Enhancement of solubility and dissolution rate of baicalein, wogonin and oroxylin A extracted from Radix scutellariae.

Baicalein, wogonin, and oroxylin A are three major hydrophobic components in the extract of Radix scutellariae with wide spectrum of pharmacological applications. The purpose of this study was to enhance the solubility, dissolution rate and stability of baicalein, wogonin and oroxylin A by solid dispersion (SD) technique. SD of the extract with various polymers was prepared to select the best carrier. Solubility study, chemical stability study and dissolution study were performed to characterize the SD. The solubility of all three components, after forming solid dispersion with povidone K-30 (PVP K-30) was significantly increased in pH 6.8 medium at room temperature. Stability study conducted for 80days elucidated that the SD in powder state was fairly stable without the aid of Vitamin C (VC). VC was required as antioxidant to impart stability to baicalein in aqueous medium. The dissolution test of the SD of three components, admixed with VC at the weight ratio of 1:6 (Radix scutellariae extract: VC, w/w) exhibited faster dissolution rate with 100% release of all components. Pharmacokinetic study of baicalein solid dispersion revealed that AUC and Cmax significantly increased by solid dispersion preparation. Thus, the current developed method, being simple, economical and effective, can be useful for the production of soluble dosage forms of the extract of Radix scutellariae in commercial scale.