Effects of conductive polyazulene and plasticizer embedded in deproteinized natural rubber transdermal patch on electrically controlled naproxen release-permeation.

Naproxen (Npx) was utilized as an anionic drug and loaded in the deproteinized natural rubber (DPNR) films prepared by the UV irradiation. The in-vitro drug release-permeation from the DPNR films and through the pig skin was investigated under the effects of the plasticizer type and amount, silicone oil (Si) and dibutyl phthalate (DBP), applied electric potential, and used conductive polyazulene as the drug encapsulation host. The drug release-permeation consisted of 2 successive periods: the pore formation period and release-permeation period. In the first period, the scaling exponent n1 values were between 0.5 and 1 indicating the decreasing drug rate with time. In the second stage, the scaling exponent n2 values were higher than 1 indicating the increasing drug rate with time. The Npx release-permeation amount increased with increasing amount of hydrophilic plasticizers. The efficiency of plasticizers on the Npx release-permeation amount was ranked as follows: DBP > Si. The Npx release-permeation amount was drastically enhanced from the applied electrical potential due to the electro-repulsive force between the negatively charged drug and the negatively charged electrode, and the presence of the Npx-doped conductive polyazulene. Other characteristics were also investigated in details namely the matrix morphology, and the pore formation during the two periods.