Influence of chemical enhancer and loading dose on caffeine and Vitamin B5 skin permeation and adhesion properties of transdermal patches

Evaluated in this study were the effects of the two parameters, namely level of penetration enhancer and drug loading dose, on in vitro skin release of Caffeine and vitamin B5 and adhesion properties of drug in adhesive transdermal systems. In order to characterize in vitro drug release, a hydrodynamically Chien permeation system with rat abdominal skin was employed. Caffeine skin release rate followed Higuchi's model with different concentrations of chemical enhancer as well as drug loading doses in transdermal patches; however, vitamin B5 skin permeation rate as well followed Higuchi's model as it does zero order equation in different time intervals. Ethylene glycol acts as a chemical enhancer in those adhesives which are sensitive to pressure changes. Adhesion properties were reduced as the chemical enhancer concentration and loading dosage were increased. The formulation with the 85 %w/w (measured on the basis of dry adhesive weight) Ethylene-glycol demonstrated optimum drug skin release and adhesion properties.