Enhanced oral bioavailability of Tanshinone IIA using lipid nanocapsules: Formulation, in-vitro appraisal and pharmacokinetics

Tanshinone IIA (TSIIA) is a promising phytomedicine that has been extensively studied due to its numerous biological activities, especially as an anticancer drug. However, it suffers from poor oral bioavailability owing to low aqueous solubility, poor permeability and exposure to first-pass metabolism. This study endeavored to improve TSIIA oral bioavailability by encapsulation into lipid nanocapsules (LNCs) for the first time. A previously reported phase-inversion method was used to prepare Tanshinone II A loaded LNCs (TSIIA-LNCs) with slight modifications based on a constructed phase diagram. They were then in-vitro characterized and their oral pharmacokinetics were studied in rats. TSIIA-LNCs showed excellent colloidal properties (size; 70 nm, PDI < 0.2 and zeta-potential; -13.5 mV), a high percent entrapment efficiency (98%) and a good drug payload (2.6 mg/g). Furthermore, the in-vivo pharmacokinetic study revealed a significant enhancement in both the rate and extent of absorption of TSIIA-LNCs compared with TSIIA suspension with about 3.6-fold increase in AUC(0-inf) value (p <= 0.01). Additionally, a significant increase in both half-life and mean residence time was exhibited by TSIIA-LNCs (p <= 0.01), confirming their long circulating properties. Therefore, the elaborated LNCs could be addressed as a promising nanoplatform permitting higher TSIIA oral bioavailability.