Spectrophotometric assay of metoclopramide hydrochloride in some pharmaceutical preparations via oxidation coupling reaction


Objectives: A simple and sensitive spectrophotometric method has been developed for the quantitative determination of metoclopramide hydrochloride (MCP) in both pure form and in its pharmaceutical formulations. Materials and methods: The method is based on oxidative coupling reaction of the determined metoclopramide hydrochloride with promethazine in acidic medium (0.1 M hydrochloric acid) by N-chlorosuccinamide (NCS) to form red-violet thiazine.Results: Water-soluble coloured product which showed maximum absorption at 610 nm with a molar absorptivity of 2.05×104 L.mol-1.cm-1. Beer's law was obeyed over the concentration range of 0.1-14 μg/mL. A relative standard deviation of the method was less than 0.5% and the recoveries were obtained in the range of 98-101.5 %. Conclusion: The method does not require either temperature control or solvent extraction, the composition of the coloured product and common excipients on spectrophotometric properties were studied. The proposed method has successfully applied for the determination of metoclopramide in pure and pharmaceutical formulations. The additives did not interfere in this method.