Oral scopolamine augmentation in moderate to severe major depressive disorder: A randomized, double-blind, placebo-controlled study

Objective: To evaluate the antidepressant effect of oral scopolamine as an adjunct to citalopram. Method: In this randomized double-blind placebo-controlled study, patients were assessed in the outpatient clinics of 2 large hospitals from November 2011 to January 2012. Forty patients (18-55 years) with major depressive disorder (DSM-IV-TR criteria) and 17-Item Hamilton Depression Rating Scale (HDRS) score ≥ 22 were randomly assigned to scopolamine hydrobromide (1 mg/d) (n = 20) or placebo (n = 20) in addition to citalopram for 6 weeks. HDRS score was measured at baseline and days 4, 7, 14, 28, and 42. The primary outcome measure was HDRS score change from baseline to week 6 in the scopolamine group versus the placebo group. Response was defined as ≥ 50% decrease in HDRS score; remission, as HDRS score ≤ 7. Results: Augmentation with scopolamine was significantly more effective than placebo (F_1,38 = 5.831, P = .021). Patients receiving scopolamine showed higher rates of response (65%, 13/20 at week 4) and remission (65%, 13/20 at week 6) than the placebo group (30%, 6/20 and 20%, 4/20, respectively; P = .027, P = .004, respectively). Patients in the scopolamine group showed higher rates of dry mouth, blurred vision, and dizziness than the placebo group. Conclusions: Oral scopolamine is a safe and effective adjunct for treatment of patients with moderate to severe major depressive disorder. Trial Registration: Iranian Registry of Clinical Trials identifier: IRCT201201181556N31.