Validated Stability Indicating High Performance Liquid Chromatographic Method for the Determination of Ambrisentan in Pharmaceutical Dosage Form

A simple, sensitive, selective and precise stability indicating HPLC method is developed and validated for the assay of ambrisentan in pharmaceutical dosage form. Separation of the drug was achieved on Agilent Zorbax C18 column (250 mm × 4.6 mm I.D., 5 μm particle size) under the isocratic mode of elution. The solvent system consisted of 0.1M potassium dihydrogen phosphate buffer (pH was adjusted to 4.4 with orthophosphoric acid) and methanol (30:70 v/v) at a flow rate of 1.0 ml/min. The method was carried out in the absorbance mode at 210 nm. The method was statistically validated according to International Conference on Harmonization guideline. Ambrisentan was subjected to stress degradation studies under acidic, basic, oxidative, thermal and photolytic conditions. The system was found to give compact peak for ambrisentan (Retention time is 3.315 min). The method was linear in the range of 1 - 150 µg/ml. The linear regression data for the calibration plot showed good relationship (r2 = 0.9996). The relative standard deviation and mean recovery values at different concentration levels were within limits. The performance of the method was not changed when small variations in the experimental conditions were made. Degradation products resulting from stress degradation studies did not interfere with the detection of ambrisentan. The proposed stability indicting HPLC method is simple, precise, accurate, robust and selective. This method can be used for quantification of ambrisentan in bulk drug and in pharmaceutical dosage forms.