Identification, Synthesis, and Characterization of N‐Formyl Mirabegron: A New Degradation Product Formed by Formic Acid Impurity in Pharmaceutical Excipients

Abstract

This study demonstrated the impact of formic acid (FAc), a common reactive impurity in pharmaceutical excipients, on the stability of mirabegron (MB). The investigation of MB‐excipient compatibility tests revealed the formation of a new degradation product, FAc‐DP, at 0.2% after 7 days of isothermal stress at 55°C. FAc‐DP was synthesized and characterized as N‐formyl MB using liquid chromatography–mass spectrometry (LC‐MS) and both 1D and 2D nuclear magnetic resonance spectroscopy (NMR).