Ten children receiving pivampicillin for 8 days were studied. On the first 4 days the drug was given alone (4 x 500 mg/day), and on the last 4 days in combination with carnitine (4 x 1 g/day). Pivampicillin treatment was associated with formation and urinary excretion of pivaloylcarnitine and administration of carnitine aided the elimination of pivalate as its carnitine ester. The resting respiratory quotient increased from 0.86 +/- 0.01 to 0.96 +/- 0.01 on the 4th day of pivampicillin treatment. A shift was observed in the metabolic fuel consumption: a significant decrease was found in the amount of fats oxidized (0.31 +/- 0.17 vs 1.27 +/- 0.17 g x kg[-1] x 24 h[-1]). while the utilization of carbohydrates increased (6.20 +/- 0.51 vs 4.00 +/- 0.50 g kg[-1] x 24 h[-1]). Administration of carnitine decreased the respiratory quotient to 0.90 +/- 0.01 on the 8th day of treatment, consumption of fats increased, and the oxidation of carbohydrates decreased. The resting energy expenditure was not affected by the treatment.
Conclusion: Pivampicillin treatment results in inhibited oxidation of fats as metabolic fuel. This drug effect was partially reversed by carnitine which promotes the elimination of the pivaloyl moiety from the body.