Compatible spectrophotometric methods for the determination of two antihypertensive mixtures containing hydrochlorothiazide in pharmaceutical preparations

摘要

Simple, rapid, accurate and precise spectrophotometric methods have been developed and subsequently validated for simultaneous determination of telmisartan (I) and bisoprolol fumarate (II), separately, in binary mixtures with hydrochlorothiazide (HCTZ). Isosbestic point technique was the first method adopted for determination of (I) and (HCTZ) mixture, by utilizing zero-order and first derivative spectra (D~1) at 266.0 and 323.0 nm for the total concentration and (I), respectively. The second method was ratio subtraction technique used for determination of bisoprolol fumarate in presence of hydrochlorothiazide at 224.4 nm, using hydrochlorothiazide (10 μg.ml~(-1)) as a divisor. Dual wavelength technique was the third way used for hydrochlorothiazide determination in presence of bisoprolol fumarate, by using the absorbance difference at 266.0 and 277.8 nm. The proposed methods have been validated according to International Conference Harmonization (ICH) guidelines and were found to be valid and suitable for the assay of the cited drugs in raw materials and in combined dosage forms. All the obtained results for the mentioned drugs were statistically compared with those of reference and United State Pharmacopeia for [(I) and (HCTZ)] and [(II) and (HCTZ)] and no significant differences were found.