Efavirenz oral delivery via lipid nanocapsules: formulation, optimisation, and ex-vivo gut permeation study

Present investigation aimed to prepare, optimise, and characterise lipid nanocapsules (LNCs) for improving the solubility and bioavailability of efavirenz (EFV). EFV-loaded LNCs were prepared by the phase-inversion temperature method and the influence of various formulation variables was assessed using Box-Behnken design. The prepared formulations were characterised for particle size, polydispersity index (PdI), zeta potential, encapsulation efficiency (EE), and release efficiency (RE). The biocompatibility of optimised formulation on Caco-2 cells was determined using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay. Then, it was subjected to ex-vivo permeation using rat intestine. EFV-loaded LNCs were found to be spherical shape in the range of 20-100 nm with EE of 82-97%. The best results obtained from LNCs prepared by 17.5% labrafac and 10% solutol HS15 when the volume ratio of the diluting aqueous phase to the initial emulsion was 3.5. The mean particle size, zeta potential, PdI, EE, drug loading%, and RE during 144 h of optimised formulation were confirmed to 60.71 nm, -35.93 mV, 0.09, 92.60, 7.39 and 55.96%, respectively. Optimised LNCs increased the ex vivo intestinal permeation of EFV when compared with drug suspension. Thus, LNCs could be promising for improved oral delivery of EFV.