Effects of Ondansetron in Obsessive-compulsive and Tic Disorders
Condition: Obsessive-Compulsive Disorder; Tic Disorders; Tourette Syndrome
MeSH terms: Tourette Syndrome; Tics; Tic Disorders; Compulsive Personality Disorder; Obsessive-Compulsive Disorder
Intervention: Ondansetron; Placebo
Intervention description: 5-HT3 (serotonin receptor type 3) antagonist commonly used to treat nausea and vomiting; placebo equivalent
Intervention MeSH terms: Ondansetron
Phase: Phase 4
Study type: Interventional
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Enrollment: 110.0
Sex: All
Minimum age: 18 Years
Maximum age: 60 Years
Healthy volunteers: No
Keywords: Brain Function; functional magnetic resonance imaging (fMRI); Sensory processing; Obsessive-Compulsive Disorder; OCD

Summary:

      This project investigates the use of 4 weeks of 24 mg/day ondansetron as compared to placebo
      on symptoms and brain functioning in patients with obsessive-compulsive disorder (OCD) and
      tic disorders (TD). Patients will be randomized to receive ondansetron or placebo for 4
      weeks, with MRI scans and symptom assessments occurring at baseline (before any drug) and at
      the end of the 4 weeks. Patients will also be asked to come into the lab approximately 2
      weeks into the trial for symptom assessments. The investigators hypothesize that after 4
      weeks there will be greater reduction from baseline in sensory symptoms and the activation of
      the insula and sensorimotor cortex compared for ondansetron as compared to placebo.
    

Eligibility criteria:

        Inclusion Criteria:

          -  Patients must be medically healthy, between 18 and 60 years of age

          -  Fluent (speaking and writing) in English

          -  Patients must have a current diagnosis of obsessive-compulsive disorder (OCD) or tic
             disorder (OCD) according to Diagnostic and Statistical Manual of Mental Disorders
             (DSM-5) criteria with moderate or greater disorder severity and moderate or greater
             severity of sensory phenomena

          -  Patients must be unmedicated or taking antidepressants, stable for at least 6 weeks

        Exclusion Criteria:

          -  Present or previous diagnosis of any psychosis, bipolar disorder, or major
             developmental disorder (autism/Asperger's disorder, pervasive developmental disorder).
             Present diagnosis of alcohol or substance use disorder (moderate or severe) will also
             be exclusionary.

          -  Any disability or health problem that prevents them from completing study procedures
             (e.g. color blindness, severe carpal tunnel syndrome, etc.).

          -  History of organic mental syndromes, head trauma, migraines, seizures, other central
             nervous system (CNS) neurological disease, or significant medical illness other than
             that listed above.

          -  Pregnant or nursing women will be excluded.

          -  Subjects with a medical condition or other predisposition that increases the risk of
             adverse effects when taking ondansetron. These include, but are not limited to,
             individuals with drug allergies or known hypersensitivity to ondansetron (or other
             5-HT3 antagonists), heart disease, congestive heart failure, heart rhythm disorder,
             congenital long QT syndrome, electrolyte abnormalities (e.g., hypokalemia,
             hypomagnesemia) or hepatic impairment.

          -  Subjects who report taking apomorphine will be excluded.

          -  Subjects with abnormal EKG will either be excluded from participation, or referred to
             a cardiologist for further assessment of eligibility.

          -  Subjects with abnormal liver function or electrolytes (as determined by blood test)
             will be excluded from participation if a study team physician determines it is unsafe
             for them to participate.

          -  Cross-reactivity with other 5-HT3 antagonists has been reported, so any individual
             taking a 5-HT3 antagonist will be excluded.