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Effectiveness of Pimozide in Augmenting the Effects of Clozapine in the Treatment of Schizophrenia

Information source: Icahn School of Medicine at Mount Sinai
ClinicalTrials.gov processed this data on August 23, 2015
Link to the current ClinicalTrials.gov record.

Condition(s) targeted: Schizophrenia; Psychotic Disorders

Intervention: Pimozide (Drug); Placebo (Drug)

Phase: Phase 4

Status: Completed

Sponsored by: Icahn School of Medicine at Mount Sinai

Official(s) and/or principal investigator(s):
Joseph I. Friedman, MD, Principal Investigator, Affiliation: Icahn School of Medicine at Mount Sinai


This study will assess the effectiveness of pimozide in enhancing the effects of clozapine in the treatment of schizophrenia.

Clinical Details

Official title: Pimozide Augmentation of Clozapine in Schizophrenia

Study design: Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor), Primary Purpose: Treatment

Primary outcome:

Positive Syndrome Scale (PANSS) Total Score

Negative Syndrome Scale (PANSS) Total Score

Secondary outcome: Clinical Global Impression of Change (CGIC)

Detailed description: A significant number of schizophrenics exhibit partial or no response to typical antipsychotic medications. Clozapine has been shown to be more effective in treating schizophrenia than typical antipsychotic drugs. However, only an estimated 30% to 60% of people who are unresponsive to treatment with typical antipsychotics will respond to treatment with clozapine. Taking clozapine with pimozide, an antipsychotic drug, can increase clozapine's effects. However, sufficient research on this approach has not yet been performed. This study will assess the effectiveness of pimozide in enhancing the effects of clozapine in the treatment of schizophrenia. Participants in this double-blind study will receive a stable dose of clozapine for eight weeks prior to enrollment. For the first 4 weeks following enrollment, baseline measurements will be taken. Once a week, participants will report to the study site, where symptom severity, cognitive ability, and functional status, including reading level, will be assessed. In addition, participants will receive a standard medical examination, which will include blood tests and an EKG. Upon completion of this initial phase, participants will be randomly assigned to one of two treatment groups: clozapine combined with pimozide; or clozapine combined with placebo. This phase will last for 12 weeks. Study visits will continue to occur weekly, and will be used to re-assess the measurements obtained during baseline. In addition, participants will have an EKG at each study visit for the first 4 weeks of treatment. All baseline measurements will be repeated in Week 12.


Minimum age: 18 Years. Maximum age: 65 Years. Gender(s): Both.


Inclusion Criteria:

- Diagnosis of schizophrenia according to DSM-IV criteria

- Any schizoaffective disorder or subtype

- Score greater than 60 on the Positive and Negative Syndrome Scale (PANSS)

- Currently taking clozapine

- Score of four or higher on two or more items from the positive symptom subscale of


- Score of 4 or greater on the Clinical Global Impression (CGI) scale

- Clozapine plasma level greater than 378 µg/ml

- Stable dose of clozapine demonstrated to have been associated with a clozapine plasma

level greater than 378 µg/ml for at least eight weeks

- Able to read at an 8th grade level or above

Exclusion Criteria:

- History of unstable coronary artery disease

- Congestive heart failure

- History of long Q-T syndrome

- History of cardiac arrhythmia

- History of cardiac conduction delay

- Baseline QT correction score greater than 0. 425 seconds

- Liver disease

- History of stroke

- History of Neuroleptic Malignant Syndrome

- Hypokalemia

- Hypocalcemia

- Current blindness, deafness, language difficulties, or any other disability which may

prevent participation or cooperation in the study

- Current suicidal or homicidal thoughts

- Currently abusing psychoactive substances

- Currently receiving antidepressants, thymoleptics, L-DOPA, buspirone, or

antipsychotics other than clozapine (Valproic acid and Divalproex sodium are not criteria for exclusion)

Locations and Contacts

Icahn School of Medicine at Mount Sinai, New York, New York 10029, United States

Manhattan Psychiatric Center, New York, New York 10035, United States

Pilgrim Psychiatric Center, W. Brentwood, New York 11717, United States

Additional Information

Related publications:

Friedman J, Ault K, Powchik P. Pimozide augmentation for the treatment of schizophrenic patients who are partial responders to clozapine. Biol Psychiatry. 1997 Sep 15;42(6):522-3.

Starting date: October 2004
Last updated: April 7, 2015

Page last updated: August 23, 2015

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