SRIs are considered first-line treatments for obsessive-compulsive disorder, (OCD); however, many patients continue to have significant symptoms despite an adequate trial of an SRI. Neuroimaging studies have shown that  the glutamate neurological system is involved in OCD. This study will test the safety and efficacy of topiramate, a drug, which targets glutamate, in the treatment of OCD, where the OCD has been un-responsive, or partially responsive to regular SRI treatment. The patients will be randomized in a double-blind fashion to the addition of topiramate (Topomax) or placebo to the regular dose of SRI. At the end of the study, participants will enter follow-up care with the study doctor.

McMaster University Medical Centre
Principal Investigator
Michael Van Ameringen, MD
Eligibility Criteria
  • Male or female outpatients 18 years or older with a primary diagnosis of obsessive compulsive disorder, who are currently being treated with an SRI (eg. paroxetine, fluoxetine, fluvoxamine, clomipramine, sertraline, citalopram, escitalopram) or SNRI (venlafaxine, desvenlafaxine, duloxetine) and continue to have OCD symptoms.
  • Physical examination, electrocardiogram, and laboratory findings without clinically significant abnormalities.
  • Willingness and ability to comply with the requirements of the study protocol.
  • Those taking psychotrophic medications, other than an SRI/SNRI are excluded.
The MacAnxiety Research Centre, 905-921-7644 or e-mail
Hamilton, ON