Preformulation, Characterization, and In Vitro Release Studies of Caffeine-Loaded Solid Lipid Nanoparticles.

Encapsulation of active agents in solid lipid nanoparticles (SLNs) is an alternative to other controlled release systems for topical delivery. In this study, caffeine was encapsulated in SLNs to produce a delivery system with controlled release. Caffeine-loaded SLNs (Caf-SLNs) were prepared using the double emulsion method with homogenization and ultrasonication. The characterization studies were performed using dynamic light scattering (DLS), zeta potential, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) analyses. The encapsulation efficiency tests were performed using UV spectrophotometry. In vitro release studies were conducted using a dialysis bag technique and high-performance liquid chromatography (HPLC) for the quantification of caffeine (Caf). The results from the DLS analysis showed that all formulations had a polydispersity index <0.3 with particle sizes <210 nm. The DSC and SEM results showed that Caf was dispersed in the SLNs. The encapsulation efficiency was 49.22%. The release studies indicated that after an initial burst at 3 min, the SLNs released Caf in a controlled manner over a 6-h period. Taken together, the SLNs can be used as a carrier for the topical delivery of Caf.