The present work describes a validated reverse phase high performance liquid chromatographic method for simultaneous estimation of telmisartan and hydrochlorothiazide in tablet formulation. Chromatography was performed on a ODS Hypersil C18 (25 cm×4.6 mm I.D) column from thermo in isocratic mode with mobile phase containing acetonitrile:0.05 M KH 2 PO 4 pH 3.0 (60:40). The flow rate was 1.0 ml/min and the eluent was monitored at 271 nm. The selected chromatographic conditions were found to effectively separate telmisartan (RT-5.19 min) and hydrochlorothiazide (RT-2.97 min). Linearity for telmisartan and hydrochlorothiazide were found in the range of 4.1-20.48 µg/ml and 1.28-6.4 µg/ml, respectively. The proposed method was found to be accurate, precise, reproducible and specific and can be used for simultaneous analysis of these drugs in tablet formulation.

Three simple, precise and economical UV methods have been developed for the estimation of itopride hydrochloride in pharmaceutical formulations. Itopride hydrochloride in distilled water shows the maximum absorbance at 258.0 nm (Method A) and in first order derivative spectra of the same shows sharp peak at 247.0 nm, when n = 1 (Method B). Method C utilises area under curve (AUC) in the wavelength range from 262.0-254.0 nm for analysis of itopride hydrochloride. The drug was found to obey Beer-Lambert’s law in the concentration range of 5-50 μg/mL for all three proposed methods. Results of the analysis were validated statistically and recovery studies were found to be satisfactory.

A simple, specific, accurate, precise and reproducible method has been developed and validated for the simultaneous estimation of hydrochlorothiazide and olmesartan medoxomil in combined dosage form by UV spectrophotometric method. UV spectrophotometric method includes simultaneous equation method (Method I) 271.5 nm and 257.0 nm λ max of both the drugs were selected, absorbance Ratio method (Method II) 261.5 nm an isoabsorptive wavelength and 257.0 nm were selected for estimation of hydrochlorothiazide and olmesartan medoxomil respectively and Three wavelength method (Method III), two wavelengths were selected such that hydrochlorothiazide give same absorbances (263.8 and 278.4 nm) at two selected wavelength while third wavelength (316.5 nm) was such that olmesartan gives nearly zero absorbance. The two drugs follow Beer's law over the concentration range of 5-25 µg/mL. The % recoveries of the both the drugs were found to be nearly 100 % representing the accuracy of the proposed methods. Validation of the proposed methods was carried out for its accuracy, precision, specificity and ruggedness according to ICH guidelines. The proposed methods can be successfully applied in routine work for the determination of hydrochlorothiazide and olmesartan medoximil in combined dosage form.

The present work describes a two-wavelength method for simultaneous determination of metoprolol and hydrochlorthiazide in fixed dose combination tablet. The wavelengths selected for method were 257.8 nm, 282.9 nm and 315.0 nm. The absorbance difference at first two wavelengths was used for determination of metoprolol and the latter was used for determination of hydrochlorthiazide. The recovery value for the drugs from the tablet matrix was found to be 100.55% (metoprolol) and 99.97% (comparison with standard) and 98.09% (E1%, 1cm) for hydrochlorthiazide. The method has an advantage that hydrochlorthiazide can be estimated in combination, as there is no interference of metoprolol at 315.0 nm. The method was evaluated statistically for its accuracy and precision.