Evaluation of the efficacy and toxicity of amphotericin B incorporated in lipid nano-sphere (LNS).

To develop a low-dose therapeutic system for amphotericin B (AmB), the efficacy and toxicity of lipid nano-sphere (LNS) incorporating AmB (LNS-AmB) were evaluated and compared with those of Fungizone, the conventional dosage form of AmB with sodium deoxycholate. LNS-AmB and Fungizone showed nearly equal activity against fungal cells both in vitro and in vivo. In contrast to Fungizone, however, LNS-AmB did not cause significant hemolysis. In addition, the vomiting toxicity of Fungizone was largely avoided by the use of LNS-AmB in dogs, in spite of the higher plasma AmB concentrations achieved by LNS-AmB. Therefore, LNS-AmB may be selective for fungal cells over mammalian cells. In a study of its toxicity and toxicokinetics in a regimen of daily 2-h intravenous infusions for 14 consecutive days, LNS-AmB showed less toxicity to the kidney than did Fungizone in spite of the higher plasma AmB concentrations achieved. LNS-AmB, therefore, allows the treatment of systemic fungal infections at low doses without the severe nephrotoxicity of Fungizone. Size-exclusion chromatography provided evidence that, when LNS-AmB was administered to rats, AmB was retained in the LNS particles in the blood circulation, but that when Fungizone was administered, AmB was transferred to high-density lipoproteins (HDL). AmB retained in LNS particles seemed to be less toxic to the kidney than was AmB associated with HDL. Consequently, LNS-AmB has the potential to become a low-dose therapeutic system for AmB, minimizing most of the severe side effects of AmB by decreasing the total dose required.