Changes in renal handling of platinum in cisplatinum-treated rats following induction of metabolic acidosis or alkalosis.

Manipulations of metabolic acid-base status were used in an attempt to modify the renal handling and toxicity of the anticancer drug cisplatinum. Rats were orally pretreated with either tap water (TW), ammonium chloride (AC), or sodium bicarbonate (SB) for 3 days prior to intraperitoneal administration of a high cisplatinum dose (7.5 mg/kg b.w.). Urine was collected daily for 4 days between drug dosing and killing of the animals. AC-pretreated rats did not exhibit the characteristic cisplatinum-induced diuresis and were unable to maintain an acid urinary pH following drug administration. AC rats had a significantly lower, and SB rats a significantly higher, urinary excretion of platinum than did TW rats. Platinum excretion was found to be correlated with urinary pH (r = 0.88) and not urinary volume (r = 0.30). The renal concentration of platinum was greater in AC animals than in SB or TW animals, but no significant difference was observed in liver or plasma concentrations between the groups. Both pretreated groups had equal percent of free vs bound platinum. Proteinuria was more severe in AC-pretreated rats, but histologic evidence of renal tubular damage was present in all the three groups. It is concluded that metabolic acidosis can seriously impair the renal handling of high dose cisplatinum but that metabolic alkalosis offers no evident advantages over nonpretreatment.