[Penetration capacity and local anti-inflammatory effect of a methyl salicylate gel with turpentine essence, camphor, and menthol for the symptomatic local treatment of muscular and joint pains].

Introduction: Oral non-steroidal anti-inflammatory drugs (NSAIDs) are effective in managing musculoskeletal pain, but often are associated with side effects. Therefore, topical anti-inflammatory drugs are considered a suitable alternative for certain patients. Objective: To determine the skin penetration capacity and anti-inflammatory efficacy of a methyl salicylate gel (MS) with turpentine essence, camphor and menthol (GelSMETAM). Methods: Human skin explants were used (three biological replicates with 3 technical replicates each were performed). To assess penetration capacity, methyl salicylate (MS) levels were quantified at different intervals using liquid chromatography with tandem mass spectrometry (LC-MS/MS). For the anti-inflammatory effect, the gene expression of major pro-inflammatory factors was quantified 30 minutes, 8 hours, and 12 hours after an impact; comparing GelSMETAM application with untreated controls. Results: The results showed that approximately 0.8% of the total applied methyl salicylate penetrated the skin with a time-dependent concentration increase. The anti-inflammatory effect demonstrated a significant reduction in the gene expression of TNFα, IL1α, IL6, IL8, and NFKβ at 30 minutes (between -39% and -53.6% compared to control), which was maintained at 8 hours except for TNFα (between -59% and -92.6%) and persisted even at 12 hours (-69.4%) for IL1α. Conclusion: The results support the hypothesis that GelSMETAM provides an effective and prolonged anti-inflammatory response, positioning it as a suitable option for the management of musculoskeletal pain.