A simple, specific, accurate and stability indicating reversed phase high performance liquid chromatographic method was developed for the simultaneous determination of atorvastatin calcium and amlodipine besylate in tablet dosage forms. A phenomenex Gemini C-18, 5 μm column having 250×4.6 mm i.d. in isocratic mode, with mobile phase containing 0.02 M potassium dihydrogen phosphate:acetonitrile:methanol (30:10:60, v/v/v) adjusted to pH 4 using ortho phosphoric acid was used. The flow rate was 1.0 ml/min and effluents were monitored at 240 nm. The retention times of atorvastatin calcium and amlodipine besylate were 11.6 min and 4.5 min, respectively. The calibration curves were linear in the concentration range of 0.08-20 μg/ml for atorvastatin calcium and 0.1-20 μg/ml for amlodipine besylate. Atorvastatin calcium and amlodipine besylate stock solutions were subjected to acid and alkali hydrolysis, chemical oxidation and dry heat degradation. The degraded product peaks were well resolved from the pure drug peak with significant difference in their retention time values. The proposed method was validated and successfully applied to the estimation of atorvastatin calcium and amlodipine besylate in combined tablet dosage forms.

A simple, specifi c and accurate reverse phase high performance liquid chromatographic method was developed for the simultaneous determination of atorvastatin calcium and aspirin in capsule dosage forms. A phenomenex Gemini C-18, 5 µm column having 250 x 4.6 mm i.d. in isocratic mode, with mobile phase containing 0.02 M potassiumdihydrogen phosphate: methanol (20:80) adjusted to pH 4 using ortho phosphoric acid was used. The fl ow rate was 1.0 ml/ min and effl uents were monitored at 240 nm. The retention times of atorvastatin calcium and aspirin were 5.4 min and 3.4 min, respectively. The linearity for atorvastatin calcium and aspirin were in the range of 0.5-4 µg/ml and 5-25 µg/ml, respectively. The recoveries of atorvastatin calcium and aspirin were found to be in the range of 98.02-100.68% and 98.38-101.42%, respectively. The proposed method was validated and successfully applied to the estimation of atorvastatin calcium and aspirin in combined capsule dosage forms.

A simple, specific, accurate, and precise reverse phase high performance liquid chromatographic method was developed and validated for the estimation of venlafaxine hydrochloride in tablet dosage forms. A Phenomenex Gemini C-18, 5 μm column having 250 × 4.6 mm i.d. in isocratic mode, with mobile phase containing methanol: 0.05 M potassium dihydrogen orthophosphate (70:30, v/v; pH 6.2) was used. The flow rate was 1.0 ml/min and effluents were monitored at 226 nm. Carbamazepine was used as an internal standard. The retention time of venlafaxine hydrochloride and carbamazepine were 3.7 min and 5.3 min, respectively. The method was validated for specificity, linearity, accuracy, precision, limit of quantification, limit of detection, robustness and solution stability. Limit of detection and limit of quantification for estimation of venlafaxine hydrochloride were found to be 100 ng/ml and 300 ng/ml, respectively. Recoveries of venlafaxine hydrochloride in tablet formulations were found to be in the range of 99.02-101.68%. Proposed method was successfully applied for the quantitative determination of venlafaxine hydrochloride in tablet dosage forms.

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A simple and accurate method for the analysis of ibuprofen (IBU) and famotidine (FAM) in their combined dosage form was developed using second order derivative spectrophotometery. IBU and FAM were quantified using second derivative responses at 272.8 nm and 290 nm in the spectra of their solutions in methanol. The calibration curves were linear in the concentration range of 100-600 lg/mL for IBU and 5-25 lg/mL for FAM. The method was validated and found to be accurate and precise. Developed method was successfully applied for the estimation of IBU and FAM in their combined dosage form.