Diroximel Fumarate-Loaded Solid Lipid Nanoparticles (DRF-SLNs) as Potential Carriers for the Treatment of Multiple Sclerosis: Preformulation Study

Diroximel fumarate (DRF) is an orally administered prodrug used in multiple sclerosis (MS) treatment. Although it exhibits better gastrointestinal (GI) tolerability than its analogues, many patients still discontinue therapy due to frequent GI adverse events. To overcome these limitations, alternative drug delivery systems that bypass the GI tract are needed. Direct nose-to-brain delivery represents a promising approach to circumvent the blood–brain barrier and target the central nervous system; however, limited nasal mucosal absorption and the small volume of the nasal cavity pose significant challenges. Solid lipid nanoparticles (SLNs) can potentially overcome these obstacles by enhancing drug bioavailability and protecting against enzymatic degradation. This research aimed to develop an innovative intranasal nanoformulation of DRF to improve brain targeting and patient compliance. DRF-loaded SLNs were prepared using a solvent-diffusion technique with stearic acid as the lipid phase and Poloxamer 188 as the surfactant. The obtained nanoparticles displayed favorable technological characteristics, with a mean diameter of 210 nm, a polydispersity index of 0.17, and a zeta potential of −36 mV, suggesting good long-term stability. Interactions between SLNs and biomembrane models (MLV) were also studied to elucidate their cellular uptake mechanism. Future work will focus on evaluating the in vivo efficacy of this novel nanoformulation.