SENSITIVE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ASSAY FOR NIFEDIPINE IN HUMAN PLASMA UTILIZING ULTRAVIOLET DETECTION

A rapid, simple, sensitive and selective reversed-phase high-performan ce liquid chromatographic (HPLC) technique is reported for the determi nation of nifedipine in human plasma. The procedure involves extractio n of nifedipine from plasma under alkaline conditions (pH 12), separat ion via reversed-phase HPLC and ultraviolet detection (350 nm). The pe ak corresponding to nifedipine was free of interference from its photo degradation products or metabolites. The method was validated over the range 5-250 ng/ml nifedipine using weighted least-squares linear regr ession analysis. Accuracy and precision were within approximately 10% or less over the concentration range, except for the lowest concentrat ion point which, nonetheless, was acceptable and approached 15%. The m inimum quantifiable concentration of nifedipine was determined to be 5 ng/ml. The minimum detectable concentration was in the order of 1 ng/ ml. Analysis of plasma samples collected from healthy volunteers demon strate that this assay is applicable to clinical and pharmacokinetic s tudies.