A validated, stability-indicating method for the assay of dexamethasone in drug substance and drug product analyses, and the assay of preservatives in drug product

A new high-performance liquid chromatographic (HPLC) procedure for the determination of dexamethasone, impurities, degradation products and product preservatives is described. A three-stage, linear gradient with UV detection at 240 nm allows the analysis of dexamethasone drug substance and dexamethasone in two formulated products, using the same chromatographic system. The Limit of Quantitation (LOQ) of dexamethasone impurities in drug substance is 0.05%, and 0.1% for dexamethasone degradation products in formulated products. The method is linear, precise, accurate and robust. Sample preparations are simple, and are accomplished without the use of an internal standard. Several degradation products of stressed dexamethasone have been identified.