UTILITY OF SOME π-ACCEPTORS FOR THE SPECTROPHOTOMETRIC DETERMINATION OF TRIMETAZIDINE HYDROCHLORIDE

Abstract

Three simple, quick and sensitive spectrophotometric methods are described for the determination of trimetazidine hydrochloride. The methods are based on the reaction of this drug as an n-donor with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), 7,7,8,8-tetracyano-quinodimethane (TCNQ) and p-chloranil (CL) as π-acceptors to give highly coloured complex species. The colored products are quantitated photometrically at 458, 842 and 545 nm for DDQ, TCNQ and CL, respectively. Optimization of the different experimental conditions is described. Beer's law is obeyed in the concentration ranges 5–50, 1–15 and 10–150 µg ml−1of trimetazidine hydrochloride, but the concentration ranges for best accuracy are: 6.3–50, 2.5–14.4 and 21.4–150 µg ml−1 of drug for the DDQ, TCNQ and CL, respectively. The relative standard deviations are less than 1%. The proposed methods are successfully applied to the determination of trimetazidine in Vastarel tablets. The association constants of the 1 : 1 complexes were: 1540, 400 and 2550 l mol−1 for DDQ, TCNQ and CL, respectively.