Metoclopramide as a coupling agent for the Kinetic - spectroscopic assay of methyldopa drug

Abstract

A spectrophotometric method has been proposed for the determination of methyldopa in pharmaceutical dosage forms. The method is based on the diazotization reaction of metoclopramide hydrochloride (MCH) and coupling of the diazotized reagent with methyldopa (MDP) to give intense green colored product during this reaction is measured at 465 nm as a function of time. Variable parameters such as temperature, reaction time and concentration of the reactants have been analyzed and optimized. The kinetic study involves initial rate and fixed time (20 minutes) procedures for constructing the calibration graphs to determine the concentration of MDP. Under the proposed optimum condition, Beer’s law was obeyed in the concentration range of 1-60 μg mL-1. The good correlation coefficients and low relative standard deviation assert the applicability of this method. The procedure was characterized by its simplicity with accuracy and precision.