P. Srinivasa Babu

Hypertension (HT) is a very common disorder, particularly for past middle age. It is not a disease in itself, but is an important risk factor for cardiovascular mortality and morbidity. For improved treatment of hypertension, Telmisartan and Benidipine HCl is the newer combination in market, this combination was developed to improve medication for Stage II hypertension. The aim of this review is to focus on comprehensive update of different analytical methods used for estimation of anti-hypertensive drugs like Telmisartan and Benidipine HCl for the treatment of hypertension. This review delivers a detail description on different analytical methods like UV and RP-HPLC for Telmisartan and Benidipine HCl individually and combination with other drugs. For this review, data searches were conducted by scientific papers in the literature as well as in official compendium. All reported methods are found to be simple, accurate, economic, precise and reproducible in nature.

A simple, specific, accurate and precise reverse phase high performance liquid chromatographic method was developed and validated for the estimation of Venlafaxine hydrochloride in pure and Pharmaceutical dosage form. Kromasil C18 column having 150 mm x 4.6 mm internal diameter, 5 µm particle sizes in isocratic mode with mobile phase containing mixture of methanol and water in the ratio of 65:35 v/v was used. The flow rate was 1.0 ml/min and effluents were monitored at 225 nm. The retention time for Venlafaxine was 2.424 min. The method was validated for linearity, accuracy, precision, specificity, limit of detection, limit of quantification and robustness. Limit of detection and limit of quantification were found 2.97µg/ml and 9.92 µg/ml respectively and recovery of Venlafaxine from tablet formulation was found 100.4 %. The proposed method was successfully applied for the quantitative determination of Venlafaxine in tablet dosage form.

A simple reverse phase specific and selective high performance liquid chromatographic method for determination of Exemestane in Exemestane tablets has been developed and validated with Isocratic elution and UV detection. Chromatographic separation was achieved by using Hypersil, C-18, 150 X 4.6mm, 5µ column with a mixture of Acetonitrile and Purified water in the ratio of 35:65, filter and degas the mobile phase same is used as diluent. Detection was at 249 nm. By this method all known and unknown Impurity & Degradation products are well separated from Exemestane main peak.  Peak purity factor for Exemestane peak is not less than 99.0%. Both the Precision (System Precision, Method Precision, Intermediate Precision) and Linearity were within acceptable range. Response was a linear function between concentration and area of peak over the   range from 50% to 150% of assay concentration for Exemestane. It can be concluded that the Exemestane Peak is found to be degraded more in acid, alkali and peroxide stress condition. Exemestane Peak purity factor was more than 99.0% and all degradation product formed were well separated from Exemestane Peak. By this it was found that this method is robust and system suitability test was established and related parameters are recorded. This method is validated hence this method can be used for routine analysis of stability sample.

The objective of the present research work was to simultaneously separate the anti-hypertensive agents, Amlodipine and Valsartan and develop a validated analytical method for simultaneous quantitative determination of amlodipine and valsartan in tablet dosage form. A simple, rapid, precise and selective chromatographic method was developed and validated for separation and determination amlodipine and valsartan in tablet preparations. The anti-hypertensive agents were analyzed by Symmetry C18, (150 × 3.4 mm, 5 µ), Shimadzu LC-2010CHT Prominence Liquid Chromatograph and a mobile phase constituted of 10 mM Buffer (pH 3.0): methanol (50:50, v/v). The flow rate was 1.0 mL/min and the analysis were performed using UV- Vis detector at 237nm. The anti-hypertensive agents, Amlodipine and Valsartan were separated within 10 min. Amlodipine and Valsartan showed retention time of 5.06 and 8.28 min respectively. The drugs were found to obey Beer’s law in the concentration range of 100 ppm of amlodipine and 128 ppm of valsartan. The developed assay method is selective, precise and accurate. The method has been successfully applied for determination of Amlodipine and Valsartan in pharmaceutical combination tablet dosage form. This developed method is sensitive, fast and simple with excellent peak symmetry and high resolution.

A novel, convenient, accurate, precise and reproducible reverse phase high performance liquid chromatography was developed and validated for the estimation of Vilazodone in bulk and pharmaceutical tablet dosage form. Objective was achieved under optimized chromatographic conditions on Shimadzu LC-20AT Prominence Liquid Chromatograph with Welchrom C18 isocratic column, (250 mm × 4.6 mm i.d., particle size 5 μm, maintained at ambient temperature), is used as stationary phase. An isocratic mode with mobile phase consisting of Acetonitrile: Water (50:50 v/v), with apparent pH of 3.3, at a flow rate of 1.0 mL/minutes. The effluent was monitored at 240 nm using Shimadzu SPD-20A prominence UV-Vis detector. The retention time of Vilazodone was found to be 4.103 minutes. The linearity range was found to be 1-5 μg/mL with correlation coefficient (R2) is 0.999. Validation parameters such as specificity, linearity, precision, accuracy, and robustness, limit of detection (LOD) and limit of quantitation (LOQ) were evaluated for the method according to the International Conference on Harmonization ICH Q2 (R1) guidelines. The LOD and the LOQ were found to be 0.044 μg/mL and 0.135 μg/mL respectively. Recovery of Vilazodone was found to be in the range of 99.80 % - 99.92 %. The method was validated statistically using the % RSD and the values are found to be within the limits. Therefore this method was conveniently and easily applied for the quantitative determination of Vilazodone in pharmaceutical dosage forms.