Slow replenishment of carnitine deficiency after cessation of long-term treatment with pivaloyl-containing antibiotics.

Long-term treatment with pivampicillin and pivmecillinam for 6-24 months in five adults and one child reduced the total serum carnitine concentration to 3.7-14 mumol/l (reference value: 25-66 mumol/l). Muscle carnitine was reduced to 0.3-0.7 mumol/g wet weight (reference value: 3-5 mumol/g) in two cases. All patients had muscle symptoms with weakness, asthenia and pains. One showed signs of carnitine depletion in the liver with increased secretion of dicarboxylic acids (C6, C8, C10) in urine and limited ketone body formation during prolonged fasting. Serum carnitine increased slowly after cessation of therapy and reached normal concentrations after 6-12 months. All symptoms caused by carnitine depletion disappeared. This was achieved on a normal diet without carnitine supplementation.