Adefovir dipivoxil loaded proliposomal powders with improved hepatoprotective activity: formulation, optimization, pharmacokinetic, and biodistribution studies

The present study aimed to prepare proliposomal formulae for improving the oral bioavailability of adefovir dipivoxil (AD), a nucleoside reverse transcriptase inhibitor effective against hepatitis B virus (HBV). The prepared proliposomal formulae were characterized for entrapment efficiency (E.E.%), vesicle size and in vitro drug release after reconstitution to conventional liposomes. The optimized formula (F9) with a maximum desirability value of 0.858 was selected having E.E.% of 71 +/- 3.3% with an average vesicle size of 164.6 +/- 5nm. Moreover, the crystallization of AD within the optimized formula investigated via powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC) confirmed the presence of the drug in an amorphous state within the lipid vesicles with enhanced stability over a storage period of 12months. Thioacetamide-induced liver damage in rats evidenced by elevated liver enzymes was significantly improved after treatment with the optimum formula. Pharmacokinetic and biodistribution studies of formula F9 showed a higher accumulation of AD in the liver with enhanced bioavailability compared to AD suspension which highlights its potential advantage for an effective treatment of chronic HBV. Hence, proliposomal drug delivery is considered as a better choice for the oral delivery of AD.