Enhanced oral bioavailability of capsaicin in mixed polymeric micelles: Preparation, in vitro and in vivo evaluation

The aim of this study was to prepare capsaicin-loaded micelle for oral administration and pharmacokinetic studies in rats. The formulated capsaicin consisted of polyvinylpyrrolidone (PVP)/sodium cholate/phospholipid mixed micellar system. Spherical and physicochemical stable micelles were obtained with a particle size below 50 nm and zeta potential of less than −30 mV. The in vitro release of capsaicin from the micellar system in three different media (pH 7.4 phosphate buffer solution, pH 1.2 HCl solution and double distilled water) was significantly higher than that of free capsaicin. After oral administration, the formulated capsaicin exhibited a prolonged plasma circulation with the oral bioavailability increasing to 2.42-fold as compared with the free capsaicin. Additionally, a reduced irritation of capsaicin-loaded micelle on the gastric mucosa was observed. This novel micellar formulation significantly improved the oral bioavailability of capsaicin and brought a series of notable advantages for its oral delivery.