Validation of a HPLC-UV analytical and bioanalytical method for dexamethasone determination in nanoemulsions, porcine nasal mucosa, and mouse plasma and brain tissue

Dexamethasone (DEX) is a synthetic glucocorticoid widely used in the treatment of inflammatory and autoimmune diseases. However, its clinical efficacy is limited by low water solubility, poor bioavailability, and a high incidence of side effects. To overcome these limitations, nanotechnology-based drug delivery systems, such as nanoemulsions, have emerged as promising alternatives, particularly when combined with nasal administration targeting the treatment of neuroinflammation in the central nervous system. This study describes the validation of an analytical and bioanalytical method using high-performance liquid chromatography with ultraviolet detection (HPLC-UV) for the quantification of DEX active pharmaceutical ingredient (API) in nanoemulsions, porcine nasal mucosa, and mouse plasma and brain tissue. The method was validated according to current regulatory guidelines and was based on a procedure previously described in the 7th edition of the Brazilian Pharmacopoeia (2024). The method demonstrated specificity, with no interference from endogenous components of the matrices. Linearity was confirmed in the range of 0.5 to 10.0 µg mL⁻¹ for standard solutions, nanoemulsion, porcine nasal mucosa, and mouse plasma, and from 1.0 to 10.0 µg mL⁻¹ for mouse brain samples, with correlation coefficients (r) greater than 0.99. The method has also been shown to be precise, accurate and with low matrix effect within regulatory acceptance criteria. These results confirm the method’s reliability for determination of DEX in both nanotechnological and biological matrices. The validated method is intended to support future performance studies of nanotechnology-based formulations for nasal administration of DEX.