Determination of Diclofenac Sodium in Human Plasma by Reversed-Phase Liquid Chromatography

Abstract Following a detailed study, a simple, rapid and accurate reversed-phase liquid chromatographic method has been developed for the determination of diclofenac sodium in human plasma. The sample is separated isocratically within 7 min using an octadecyl-bonded silica column and a mobile phase of methanol and sodium acetate buffer (68:32, v/v; pH 4.2). The compounds were quantitated using a ultraviolet detector operated at 274 nm which allowed determination of 0.10 – 2.50 μg/ml of diclofenac sodium with high reproducibility. The limit of detection is 0.03 μg/ml. Intra-day and inter-day coefficients of variation for assaying the plasma sample containing 0.20 μg/ml concentration of diclofenac sodium were 7.4% (n=9) and 7.6% (n=7), respectively. The extraction efficiency of diclofenac sodium were 91.3 – 93.2% for plasma. The method has been used to determine diclofenac sodium in the plasma samples from ten volunteers and provide data on the pharmacokinetics of the drug.