Abstract

Dexamethasone (DEX) is a glucocorticoid commonly used to treat idiopathic sudden sensorineural hearing loss (ISSNHL) and inner ear disorders like Meniere's disease. However, systemic administration of DEX is associated with signifi- cant side effects, such as hypertension and peptic ulcer, highlighting the need for safer and more effective intratympanic (IT) for- mulations and reliable methods for their in vivo evaluation. However, methods to determine DEX in the cochlea require a tissue lyser, uncommon in laboratories for instrumental analyses, and their analytical performances have not been validated. To address these issues, a simple and cost-effective method to determine DEX in murine cochlear tissue was developed using triamcinolone acetonide as the internal standard (IS), acetonitrile as a single extraction solvent, and LC-MS/MS as an instrumental method. The developed method was successfully validated through selectivity, linearity (r² ≥ 0.999 within 1–500 ng/mL), accuracy (rang- ing from 86.8% to 100.2%), precision (≤ 5.8%), matrix effect (91.56% to 104.46%), recovery (93.1% to 104.5%) and the lower limit of quantitation (1.0 ng/mL) following FDA guidelines. This method is expected to contribute to the development of novel formulations for IT delivery of DEX for inner ear disorders.