Therapeutic and hemolytic evaluation of in-situ liposomal preparation containing amphotericin - beta complexed with different chemically modified beta - cyclodextrins.

PURPOSE: The objective of this study was to evaluate therapeutic and haemolytic effects of liposomal preparation derived from proliposome entrapping inclusion complex of amphotericin B (AmB) with the chemically modified beta-cyclodextrin (beta-CD). METHODS: a series of liposomal AmB formulations with varying beta-CD i.e. Hydroxy propyl beta-CD (HPBCD) and Sulfo butyl ether beta-CD (SBEBCD) having similar AmB content (0.5 mg/kg) were prepared and their effect compared with conventional liposomal amphotericin B (L-AmB) and free AmB on erythrocyte lysis and antifungals activity in experimental aspergillosis- and Cryptococcosis- mice model in-vivo. RESULTS: the liposomal AmB - HPBCD and AmB - SBEBCD found to be 6 times less toxic than free AmB or conventional liposomal AmB. Experimental findings indicate that infected animals treated with L-AmB entrapped inclusion complexes significantly reduced CFU values (fungal counts), whereas infected animals treated with conventional liposome or free AmB showed insignificant reduction in CFU. A marked increase in the percent survival was observed in the case of animals treated with liposomal AmB formulation (HPBCD/SBEBCD). Furthermore, the in-vitro toxicity (haemolysis) of the proliposome-based liposomal vesicles (PBLV) entrapped AmB-SBEBCD/HPBCD at 37 degrees C was approx. 50% at maximum of the conventional liposomal AmB at a dose of 118 microg/ml as measured after 1 hr. incubation. CONCLUSIONS: the results of these experiments permitted us to conclude that the stabilization of liposome derived from proliposome entrapping inclusion complex of amphotericin B (AmB) with beta-CD could serve an alternative approach to enhance the therapeutic window of AmB in clinical medicine.

PHARMACOKINETIC STUDIES OF IN-SITU LIPOSOMAL PREPARATION CONTAINING AMPHOTERICIN B COMPLEXED WITH DIFFERENT CHEMICALLY MODIFIED beta-CYCLODEXTRINS.

The purpose of this study was to evaluate the influence of chemically modified beta-cyclodextrin (beta-CD) which could affect the in-vivo stabilization of liposomal preparation derived from proliposome entrapping inclusion complex of amphotericin B (AmB) with beta-CD. A series of liposomal AmB formulations with varying beta-CD i.e. Hydroxypropyl beta-CD (HPBCD) & Sulfo butyl ether beta-CD (SBEBCD) and lipid dose having similar AmB content (0.5 mg/kg) were compared with conventional liposomal amphotericin B (L-AmB) or free AmB in rats and their pharmacokinetic data were analyzed considering the varying volume of distribution with respect to the varying lipid concentration (65mg to 110mg) in blood. These results indicate that L-AmB entrapped inclusion complexes safely achieved higher Cmax (P < 0.05) & AUC (P < 0.02) and demonstrated saturable, nonlinear elimination from plasma via reticuloendothelial organ uptake at higher lipid level (>80mg) as compared with conventional L-AmB or free AmB. Furthermore in-vivo stabilization potential for liposomal preparation via AmB/ beta-Cyclodextrin inclusion complexes appeared to be in pattern of HPBCD < SBEBCD. It is concluded that the preparation of liposome derived from proliposome entrapping inclusion complex of amphotericinB (AmB) with beta-CD could serve an alternative approach to enhance the therapeutic window of AmB in clinical medicine.

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.

Preparation, relative toxicity and therapeutic efficacy in mice and rats of liposomal HA-1-92, a new oxohexaene polyene macrolide antibiotic.

HA-1-92, a new polyene oxohexaene macrolide antibiotic isolated from Streptomyces CDRIL-312, was incorporated into liposomes containing phosphotidyl choline and cholesterol. The liposomal incorporated HA-1-92 considerably decreased toxicity when compared with free HA-1-92 in mice. Liposomal HA-1-92 showed improved pharmacokinetic profiles in rats. When administered to aspergillosis- and cryptococcosis-infected Balb/c mice, liposomal HA-1-92 showed increased antifungal activity, compared with free HA-1-92, with improved survival rate and decreased colony-forming units in lung, liver, spleen and kidney. These results suggest that liposomal HA-1-92 is more effective than free HA-1-92 in controlling experimental aspergillosis and cryptococcosis in Ba1b/c mice.