A rapid clinical response to etifoxine in treatment-resistant obsessive-compulsive disorder: a case report of a patient with comorbid bipolar disorder.

This 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.