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Relationship Between Neurotransmitter Receptor Polymorphisms, Plasma Concentrations and Clinical Response to Clozapine

This study has been completed.
Information provided by (Responsible Party):
Delwyn D. Miller, University of Iowa Identifier:
First received: December 19, 2007
Last updated: May 11, 2017
Last verified: May 2017
This is a study designed to identify genetic polymorphisms (also called allelic variants or genetic markers) that are associated with response to clozapine. This information will be used to enhance the understanding of clozapine response and side effects. DNA from patients will be examined for significant associations between allelic variants in candidate genes in relation to clozapine effects on positive and negative symptoms, global response, quality of life, relapse rates and side effects.


Study Type: Observational
Study Design: Observational Model: Cohort
Time Perspective: Prospective
Official Title: Relationship Between Neurotransmitter Receptor Polymorphisms, Plasma Concentrations and Clinical Response to Clozapine

Resource links provided by NLM:

Further study details as provided by University of Iowa:

Primary Outcome Measures:
  • Brief Psychiatric Rating Scale [ Time Frame: entry, 3 wks, 5 wks, 8 wks, 4 mo, 6 mo ]

Secondary Outcome Measures:
  • Scale for the Assessment of Positive Symptoms [ Time Frame: entry, wk 3, wk 5, wk 8, 4 mo, 6 mo ]
  • Scale for the assessment of Negative symptoms [ Time Frame: entry, 3 wk, 5 wk, 8 wk, 4 mo, 6 mo ]
  • Calgary Depression Scale [ Time Frame: entry, 3 wk, 5 wk, 8 wk, 4 mo, 6 mo ]
  • Abnormal Involuntary Movement Scale [ Time Frame: entry, 3 wk, 5 wk, 8 wk, 4 mo, 6 mo ]
  • Barnes Akathisia Scale [ Time Frame: entry, 3 wk, 5 wk, 8 wk, 4 mo, 6 mo ]

Biospecimen Retention:   Samples With DNA
whole blood, saliva

Enrollment: 76
Study Start Date: October 2001
Study Completion Date: December 2015
Primary Completion Date: December 2015 (Final data collection date for primary outcome measure)
One group, all subjects with DSM-IV diagnosis of Schizophrenia, age 18-65 who are initiating clozapine therapy.

Detailed Description:
Patients age 18-65 with a DSM IV diagnosis of schizophrenia who have a history of nonresponse to conventional atypical antipsychotics and who are to be treated with clozapine by their psychiatrist, will be asked to participate at or near the time clozapine therapy is initiated. The Brief Psychiatric Rating Scale (BPRS), Scale for the Assessment of Negative Symptoms (SANS), and the Scale for the Assessment of Positive Symptoms (SAPS) will be performed on all subjects at entry into the study, at 3 weeks, 5 weeks, 8 weeks, and at 4 and 6 months. Adverse effects will be monitored with the Simpson-Angus Scale, Barnes Akathisia scale and the AIMS at each of these time points. The Calgary Depression Scale will also be administered at each visit. A complete neurocognitive assessment battery will be completed at entry and at 6 months for those subjects willing to undergo neurocognitive testing. It is anticipated not all subjects will complete neurocognitive testing. A blood or cheek swab sample will be collected at study entry for DNA analysis. Plasma blood levels will be collected at weeks 3, 5, 8 and study completion for measurement of clozapine plasma concentrations. The subject's weight, BMI, smoking status and concomitant medications will be recorded at each visit.

Ages Eligible for Study:   18 Years to 65 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population
Psychiatric clinic, Inpatient Psychiatry unit

Inclusion Criteria:

  • Diagnosis of schizophrenia
  • Beginning clozapine therapy
  • age 18-65
  • must be willing to participate in interviews and provide a DNA sample

Exclusion Criteria:

  • no longer taking clozapine
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00581932

United States, Iowa
University of Iowa Hospitals and Clinics
Iowa City, Iowa, United States, 52242
Sponsors and Collaborators
Delwyn D. Miller
Principal Investigator: Del D Miller, PharmD, M.D. The University of Iowa
  More Information

Responsible Party: Delwyn D. Miller, Professor, University of Iowa Identifier: NCT00581932     History of Changes
Other Study ID Numbers: 199901018
Study First Received: December 19, 2007
Last Updated: May 11, 2017

Keywords provided by University of Iowa:
clozapine, schizophrenia

Additional relevant MeSH terms:
Schizophrenia Spectrum and Other Psychotic Disorders
Mental Disorders
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action
Physiological Effects of Drugs
Serotonin Antagonists
Serotonin Agents
Antipsychotic Agents
Tranquilizing Agents
Central Nervous System Depressants
Psychotropic Drugs
GABA Antagonists
GABA Agents processed this record on May 23, 2017