Apparent diffusion coefficient of sodium phenobarbitone in ethylcellulose microcapsules: effects of capsule size

Abstract

Ethylcellulose microcapsules of sodium phenobarbitone with a thick wall were prepared and fractionated. The apparent diffusion coefficient of sodium phenobarbitone was measured for the transport of the drug from the core of microcapsules into the surrounding sink condition. The apparent diffusion coefficient decreased with decreasing capsule size. Apart from structured water in and around the capsule wall, the volume fraction of pores in the membrane has been suggested as the source of the observed trend.