Amphotericin selectively increases peritoneal ultrafiltration

Because amphotericin B is known to affect transport rates across biologic membranes, the effects of this agent on transport parameters in an animal model of peritoneal dialysis were investigated. When amphotericin B in doses ranging from 0.5 to 25 mg/kg was instilled intraperitoneally with commercial dialysis solution, diffusive clearances of phosphate and urea did not differ from control values measured in the same animals, and only a modest increase in potassium clearance was detected. Ultrafiltration due to the osmotic gradient induced by the dextrose content of the dialysis solution increased significantly to 0.31 mL/kg/min with amphotericin B, compared with control values of 0.18 mL/kg/min. The drug did not affect dextrose transport and the osmotic gradient did not differ in the two groups. Hence, the ultrafiltration coefficient was higher with amphotericin B (14 microL/kg/min/mosm), than during control dialyses (6 microL/kg/min/mosm). Increased water flux was detected at the lowest dose and there was no dose relationship over the range studied. Amphotericin B may be the type of agent that will be clinically useful in patients with reduced peritoneal ultrafiltration capacity, and safer analogues should be explored.