Pariwatcharakul P.Prachgosin P.Mahidol University2026-03-272026-03-272026-01-01Therapeutic Advances in Psychopharmacology Vol.16 (2026)20451253https://repository.li.mahidol.ac.th/handle/123456789/115841This case report describes the rapid clinical response to etifoxine, an oral translocator protein 18 kDa (TSPO) ligand, in a patient with severe, treatment-resistant obsessive-compulsive disorder (OCD) with comorbid bipolar I disorder. Despite extensive prior pharmacological treatments and neurosurgical interventions, the patient experienced significant symptom amelioration within days of etifoxine initiation (the Yale-Brown Obsessive-Compulsive Scale (YBOCS) score decreased from 50 to 29). We discussed the potential mechanisms underlying this rapid response, including direct γ-aminobutyric acid (GABA) receptor modulation, increased endogenous neurosteroidogenesis, reduced neuroinflammation, and modulation of the gut-brain axis. This case highlights etifoxine as a novel therapeutic option for treatment-resistant OCD and underscores the need for further research into TSPO ligands in this context.MedicineArticleSCOPUS10.1177/204512532614299682-s2.0-10503299445620451261