Inactivation of amikacin and gentamicin by carbenicillin in patients with end-stage renal failure.

Aminoglycosides are inactivated by carbenicillin in vitro and in patients with end-stage renal failure. In vitro, amikacin is inactivated to a lesser extent than is gentamicin. In five patients on chronic hemodialysis, serum levels of amikacin alone and after repeated intravenous carbenicillin infusions were determined. Analogous gentamicin studies were conducted with five different patients. Neither amikacin serum levels nor serum clearances were affected by carbenicillin. The mean gentamicin serum half-life was significantly lower in the presence of carbenicillin: 18.4 +/- 8.2 compared with 61.6 +/- 30.7 h. Serum clearance increased significantly. The inactivation of gentamicin by carbenicillin was both time related (greater than 12 h of exposure) and concentration dependent (molar carbenicillin/gentamicin ratios greater than or equal to 39:1). Amikacin would be preferable to gentamicin in patients with end-stage renal failure.