete block design (BIBD). In vitro dissolution rate constant k and pharmacokinetic parameters generated from plasma and urine were evaluated statistically. Statistically excellent correlation was found between percentages of drug absorbed from patch versus Cmax, AUC0-24, and AUC0-alpha. A highly significant difference was observed when Cmax and AUC0-alpha generated from plasma and urine data were compared, but when ke, t1/2e, ka, and t1/2a were compared, the difference was not significant. Urinary excretion data are suggested as a simpler alternative to blood-level data in studying the kinetics of absorption and deriving the absorption parameter.