Simultaneous Spectrophotometric Estimation of the Amlodipine Besylate and Hydrochlorothiazide in Pharmaceutical Preparations and Biological Samples

Two new simple, selective economical and reproducible UV spectrophotometeric method simultaneous estimation of two component drug mixture of Amlodipine besylate (AB) and hydrochlorothiazide (HCT) in pharmaceutical preparation, blood sample and urine has been developed. The first method depends on first derivative method at 245 and 238 nm for AB and HCT also in plasma and urine respectively. The linearity over the concentration ranges 2.5- 17.5 μg/ml for both the drugs AB and HCT. The second method is based on two wavelength method, which uses the difference of absorbance value at 271 nm and 395 nm for estimation of Hydrochlorothiazide (HCT) and absorbance at 363 nm for amlodipine besylate (AB). In formulation, plasma and urine Methanol: water (50:50 v/v) was used as solvent, in which Amlodipine besylate and Hydrochlorothiazide shows linearity in the range of 2.5-17.5 μg/ml for both the drugs respectively. Standard deviation was <1.5 in the assay of tablets. This method validated and the result was compared statically. The %RSD value was satisfactorily low and recovery was close to 100% indicating reproducibility and accuracy of this method. Both the drug obeys Beer’s law in the concentration range employed for analysis. Full analytical validation of this method performed according to International Conference on Harmonization Q2 (R1) and USFDA Bioanalytical methods guidelines. These proposed methods were found to be simple, accurate, rapid, specific, economic and advantageous in having lower limit of detection.