Formulation, characterization, and in vitro/in vivo studies of capsaicin-loaded albumin nanoparticles

Capsaicin (CAP) is a secondary metabolite with high therapeutic potential. It displays several bioactive properties including hypolipidemic, antioxidant, anti-inflammatory and analgesic effects. However, CAP presents toxicity to healthy cells and poor pharmacokinetic profile, which is characterized by toxic metabolites and short half-life. In this study, CAP-loaded albumin nanoparticles were obtained by the desolvation-coacervation method. The preparation process was optimized by the application of a factorial design. Nanoparticles presented diameter of about 200 nm, quasi-spherical morphology, encapsulation efficiency of 98.3 ± 7.4%, and negative zeta potential. The in vitro release assay demonstrated a biphasic profile, characterized by a fast release over 12 h followed by a prolonged release rate. Nanoencapsulated CAP showed significant antioxidant activity in an in vitro assay which was concentration - and time-dependent. In addition, the in vivo study demonstrated for the first time that both free and nanoencapsulated drug reduced TNF-alpha concentrations in the absence of inflammatory stimuli model. These novel findings indicate that albumin nanoparticles are potential CAP carriers and that this new drug formulation may be useful in several conditions, including cancer, inflammation, and neuropathic pain.