Design of Experiment Assisted UV-Visible Spectrophotometric and RP-HPLC Method Development for Ambrisentan Estimation in Bulk and Formulations

Design of experiment (DOE) approach reinforces the robustness of the method being developed. This was employed for UV-visible (200-400 nm and 400-800 nm respectively) and RP-HPLC method development using C18 inertsil column and optimization of variables for ambrisentan (ABN) estimation in bulk and formulations. A two-level full factorial design assisted development of a visible spectroscopic method based on the principle of oxidation and coupling reaction of ABN with 3-methyl-2-benzothiazolinone hydrazone (MBTH reagent) in presence of FeCl3 to form bluish-green chromogen which is detectable in the visible range. second method estimates ABN in bulk and tablet dosage forms in the UV range using pH 7.4 phosphate buffer and the third one is a rapid, simple, stability indicating RP-HPLC method using a degassed mixture of orthophosphoric acid (OPA, 0.05M): acetonitrile (40:60) as mobile phase with water: acetonitrile (30:70) as diluent using PDA detector set at 264 nm for routine estimation of ABN in bulk and pharmaceutical dosage forms. Experimental design, data analysis and contour plots were developed using Minitab ® 16.2.4 trial version (Minitab Inc). The percent assay of ABN detected by visible spectroscopy was 100.58±101.37% with RSD value 0.38%, by UV spectroscopy it was 99.1±99.8% with 0.5% RSD value and by RP-HPLC it was found 100.9%. The values of method validation parameters of three methodologies were found within the acceptance limits. The three methodologies could be regarded as specific, accurate, precise, with significant stability and robustness for routine estimation of ABN in bulk and tablet dosage forms.