Spectrophotometric Methods for the Determination of Nimodipine in Pure and in Pharmaceutical Preparations

Four simple, sensitive, accurate and rapid visible spectrophotometric methods (A, B, C and D) have been developed for the estimation of nimodipine in both in pure and pharmaceutical preparations. They are based on the diazotization of reduced nimodipine with nitrous acid followed by coupling with acetylacetone (Method A), diphenylamine (Method B), citrazinic acid (Method C) and chromotropic acid (Method D) to form respective colored azodyes and exhibiting absorption maxima (ëmax) at 420, 540, 440 and 520 nm, respectively. The colored azodyes formed are stable for more than 2h. Beer s law was obeyed in the concentration range of 0- 35, 0–25, 0-35 and 0-35 μg/mL for methods A, B, C and D, respectively. The results of the four analyses have been validated statistically and by recovery studies. The results obtained in the proposed methods are in good agreements with labeled amounts, when marketed pharmaceutical preparations are analyzed.