Sri Teguh Rahayu, Yahdiana Harahap dan Harmita
Valproic acid is one of mostly used antiepileptic drug which have side effects, so it is highly recommended to evaluate its plasma concentration The aim of the research was to validate a method for the determination valproic acid in plasma in-vitro and in-vivo after derivatization with 2,4-dibromasetofenon using high performance liquid chromatography-photo diode array. Valproic acid and internal standard nonanoic acid were extracted from plasma sample with ethyl acetate, after that supernatan was neutralizatied and evaporated and dried residue reconsituted in derivate-catalyst solution then derivatized at 75ºC for 25 minutes. The resulting derivatives were separated on a Sunfire C18 (250 mm x 4.6, 5 μm) reverse phase column with acetonitrile-water (73:27) as mobile phase, were detected at 294 nm and analysis were run at flow rate 1.5 mL/minute. The calibration curve in plasma in-vitro (Y =0.0123 + 0.0085 x) presented good linier (r = 0.9999) between 4.75-237.75 μg/mL with LLOQ 4.75 μg/mL. The mean of relative recovery at low concentration, medium concentration and high concentration are 100.67%, 99.78%, and 93.16 %, respectively. Intra- and inter- day coefficient of variation and percent error value of the assay method not more than 15%. The presented method was might be applied to the determine of the valproic acid concentration in plasma after oral administration of 500 mg sodium divalproate.
