Spectrophotometric determination of nifedipine in pharmaceutical formulations, serum and urine samples via oxidative coupling reaction

Two rapid, simple, sensitive and selective spectrophotometric methods have been developed for the quantitative estimation of nifedipine in pharmaceutical formulations and different human body fluids (serum and urine). The proposed methods are based on the reduction of the nitro group to amino group of the drug. The resulting amine was then subjected to proposed methods. Method A is based on the oxidation followed by coupling of nifedipine with 3- methyl-2-benzothiazolinone hydrazone (MBTH) in presence of ferric chloride (FeCl3) to form green colored chromogen at 685 nm. Method B is based on the formation of oxidative coupling reaction between the corresponding drug and brucine - NaIO4 to form violet colored chromogen at 546 nm. The procedures described were applied successfully to the determination of the compound in their dosage forms and body fluids. The results showed that the proposed procedures compared favorably with reference method are satisfactory sensitive, accurate and precise. The optical characteristics such as Beer's law limits, molar absorptivity, Sandell's sensitivity and various statistical data are reported. The results of the analysis for the two methods have been validated statistically and by recovery studies.