Ondansetron in Treatment Resistant Obsessive Compulsive Disorder (OCD)

METHOD: Fourteen patients with a DSM-IV diagnosis of treatment resistant OCD, under stable treatment with SSRI's and neuroleptic augmentation will enter an 12-week single blind trial of ondansetron initiated at a dose of 0.25 mg twice daily for 6 weeks, that will be titrated to 0.5 mg twice daily for 6 weeks.

Inclusion criteria

• adults aged 18 to 55
• a Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) score of ≥ 20 after ≥ 12 weeks of treatment with an established effective dose of an Selective Serotonin Reuptake Inhibitors or clomipramine and after ≥ 10 weeks of augmentation treatment with antipsychotics (risperidone at least 2 mg/day quetiapine at least 150 mg/day; olanzapine at least 5mg/day; haloperidol titrated at least 10 mg/day; aripiprazole at least 10 mg/day)

Exclusion criteria

• a history of alcohol or substance abuse
• current severe depressive symptoms, bipolar disorder, panic disorder, schizophrenia, or other psychiatric conditions
• heart disease, arrhythmia, liver problems, including cirrhosis, seizures, glaucoma or serious medical disease
• hoarding as only Obsessive Compulsive symptom
• women of childbearing potential not using a medically acceptable contraceptive method.