The effect of oral activated charcoal on the systemic clearance of gentamicin in rabbits with acute renal failure.

The effect of oral administration of activated charcoal on total body clearance of gentamicin administered intravenously (2 mg kg-1) has been studied in normal rabbits and rabbits with induced renal failure. Gastric intubation of a single dose (10 g) of activated charcoal to normal rabbits produced a significant reduction in gentamicin serum concentrations compared to control. Significant differences between treated and control groups, compatible with enhancement of gentamicin elimination, were observed in the calculated pharmacokinetic parameters (Kel, t 1/2, CL and AUC). To examine whether renal failure could augment the effect of activated charcoal in enhancing the systemic clearance of gentamicin, uranyl nitrate was used (0.75 mg kg-1, i.v.) to induce acute renal failure in rabbits. The derived pharmacokinetic parameters of gentamicin during the control phase in these animals were consistent with severe renal failure. The administration of activated charcoal, 2.5 h following gentamicin injection, produced a steeper decline in gentamicin concentration-time profiles and significant changes in Kel, t 1/2 and CL. The Kel and CL values increased to about 200%, while the t 1/2 value decreased to about 50%. The apparent changes in the pharmacokinetic parameters induced by charcoal administration were more marked in rabbits with renal failure than in normal rabbits; however, induction of renal failure did not augment the charcoal-induced clearance of gentamicin quantitatively.