ABSTRACT
Crystallinity and P-glycoprotein (P-gp) mediated efflux of drugs with low aqueous solubility collaboratively contributes to erratic absorption resulting in low/variable bioavailability. Herein, the amorphous solid dispersions (SD) of lumefantrine (LUMF) containing piperine (PIP), a P-gp and CYP3A4 inhibitor, were formulated with Soluplus (Sol), Klucel (Klu) and Lutrol F68 (Lut), polymeric carriers, to improve solubility and bioavailability of LUMF following oral administration. The LUMF-PIP-SD prepared with Sol exhibited higher aqueous solubility of LUMF in concentration dependent manner and LUMF-PIP-Sol demonstrating maximum aqueous LUMF solubility were characterized by DSC, FTIR and XRD. The DSC thermogram and XRD diffractogram of LUMF-PIP-SD confirmed the loss of crystallinity of LUMF ensuing improved dissolution while possible interaction of LUMF with PIP and /or Sol was evident in FTIR spectrum. DSC and dissolution studies confirmed the stability for LUMF-PIP-Sol SD stored for 90 days under stressed conditions of humidity and temperature. An in situ single-pass intestinal perfusion study in rats indicated 2.2-fold increase in intestinal permeation of LUMF co-administered with PIP. Improved bioavailability of LUMF was evidenced by increased AUC0-∞ and Cmax for LUMF in SD compared to alone LUMF or LUMF with PIP. Peter's four-day suppressive test indicated improved antimalarial activity for LUMF-PIP-Sol SD. Overall, the data suggest that the SD of LUMF incorporated with P-gp inhibitor PIP, improves the bioavailability as well as antimalarial efficacy of LUMF.
