RETRACTED ARTICLE: Enhanced dissolution and oral bioavailability of poorly water-soluble herb (Kaempferia parviflora) extract using solid dispersions: effect of surfactants and concentrations

Abstract

Kaempferia parviflora (KP) is a Thai traditional herb. The primary pharmacologically active substances are methoxyflavones, namely, 5,7-dimethoxyflavone, 5,7,4′-trimethoxyflavone, and 3,5,7,3′,4′-pentamethoxyflavone. These methoxyflavones are poorly soluble in water and thus have low oral absorption. In previous research, dichloromethane-extracted KP (KPD) and Kollicoat® IR (PVA-co-PEG) at a 1:1 ratio were dissolved in dichloromethane and used to produce a solid dispersion (KPD/PVA-co-PEG). In this study, the effects of surface-active agents in the solid dispersion system on dissolution and bioavailability were investigated, employing a series of concentrations (1%, 3%, and 6% w/w) of various surfactants (polysorbate 20, polysorbate 60, polysorbate 65, sorbitan ester 20, sorbitan ester 40, and sorbitan ester 80). The highest dissolution profiles were found (approximately 100% dissolution) when using polysorbate 20 at a concentration of 6% w/w (PS20-6) and these corroborated with the results from the surface free energy determination. The bioavailability of methoxyflavones was studied in Wistar rats: compared to KPD, AUC of KPD/PVA-co-PEG and PS20-6, they were 3.71- and 4.88-times higher, respectively. These results suggest that the solid dispersion-based KPD/PVA-co-PEG may be able to modify the dissolution profiles and oral absorption, and the surfactant-in-solid-dispersion system PS20-6 can be particularly effective.