The pharmacokinetics, tissue distribution, and toxicity of free amphotericin B (free AmB) or amphotericin B encapsulated in liposomes (L-AmB) were characterized in experimental diabetic rats and compared with data obtained from nondiabetic rats. After 7 days of insulin-controlled diabetes or saline, each rat was administered a single intravenous bolus dose of free AmB or L-AmB (0.8 mg/kg body weight). Blood samples were obtained before administration and serially thereafter for the assessment of serum pharmacokinetics, nephrotoxicity, and biochemical parameters. Before drug treatment, diabetic rats demonstrated marked increases in serum cholesterol and triglyceride levels compared with levels in nondiabetic rats. A significant increase in serum creatinine levels was observed in nondiabetic rats given free AmB but not in other groups. Whereas AmB pharmacokinetics were significantly altered in diabetic rats administered free AmB, no kinetic differences were found between groups given L-AmB. Renal AmB levels were markedly increased in nondiabetic rats given free AmB compared with those in all other groups. Furthermore, significantly greater concentrations of free AmB were found in lung tissue of rats administered L-AmB independent of disease state. Hepatic levels of AmB were reduced in diabetic rats administered free AmB. The disposition and nephrotoxicity of L-AmB were independent of vascular lipid composition.

The beneficial effects of post-insult administration of pentoxifylline, a novel hemorheologic agent experimentally studied in various ischemic diseases, were evaluated in two models of acute renal failure (ARF): direct nephrotoxicity (mercuric chloride 4 mg/kg via femoral vein) and hemoglobinuria (glycerol 10 ml/kg i.m.). Glomerular filtration rate (GFR) was estimated at baseline and following drug administration by creatinine clearances; tubular function was assessed by renal fractional and absolute electrolyte excretions. The incidence of mortality was decreased with a single dose of pentoxifylline 45 mg/kg (21.4%) compared to control rats (71.4%) 48 hours following induction of ARF with mercuric chloride. Although GFR and renal electrolyte excretion were significantly greater in rats given pentoxifylline compared to saline, the magnitude of difference was minimal. A return to baseline GFR was observed in the glycerol group administered a single i.p. dose of pentoxifylline 45 mg/kg (100.8 +/- 54.8%) compared to saline controls (45.6 +/- 22.7%; P less than 0.05). No differences in renal electrolyte excretion or mortality were observed in this model. Taken together, these data suggest that pentoxifylline, administered shortly after the initiation of ARF, exerts an ameliorative effect on the course and mortality of experimental ARF. The mechanism of amelioration most likely involves the stimulation of renal vasodilator prostaglandins as well as prevention of vascular congestion.