Intravenous clomipramine challenge in obsessive-compulsive disorder: Predicting response to oral therapy at eight weeks

Background: Challenge with intravenous clomipramine (CMI) is serotonin selective and has been reported to transiently exacerbate symptoms in obsessive-compulsive disorder (OCD) patients, and to predict subsequent response to oral CMI therapy. Methods: We administered CMI (12.5 mg, IV) to medi- cation free OCD patients (N = 29) and normal controls (N = 22) to characterize neurohormonal response. A subset of OCD patients (26/29), was then treated with either pulse load IV or oral CMI followed by 8 weeks of oral CMI therapy. Results: In response to CMI challenge, OCD patients exhibit blunted cortisol and exaggerated growth hormone response relative to normal controls. OCD patients differ from controls in 'sadness' ratings, with controls exhibiting increased dysphoria in response to CMI. Growth hormone response to CMI challenge predicts treatment response (≤ 25% ↓ YBOCS from baseline) to oral CMI at 8 weeks. Conclusions: Growth hormone abnormalities associated with OCD in response to CMI challenge differentiates nonresponders after 8 weeks of oral CMI treatment from responders.