Abstract
Candesartan cilexetil (CND, an angiotensin II receptor blocker), and hydrochlorothiazide (HCT, a diuretic of the class of benzothiadiazines) are co-formulated in a single-dose combination for the treatment of hypertensive patients whose blood pressure is not adequately controlled on either component monotherapy. In this work, two multivariate calibration methods were applied for simultaneous spectrophotometric determination of CND and HCT in their combined pharmaceutical tablets The multivariate methods are principal component regression (PCR) and partial least squares (PLS). Both methods are useful in spectral analysis because of the simultaneous inclusion of many spectral wavelengths instead of the single wavelength used in derivative spectrophotometry. The optimum assay conditions were established and the proposed methods were successfully applied for the assay of the two drugs in an independent validation set and combined pharmaceutical tablets with excellent recoveries. No interference was observed from common pharmaceutical additives. The results were favorably compared with those obtained by a reference HPLC method.