A Review on Nasal Self-Emulsifying Drug Delivery Systems: An Alternative Approach to Improve Brain Bioavailability of Poorly Water-Soluble Drugs

Neurotherapeutic drugs fail to reach the site of action due to poor bioavailability, poor water solubility, limited permeability, hepatic first-pass metabolism, and the blood-brain barrier. The nasal cavity allows drugs to be delivered directly to the brain, bypassing the blood-brain barrier. The nasal cavity also avoids hepatic first-pass metabolism, enhancing the systemic bioavailability of highly metabolized substances. As a result, most neurotherapeutics have physicochemical properties that necessitate their formulation in lipidic nanosystems as self-emulsifying drug delivery systems (SEDDS). These are isotropic mixes of oils, surfactants, and co-surfactants that, when diluted in water, produce micro or nanoemulsions containing high quantities of lipophilic medicines. SEDDS should prevent drug precipitation at absorption sites, boost permeability through absorptive membranes, and improve labile drug stability against enzymatic activity. When the benefits of SEDDS and the intranasal route for brain delivery are combined, an increase in medication brain targeting and bioavailability might be expected.