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.

Two UV-spectrophotometric and one reverse phase high performance liquid chromatography methods have been developed for the simultaneous estimation of amlodipine besilate, losartan potassium and hydrochlorothiazide in tablet dosage form. The first UV spectrophotometric method was a determination using the simultaneous equation method at 236.5, 254 and 271 nm over the concentration range 5-25, 10-50 and 5-25 μg/ml for amlodipine besilate, losartan potassium and hydrochlorothiazide, respectively. The second UV method was a determination using the area under curve method at 231.5-241.5, 249-259 and 266-276 nm over the concentration range of 5-25, 5-25 and 10-50 μg/ml for amlodipine besilate, hydrochlorothiazide and losartan potassium, respectively. In reverse phase high performance liquid chromatography analysis is carried out using 0.025 M phosphate buffer (pH 3.7):acetonitrile (57:43 v/v) as the mobile phase and Kromasil C18 (4.6 mm i.d×250 mm) column as stationery phase with detection wavelength of 232 nm linearity was obtained in the concentration range of 2-14, 20-140 and 5-40 μg/ml for amlodipine besilate, losartan potassium and hydrochlorothiazide, respectively. Both UV-spectrophotometric and reverse phase high performance liquid chromatography methods were statistically validated and can be used for analysis of combined dose tablet formulation containing amlodipine besilate, losartan potassium and hydrochlorothiazide.

A rapid and simple high-performance thin layer chromatography (HPTLC) method with densitometry at 230 nm was developed and validated for simultaneous determination of diphenhydramine hydrochloride (DPH) and naproxen sodium (NPS) from pharmaceutical preparation. The separation was carried out on aluminum plates precoated with silica gel 60 F254 using mobile phase toluene:methanol:glacial acetic acid (7.5:1:0.2, v/v/v). The linearity range lies between 200 and 1200 ng/band for DPH and 1760 and 10,560 ng/band for NPS with correlation coefficients of 0.994 and 0.995, respectively. The Rf value for DPH is 0.20 ± 0.05 and for NPS is 0.61 ± 0.06. % Recoveries of DPH and NPS was in the range of 99.70%–99.95% and 99.63%–99.95%, respectively. Limit of detection value for DPH was 13.21 ng/band and for NPS was 8.03 ng/band. Limit of quantitation value for DPH was 40.06 ng/band and for NPS was 24.34 ng/band. The developed method was validated as per ICH guidelines. In stability testing, DPH was found unstable to acid and alkaline hydrolysis, and DPH and NPS were found unstable to oxidation, whereas both the drugs were stable to neutral and photodegradation. The proposed method was successfully applied for the routine quantitative analysis of dosage form containing DPH and NPS.

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Three simple, accurate and economical methods have been developed for the estimation of norfloxacin and ornidazole in tablet dosage form. First method is based on the simultaneous equations, wavelengths selected for analysis were 273.0 nm (λmax of norfloxacin) and 318.5 nm (λmax of ornidazole), respectively, in 0.1N NaOH. Second method is Q-analysis method, based on absorbance ratio at two selected wavelengths 297.0 nm (iso-absorptive point) and 318.5 nm (λmax of ornidazole). Third method is first order derivative spectroscopy using 297.5 nm (zero cross for norfloxacin) and 264.0 nm (zero cross for ornidazole). The linearity was obtained in the concentration range of 4-20 μg/ml and 5-25 μg/ml for norfloxacin and ornidazole, respectively. The results of the analysis have been validated statistically and by recovery studies.