Assay of anti-coagulant drug warfarin sodium in pharmaceutical formulation and human biological fluids by square-wave adsorptive cathodic stripping voltammetry

The cyclic voltammogram of the anti-coagulant drug warfarin sodium at the hanging mercury drop electrode exhibited a well-defined single two-electron irreversible peak over the pH range 4-7, which may be attributed to the reduction of the C=O double bond of the drug molecule. Based on the interfacial adsorptive character of the drug onto the mercury electrode surface, a square-wave cathodic stripping procedure was optimized for its trace determination. The calibration plot was linear over the concentration range of 5 x 10(-9) to 4 x 10(-7) M warfarin sodium in Britton-Robinson (B-R) buffer of pH 5, with limits of detection and quantitation of 6.5 x 10(-10) and 2.1 x 10(-9) M warfarin sodium, respectively. The proposed procedure was successfully applied for assay of warfarin sodium in its pharmaceutical formulation "hemofarin tablets", human serum and urine without the necessity for sample pretreatment or time-consuming extraction or evaporation steps, prior to assay of the drug. Limits of detection of 1.1 x 10(-9) and 1.3 x 10(-8) M warfarin sodium were achieved, while limits of quanitation of 3.7 x 10(-9) and 4.3 x 10(-s) M warfarin sodium were estimated in human serum and urine, respectively. The pharmacokinetic profiles of the drug were studied and the estimated pharmacokinetic parameters were favorably compared with those reported in literature. (C) 2004 Elsevier B.V. All rights reserved.