Diazo coupling for the determination of selexipag by visible spectrophotometry

Abstract

Aim and Objective: The aim and objective of this study were to develop a spectrophotometric method for the assay of selexipag (selective IP prostacyclin receptor agonist indicated for the treatment of pulmonary arterial hypertension) in pure and pharmaceutical formulations so that it will be an alternative quantitative method to chromatographic methods which require large quantities of organic solvents, where some are with hazardous and toxic properties. Materials and Methods: The method is based on the diazo coupling of selexipag with diazotized p-nitroaniline in alkaline medium to form a stable green-colored and water-soluble azo dye with a maximum absorption at 510 nm. Optimization of reaction conditions was carried out to get highly sensitive and stable colored complex. Results and Discussion: Beer’s law is obeyed over the concentration range of 2–12 μg/mL with a molar absorptivity of 3.33 × 104 L/mol/cm. The limit of detection was 0.35 μg/mL and limit of quantification was 1.0 μg/mL. The results demonstrated that the procedure is accurate, precise, and reproducible (relative standard deviation <2%). Conclusions: This method was tested and validated for various parameters according to the current ICH guidelines.