In situ liposomal preparation containing amphotericin B: related toxicity and tissue disposition studies

The purpose of this research was to develop a novel hydroalcoholic method for the preparation of liposome entrapping inclusion complex of amphotericin B (AmB) with a view to obtaining reduced toxicity and superior tissue distribution of AmB in vivo. The method involves initial preparation of AmB-hydroxypropyl-beta-cyclodextrin (AmB-HPBCD) intercalated proliposome which is subsequently converted into a liposome dispersion by single dilution method. The AmB-liposome (L-AmB) derived from proliposome exhibited a superior entrapment efficiency (94.8 +/- 0.7%) compared to liposomes prepared by employing a conventional solvent-based technique (89.7 +/- 2.9%). The dose that was lethal to 50% of subjects (LD50) (mg/kg) value of AmB contained in stabilized proliposome-based liposomes was 18.6 +/- 0.25, whereas that in conventional solvent-based liposomes was 7.8 +/- 0.25. Incorporation of AmB-HPBCD into hydroalcoholic liposomes enhanced antifungal activity in experimental aspergillosis in Balb/c mice in vivo: 80% survival was recorded after 7 days of therapy and the fungal load in lung was reduced. The results clearly demonstrate that preferential uptake of L-AmB entrapped inclusion complex (AmB-HPBCD) by the reticulo endothelial system correlated with diminished levels of AmB in infected (p > 0.05) and noninfected (p > 0.001) kidney after 24 hr compared to that observed with conventional solvent-based L-AmB. Therefore, proliposome-based liposome entrapping inclusion complex of AmB with HPBCD offered an improved therapeutic efficacy by lowering toxicity as well as by altering the tissue distribution pattern.