Three new spectrophotometric methods (A, B and C) and one new high performance liquid chromatography (HPLC) method (D) for the quantitative analysis of bosentan (BSN) in pharmaceutical dosage forms have been described. The method A involves the oxidation of bosentan with ammonium molybdate in acidic medium which results in a blue-colored product. The methods B and C are based on the formation of yellow colored ion-pair complexes with 2, 4-dinitrophenol and bromocresol green, respectively. In method D, the determination of bosentan was carried out on Agilent C18 column (150 mm × 4.6 mm I.D., 5 µm) in isocratic mode with methanol and ammonium acetate buffer (60:40 v/v) as mobile phase. The flow rate was 1.0 mL/min and eluent was monitored at 227 nm. The retention time of bosentan was 2.449 min. Under the optimized experimental conditions, Beer's plot showed good correlation in the concentration ranges of 2-30, 5-30, 2.5-50 and 5-100 µg/mL for methods A, B, C and D respectively. The methods were validated in accordance with the International Conference on Harmonization (ICH) guidelines. These methods were found to be sensitive, accurate, precise and robust and were successfully applied to the estimation of tablet dosage forms containing bosentan. There was no interference from the tablet excipients.
Bosentan, Spectrophotometry, HPLC, Tablet dosage forms, Analysis