Pharmacokinetics and safety of a unilamellar liposomal formulation of amphotericin B (AmBisome) in rabbits.
A unilamellar liposomal formulation of amphotericin B (LAmB) known as AmBisome was safely administered intravenously to 20 rabbits at 0.5, 1.0, 2.5, 5, or 10 mg/kg of body weight, whereas of 12 rabbits given desoxycholate amphotericin B (DAmB) intravenously at 0.5, 1.0, or 1.5 mg/kg, 2 died of acute cardiac toxicity when DAmB was administered at the highest dose. Single-dose LAmB (1 mg/kg) achieved a maximum concentration in serum (Cmax) of 26 +/- 2.4 micrograms/ml and an area under the curve to infinity (AUC0-infinity) of 60 +/- 16 micrograms.h/ml, while single-dose DAmB (1.0 mg/kg), by comparison, achieved a lower Cmax (4.7 +/- 0.2 micrograms/ml; P = 0.001) and a lower AUC0-infinity (30.6 +/- 2.2 micrograms.h/ml; P = 0.07). Following administration of a single dose of LAmB (10 mg/kg), a disproportionately higher Cmax (287 +/- 14 micrograms/ml) and AUC0-infinity (2,223 +/- 246 micrograms.h/ml) occurred, indicating saturable elimination. After chronic dosing (n = 4) with LAmB at 5.0 mg/kg/day for 28 days or DAmB at 1.0 mg/kg/day for 28 days, LAmB achieved daily peak levels of 122.8 +/- 5.8 micrograms/ml and trough levels of 34.9 +/- 1.8 micrograms/ml, while DAmB reached a peak of only 1.76 +/- 0.11 microgram/ml and a trough of 0.46 +/- 0.04 microgram/ml (P < or = 0.001). Significant accumulations of amphotericin B into reticuloendothelial organs were observed, with 239 +/- 39 micrograms/g found in the liver after chronic LAmB dosing (5 mg/kg/day), which was seven times higher than the 33 +/- 6 micrograms/g after DAmB dosing (1 mg/kg/day) (P = 0.002). Accumulation in kidneys, however, remained 14-fold lower (P =0.04) following LAmB dosing (0.87 +/- 0.61 microgram/g) than after DAmB dosing (12.7 +/- 4.6 microgram/g). Nephrotoxicity occurred in only one of four LAmB treated animals, while it occurred in all four chronically DAmB-treated animals: mild hepatozicity with transaminase elevations was seen in one LAmB-treated rabbit. We conclude that LAmB safely achieved higher Cmax(s) and AUC0-infinity(s) and demonstrated saturable, nonlinear elimination from plasma via reticuloendothelial organ uptake. Take reduced nephrotoxicity of LAmB correlated with diminished levels of amphotericin B in the kidneys.
Infectious Diseases Section, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
J W
JW
Lee
M A
MA
Amantea
P A
PA
Francis
E E
EE
Navarro
J
J
Bacher
P A
PA
Pizzo
T J
TJ
Walsh
D000666:Amphotericin B / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000633:toxicity; D000818:Animals; D000935:Antifungal Agents / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000633:toxicity; D002851:Chromatography, High Pressure Liquid; D003840:Deoxycholic Acid / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000633:toxicity; D004337:Drug Carriers; D004338:Drug Combinations; D005260:Female; D007674:Kidney Diseases / Q000139:chemically induced; D008081:Liposomes; D011817:Rabbits; D013056:Spectrophotometry, Ultraviolet; D014018:Tissue Distribution
D000935:Antifungal Agents; D004337:Drug Carriers; D004338:Drug Combinations; D008081:Liposomes; C068538:liposomal amphotericin B; D003840:Deoxycholic Acid; D000666:Amphotericin B; C059765:amphotericin B, deoxycholate drug combination