Identification and characterization of unknown photo-oxidation degradation components of ganciclovir by high-performance liquid chromatography and quadrupole time-of-flight mass spectrometry

Ganciclovir (GCV) is an antiviral drug used to treat cytomegalovirus infections associated with AIDS. The study of the GCV drug substance under photo-oxidation stress conditions identified five impurities. This study aims to interpret the chemical structures of the photo-oxidation products using quadrupole time-of-flight (Q-TOF) mass spectrometry. An optimized chromatographic technique employing reverse-phase high-performance liquid chromatography with photodiode array detection was used to identify the degradation products of GCV. This technique utilized an Endurus Phenyl-hexyl HP column with an eluent mixture of acetonitrile, methanol, and 1 M ammonium formate (pH 3.2). GCV's photo-oxidation products were effectively separated, achieving a resolution higher than 2.0. The Q-TOF mass spectrometry analysis characterized the five degradation products, which included 8-Oxo GCV, secondary degradation of 8-Oxo GCV, guanine, and one dehydrogenated compound. These new impurities require special attention because the drug's potency and impurity levels significantly influence the quality, safety, and effectiveness of pharmaceutical products.