Spectrophotometric Determination of Telmisartan

As studied by spectrophotomety, a complex with composition ratio of 1 to 2 was formed by the charge-transfer reaction between telmisartan and alizarin, having its absorption maximum at the wavelength of 548 nm. Linear relationshiop between values of absorbance and mass concentration of telmisartan was obtained in the range of 16-240 mg·L-1, with apparent molar absorptivity of 2.34×103L·mol-1·cm-1. Based on these facts, a method of spectrophotometric determination of telmisartan was proposed and used in the analysis of drug samples of telmisartan capsules and tablets for their telmisartan contents, giving results in consistency with those values given in literature. Tests for precision and recovery were performed by standard addition method using these drug samples as matrixes. Values of recovery found were 99.5% for the capsules and 99.8% for the tablets.