Safety evaluation of ABELCET, an amphotericin B lipid complex (ABLC): toxicity studies in rats

ABELCET (ABLC) is a widely used amphotericin B lipid complex formulation that is approved for use in the treatment of invasive fungal infections in patients who are refractory or intolerant of conventional amphotericin B (AmB). The safety profile of ABLC has been characterized in two acute and two repeat-dose toxicity studies in rats. The acute toxicity studies indicated that single intravenous doses of ABLC are at least 20 times less toxic than conventional amphotericin B doses without the lipid formulation, Fungizone. Intravenous doses of 0, 1, 3, or 10 mg/kg/day to groups of rats (10 to 15 rats/sex/group) for 31 days elicited no mortality or overt clinical signs of toxicity, whereas alternate intravenous/intraperitoneal doses (three each per week) for 6 months, produced one death in the control group, one in the intermediate-dose group, and two in the high-dose group. Clinical signs (predominantly piloerection and hunched posture at 10 mg/kg/day) were attributed to granulomatous inflammatory lesions in the abdominal wall, mesentery, and omentum, which were produced by the intraperitoneal injections of ABLC. Feed consumption and body weight gains decreased in high-dose male rats in the one-month study and were significantly lower in male rats at 3 and 10 mg/kg/day in the 6-month study. In contrast, water consumption increased in male and female rats in both studies. Trends of minimal to moderate, dose-related increases in relative kidney, liver and spleen weights, and histological evidence of hypertrophy and hyperplasia of reticuloendothelial cells in the liver and spleen and mild, dose-related impairment of renal function occurred in both the 1- and 6-month studies. Examination of high-dose rats following a recovery period of 28 days after completion of 31 days of dosing suggested that treatment-related changes were reversible. The observed changes for ABLC are similar to those for other amphotericin B lipid formulations, such as AmBisome (LAmB), except for the hepatoxicity, which was observed for LAmB, but not for ABLC.