(-)-linalool-Loaded Polymeric Nanocapsules Are a Potential Candidate to Fibromyalgia Treatment

Fibromyalgia (FM) is a chronic disease that has as main characteristic generalized musculoskeletal pain, which can cause physical and emotional problems to patients. However, pharmacological therapies show side effects that hamper the adhesion to treatment. Given this, (-)-linalool (LIN), a monoterpene with several therapeutic properties already reported in scientific literature as anti-depressive, antinociceptive, anti-inflammatory, and antihyperalgesic also demonstrated therapeutic potential in the treatment of FM. Nevertheless, physicochemical limitations as high volatilization and poor water-solubility make its use difficult. In this perspective, this present research had performed the incorporation of LIN into polymeric nanocapsules (LIN-NC). Size, morphology, encapsulation efficiency, cytotoxicity, and drug release were performed. The antihyperalgesic effect of LIN-NC was evaluated by a chronic non-inflammatory muscle pain model. The results demonstrated that the polymeric nanocapsules showed particle size of 199.1 ± 0.7 nm with a PDI measurement of 0.13 ± 0.01. The drug content and encapsulation efficiency were 13.78 ± 0.05 mg/mL and 80.98 ± 0.003%, respectively. The formulation did not show cytotoxicity on J774 macrophages. The oral treatment with LIN-NC and free-LIN increased the mechanical withdrawal threshold on all days of treatment in comparison with the control group. In conclusion, LIN-NC is a promising proposal in the development of phytotherapy-based nanoformulations for future clinical applications.