Enzymatic Spectrophotometric Determination of Metoclopramide Hydrochloride

It was found that the catalytic effect of hemoglobin (Hb) on the oxidation decoloration of acid chrome blue K by H2O2 in an ammoniacal buffer medium of pH 9.5 was inhibited by the drug “Metoclopramide”. Rate of inhibition (I%) of Metoclopramide on the catalytic reaction was calculated from values of absorbance of reagent blank solution (A0), absorbance of solution added with Hb (A1) and absorbance of solution added with Hb and Metoclopramide (A2), measured at the wavelength of absorption maximum of acid chrome blue K (551 nm) by the given formula. Linear relationship between values of I% and concentration of Metoclopramide was obtained in the range of 3.0×10-6-1.2×10-4mol·L-1. Detection limit (3s/k) of the method was found to be 2.8×10-8mol·L-1. Precision was tested at the concentration level of 4.0×10-5mol·L-1, giving value of RSD (n=11) 4.6%. Based on these facts, the method was proposed to be used for analysis of injections of the drug for their contents of Metoclopramide giving results in consistency with the labelled values.