Chloroacetaldehyde and thiodiglycolic acid. two metabolites of ifosfamide,
interfere with mitochondrial function and may sequester carnitine, Urinary
excretion of carnitine was measured in five patients before and during a co
ntinuous infusion of ifosfamide over 5 days at a dose of 2.8-3.2 g/m(2) per
day. The excretion of free and total carnitine increased from 85 +/- 53 to
2697 +/- 1393 mu mol/day on the 1st day of chemotherapy and then gradually
decreased, The average loss of carnitine during a chemotherapy cycle amoun
ted to 8.5 mmol. The formation and excretion of esters of carnitine and met
abolites of ifosfamide and/or a decreased renal tubular reabsorption could
account for this marked loss, which might lead to symptomatic carnitine def
iciency after several chemotherapy cycles.