Cefetamet pivoxil treatment causes loss of carnitine reserves that can be prevented by exogenous carnitine administration.

Two groups of pediatric patients receiving cefetamet pivoxil treatment (3 x 500 mg daily) for 7 days were studied. In the first group (Group A) the drug was administered alone; in the second group (Group B) the drug was given in combination with a molar excess of carnitine (3 x 1 g). Medication with cefetamet pivoxil alone was associated with a large urinary excretion of pivaloylcarnitine: Approximately 71% of the daily pivalate intake could be eliminated as carnitine ester in the urine. In this group, the plasma level and the urinary output of free carnitine decreased. By contrast, in Group B, the administration of molar excess of carnitine aided stochiometric elimination of pivalate as carnitine ester, and the plasma levels and carnitine-free urinary output were unchanged. The data show that medication of cefetamet pivoxil results in the formation of pivaloylcarnitine in children; the sustained loss of carnitine esters can ultimately lead to carnitine deficiency. Molar excess of exogenous carnitine aids in the elimination of pivalate derived from cefetamet pivoxil therapy and helps to maintain the carnitine reserves.