Preparation of Ammonio-Terminated Polyoxyethylene/Polydimethylsiloxane Block Copolymer and Application to Transdermal Penetration Enhancer

Polyoxyethylene(PEO)/polydimethylsiloxane (PDMS) block copolymers bearing ammonium group at the one side chain end was prepared and the enhancing activity on the drug permeation through the skin was investigated in vitro. The enhancing mechanism was discussed by simulating the permeation profile with a Fickian diffusion equation. These copolymers efficiently promoted the transdermal drug permeation and the activity considerably depended on the degree of polymerization of PEO and PDMS. Concerning the role of each part in the molecule, the compound consisting of all moeities, namely PEG, PDMS and cationic group showed highest enhancing activity. From the result of calculation of partition and diffusion parameters, it was revealed that these compound increased only drug partition from vehicle to the skin. Moreover, this materials scarcely showed the skin irritation.