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Clozapine Induced Weight Gain

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details. Identifier: NCT03996356
Recruitment Status : Not yet recruiting
First Posted : June 24, 2019
Last Update Posted : June 24, 2019
Information provided by (Responsible Party):
Cwm Taf University Health Board (NHS)

Brief Summary:
Clozapine is prescribed to patients with psychosis in whom other treatments have not worked. Research has shown, however, that clozapine may be associated with weight gain and abnormal blood sugar levels in some patients. There is strong evidence to suggest that genetic variation between individuals plays an important role in the development of these side effects in response to the medication. Our research aims to evaluate the effects of two genes and the blood level of clozapine on side-effects such as weight changes and blood sugar levels in patients receiving clozapine treatment. From out-patient clinics in Cwm Taf UHB, the investigators aim to recruit 160 patients who are taking clozapine; collect information/ measurements from recruits relating to size/ weight/ BMI, risk of diabetes and blood samples to measure markers of blood sugar, fat/lipids, clozapine and its breakdown products, blood cells and variants of two specific genes. From this information the investigators will be particularly interested to understand if there is any association between the variation in these two genes with weight gain or changes in blood sugar, in patients taking clozapine.

Condition or disease Intervention/treatment
Weight Gain Antipsychotic Agents Pharmacogenetics Other: No study intervention - observational study

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Study Type : Observational
Estimated Enrollment : 160 participants
Observational Model: Cohort
Time Perspective: Prospective
Official Title: Clozapine Induced Weight Gain: A Pharmacogenetic Study
Estimated Study Start Date : March 2020
Estimated Primary Completion Date : March 2021
Estimated Study Completion Date : October 2021

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Body Weight
Drug Information available for: Clozapine

Intervention Details:
  • Other: No study intervention - observational study
    This is an observational study where the comparative groups will be determined by the genetic variants (SNPs) of subjects and not an intervention, per se.

Primary Outcome Measures :
  1. Body-mass index (BMI) [ Time Frame: 12 months ]
    BMI will be calculated by weight (kg)/ height^2 (m^2).

  2. Leptin gene promoter region single nucleotide polymorphisms (SNPs) (rs7799039) [ Time Frame: 12 months ]
    SNPs will be determined by polymerase chain reaction followed by restriction fragment length polymorphism analysis to determine (c.-2548G or c.-2548A) .

  3. Serotonin 5-HT 2C receptor gene single nucleotide polymorphisms (SNPs) (rs3813929) [ Time Frame: 12 months ]
    SNPs will be determined by polymerase chain reaction followed by restriction fragment length polymorphism analysis to determine (c.-759C or c.-759T) .

Secondary Outcome Measures :
  1. Blood haemoglobin A1c concentration [ Time Frame: 6 months ]
    Haemoglobin A1c concentrations will be determined by ion-exchange HPLC (G8, Tosoh, Amsterdam, Netherlands)

  2. Waist:hip ratio [ Time Frame: 12 months ]
    Waist:hip ratio will be calculated by waist circumference (cm)/hips circumference (cm)

  3. Lipid profile [ Time Frame: 12 months ]
    Serum lipid profiles will include total cholesterol, HDL cholesterol, LDL cholesterol and triglyceride. These will be measured by enzymatic colorimetric methods on cobas-Roche analysers (Roche, Burges Hill, UK) except LDL cholesterol, which will be calculated using the Friedewald equation ([LDL cholesterol] = [Total cholesterol] - ([Triglyceride] / 2.2) - [HDL cholesterol]

  4. Clozapine side effects assessment by Clinical Global Impression (CGI) scale [ Time Frame: 12 months ]
    Clinical Global Impression (CGI) scale is a validated tool to assess clozapine side effects (Ref: Guy W, editor. ECDEU Assessment Manual for Psychopharmacology. 1976. Rockville,MD, U.S. Department of Health, Education, and Welfare)

  5. Clozapine:nor clozapine ratio [ Time Frame: 12 months ]
    Clozapine:nor clozapine ratio is calculated by clozapine (ug/L)/ nor clozapine (ug/L) both measured by high-performance liquid chromatography with diode-array detection.

Biospecimen Retention:   Samples With DNA

4 blood samples to be taken at 0 and 6 months (2x EDTA plasma/whole blood, 2x serum).

Biochemical markers and status of 2 common single nucleotide polymorphisms will be measured.

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Probability Sample
Study Population
Patients on clozapine treatment

Inclusion Criteria:

  • Age 18 years or over
  • Taking/compliant with clozapine antipsychotic medications.
  • Patients meeting the ICD-10 criteria for a diagnosis of schizophrenia, schizoaffective or borderline personality disorders.

Exclusion Criteria:

  • History of current alcohol/illicit substance dependency.
  • Unable/ unsuitable to complete the study protocol e.g. acutely ill, suicidal or aggressive patients.
  • Unable to consent to the study.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT03996356

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Contact: Brian P Tennant, PhD (+44)1685728278
Contact: Rhian Beynon, MSc 01443444500

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United Kingdom
Cwm Taf University Health Board
Merthyr Tydfil, Wales, United Kingdom, CF47 9DT
Contact: Brian P Tennant, PhD    (44)1685728278   
Contact: Rhian Beynon, MSc    01443444500   
Sponsors and Collaborators
Cwm Taf University Health Board (NHS)
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Principal Investigator: Brian P Tennant, PhD Cwm Taf Morgannwg UHB

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Responsible Party: Cwm Taf University Health Board (NHS) Identifier: NCT03996356    
Other Study ID Numbers: CT/688/000000/16
First Posted: June 24, 2019    Key Record Dates
Last Update Posted: June 24, 2019
Last Verified: June 2019

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Additional relevant MeSH terms:
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Body Weight
Weight Gain
Signs and Symptoms
Body Weight Changes