Development of drug-in-adhesive transdermal patch for α-asarone and in vivo pharmacokinetics and efficacy evaluation

A transdermal drug delivery system has been reported that can increase the bioavailability, reduce the administration duration, and maintain the concentration of drug in blood. In the present study, drug-in-adhesive transdermal patches of alpha-asarone using Eudragit E100 as pressure-sensitive adhesives and oleic acid plus isopropyl myristate as penetration co-enhancers were developed. In vitro permeation, in vivo pharmacokinetics in rabbits, and efficacy in asthmatic rats were evaluated. The results showed that co-enhancers could induce a synergistic effect on alpha-asarone permeability. In vivo study suggested that the patch can keep a relatively certain blood level of drug within 10-30 h in rabbits. Furthermore, the patch with the size of 4 cm(2) containing drug 3 mg/cm(2) showed a noticeable treating effect on asthmatic rats which is equivalent to the effect of dexamethasone, while avoiding the side-effect induced by the corticorsteroid. This suggests that the drug-in-adhesive transdermal patch is a promising delivery system containing alpha-asarone to be used for asthma treatment.