C. Palavan

An accurate and precise high performance liquid chromatographic method was developed for quantitative estimation of bosentan in tablet dosage forms. Chromatographic separation of the drug was achieved on a Kromasil C18 column (150 x 4.6 mm; 5µ) by eluting with a mobile phase consisting of phosphate buffer (pH 4.0) and acetonitrile (30:70 v/v) at a flow rate of 1.0 mL/min. The drug in the eluate was monitored by U V detection at 270 nm. The retention time obtained for the drug was 3.54 min. The calibration curve plotted was linear over the range of 25-175 µg/mL of the drug. The validation of the method was done following the ICH guidelines. The proposed method could be applied for determination of bosentan in its tablet dosage forms without any interference from excipients. The method is suitable for routine quality control analysis of bosentan formulations.

An accurate, precise and reproducible high performance liquid chromatographic method was developed for quantitative estimation of emtricitabine, efavirenz and tenofovir disoproxil fumarate simultaneously in tablet dosage forms. Separation of the drugs was achieved within 15.0 min on a Xterra RP-18 column (150 x 4.6 mm; 5µ) by gradient elution using mixtures of ammonium acetate buffer and acetonitrile as the mobile phase. The analytes in the eluate were monitored at 260 nm. The retention times obtained for emtricitabine, efavirenz and tenofovir disoproxil fumarate were 4.611, 9.098 and 7.512 min respectively. The calibration curves were linear over the range of 20.11-60.33 µg/mL for emtricitabine, 60.28-180.45 µg/mL for efavirenz and 30.13-90.18 µg/mL for tenofovir disoproxil fumarate. The performance of the method was validated according to ICH guidelines. The method was found to be suitable for accurate determination of these drugs in tablet dosage forms without any interference from excipients or endogenous substances.

An accurate, precise and reproducible high performance liquid chromatographic method was developed for the simultaneous estimation of lamivudine, zidovudine and nevirapine in pharmaceutical dosage forms. Phenomenex C18 column (250 x 4.6 mm; 5µ) was employed for the separation of drugs. A mixture of 0.02 M trichloroacetic acid (6.8 pH) and methanol in the ratio of 40:60 v/v was used as the mobile phase and pumped at a flow rate of 1ml/min. The detection wavelength was set at 265 nm. The linearity of quantification was observed in the range of 7.5-112.5, 10-150 and 15-225 μg/ml for lamivudine, zidovudine and nevirapine respectively. The proposed method was validated according to ICH guidelines. The method was found to be suitable for simultaneous and accurate determination of these drugs in tablet dosage forms without any interference from the excipients.