LAUSR

BACKGROUND Two fixed-dose combination tablets of amlodipine with bisoprolol and amlodipine with candesartan were recently approved for the treatment of hypertension. OBJECTIVE Three UV spectrophotometric analytical methods were developed for the estimation of the above drugs in their combination mixtures. METHODS For amlodipine and bisoprolol mixture, amlodipine was quantified directly by zero-order spectrophotometric method at 360 nm without interference from bisoprolol, whereas, bisoprolol was quantified by the ratio difference spectrophotometric method through calculating the difference between the amplitude values of the ratio spectra at 226 and 215 nm. For amlodipine and candesartan mixture, amlodipine was quantified directly by zero-order spectrophotometric method at 360 nm without interference from candesartan, whereas, candesartan was quantified by the first derivative of ratio spectra method by measuring the amplitude values of the derived spectra at 259 nm. RESULTS The proposed methods were successfully applied for quantitative analysis of amlodipine with bisoprolol and amlodipine with candesartan in their synthetic laboratory prepared mixtures and pharmaceutical tablets with acceptable results in terms of accuracy and precision. CONCLUSION AND HIGHLIGHTS Simple, accurate and environmentally friendly spectrophotometric methods were described for selective determination of the investigated drugs in their fixed dose combinations.