Spectrophotometeric determination of metoprolol in tablet dosage form

Abstract

Metoprolol, a beta-1 selective adrenegic receptor blocker antihypertensive agent is fairly new in Nigeria. In view of the endemic faking and adulterating of drugs in Nigeria, a simple, quick, and accurate method was developed for its assay. Metoprolol was coupled with 4-chloro-7-nitrobenzo-2-oxa-1, 3 diazole (NBD-Cl) in borate buffer (pH 9) and at a temperature of 100oC. An orange coloured metoprolol-NBD-Cl complex was formed within 10 minutes and the complex was stable for another 20 minutes. The reaction product had a ëmax of 460 nm. The absorbance-concentration plot was rectilinear (0.998) over the concentration range of 5 40 ìg/ml and with a detection limit of 2 ìg/ml. Recovery was 96.3% with RSD of 6.5%.