A MICROMETHOD FOR THE DETERMINATION OF THE NEW ANTIEPILEPTIC DRUG LEVETIRACETAM (UCB LO59) IN SERUM OR PLASMA BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

An isocratic high performance liquid chromatographic micromethod is de scribed for the quantitation of levetiracetam (ucb L059) in plasma or serum of patients. The chromatography is performed on a 250 x 4 mm I.D . LiChrospher 60 RP-select B, 5-mu m column, eluted with an acetonitri le/50 mM phosphate buffer (15:85 vol/vol, pH 5.6) mobile phase, and le vetiracetam detected using ultraviolet absorbance at 220 nm. The limit of quantitation was 5 mu mol/L and the within-batch and between-batch coefficients of variation were <7%. No interference from commonly pre scribed antiepileptic drugs (carbamazepine and its metabolite carbamaz epine epoxide, ethosuximide, gabapentin, lamotrigine, phenobarbitone, phenytoin, primidone, valproic acid, and vigabatrin) was observed, and thus the method can be used to monitor levetiracetam in patients on p olytherapy antiepileptic drug regimens.