Photodegradation of methylcobalamin and its determination in a commercial formulation

Methylcobalamin is a highly photolabile and unstable molecule and hence, studies regarding photodegradation of methylcobalamin were carried out.. In order to investigate the stability studies, the drug was subjected to photodegradation by exposing it to different light conditions in the validated photostability chamber as per ICH Q1B guideline. The drug was found to be less degraded in the blue light and was more prone to degradation under fluorescent light. Validated stability indicating liquid chromatography method was used for separating the methylcobalamin and its degradation products. The methylcobalamin peak with a retention time of 2.978 min was observed to decrease with a commensurate increase in a degradant peak at 4 min. The observed degradant peak was suspected to be hydroxocobalamin and was further confirmed by molecular weight determination. The fractions collected from high performance liquid chromatography were later injected into mass detector to determine the mass of the degradation products, which was found to be 665.78 amu.