Impregnation of tranilast to the poly(lactic acid) fiber with supercritical carbon dioxide and the release behavior of tranilast

Abstract

The impregnation of hydrophobic drug, tranilast, to the poly(lactic acid) (PLA) fiber with supercritical carbon dioxide (scCO2) and the release behavior of tranilast from the PLA fiber were studied. The adsorption behavior of tranilast to the PLA fiber was evaluated. Equilibrium adsorption of tranilast was obtained in 60 min. The amount of adsorbed tranilast in equilibrium was 0.3-0.5% on the weight of fiber. The apparent diffusion coefficient was estimated from the apparent adsorption curve. The order of this value was 10-12 m2/s. The tensile strength and modulus of the PLA fiber treated with scCO2/ EtOH decreased, as compared to the untreated fiber. By the scanning microspectrophotometric measurements, it was confirmed that tranilast was distributed uniformly in the PLA fiber. It was revealed that the tranilast was not crystallized in the PLA fiber. A fairly slow release of tranilast from the PLA fiber was observed in buffer solution. The amount of released tranilast after 60 days was about 20% of the total drug amount introduced into the body of a rat.