Valproylcarnitine: a novel drug metabolite identified by fast atom bombardment and thermospray liquid chromatography-mass spectrometry.
Urine samples from three children at different stages of chronic valproate therapy were partially purified using a cation exchange column. A signal consistent with either valproylcarnitine or octanoylcarnitine was observed in one of these extracts by direct fast atom bombardment-mass spectrometry analysis. These isomeric acylcarnitines were synthesized, separated and characterized by thermospray high performance liquid chromatography-mass spectrometry. This new technique was then employed to positively identify intact valproyl-carnitine in the patients' urine samples. The implications of this finding with regard to a mechanism to account for carnitine deficiency in patients receiving valproate are discussed.
D000293:Adolescent; D002331:Carnitine / Q000031:analogs & derivatives* / Q000652:urine; D002648:Child; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006801:Humans; D007536:Isomerism; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D012640:Seizures / Q000188:drug therapy; D014635:Valproic Acid / Q000627:therapeutic use / Q000652:urine
D014635:Valproic Acid; C044923:valproylcarnitine; C008698:octanoylcarnitine; D002331:Carnitine