Amantadine as adjuvant therapy in the treatment of moderate to severe obsessive-compulsive disorder: A double-blind randomized trial with placebo control

Aim The role of the glutamatergic system in the pathogenesis of obsessive-compulsive disorder (OCD) has been shown by numerous studies. The aim of the present randomized, double-blind, placebo-controlled, 12-week trial was to assess the efficacy and tolerability of amantadine as an adjuvant to fluvoxamine in the treatment of patients with moderate to severe OCD. Methods One hundred patients diagnosed with moderate to severe OCD were randomized into two parallel groups to receive fluvoxamine (100 mg twice a day) plus placebo or fluvoxamine (100 mg twice a day) plus amantadine (100 mg daily) for 12 weeks. All patients received 100 mg/day fluvoxamine for 28 days followed by 200 mg/day for the rest of the trial, regardless of their treatment groups. Patients were evaluated for response to treatment using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) at baseline and at Weeks 4, 10, and 12. The main outcome measure was to assess the efficacy of amantadine in improving the OCD symptoms. Results Repeated-measure analysis of variance showed a significant effect for Time x Treatment interaction (Greenhouse-Geisser corrected: F = 3.84, d.f. = 1.50, P = 0.03) in the Y-BOCS total score and a significant effect for Time x Treatment interaction (Greenhouse-Geisser corrected: F = 5.67, d.f. = 1.48, P < 0.01) in the Y-BOCS Obsession subscale score between the two groups. Conclusion The results of this study suggest that amantadine may be effective as an augmentative agent in the treatment of moderate-to-severe OCD.