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Completed

NCT Number: NCT03525002

Dopamine Action on Metabolism in Relation to Genotype

Obesity is a widespread disease with increasing prevalence and associated with serious secondary complications. So far, the origin of the disease, regardless of an existing positive energy balance, is not fully understood. In addition to environmental factors, the genetic background plays an important role in the pathogenesis of obesity. Of common genetic polymorphisms, variants in the fat mass and obesity associated gene (FTO) locus have the highest effect size on body weight. Animal and first clinical studies indicate that FTO variants interact with dopamine signaling in the brain, thus influencing the risk of overweight. In fact, preliminary results indicate that enhancing dopamine signaling with the dopamine agonist bromocriptine, depending on the FTO genotype, either induces weight loss or has a neutral effect on body weight.

The planned clinical trial serves to develop a genotype-specific and thus individualized therapy approach for obesity. The influence of dopamine agonist therapy on weight loss as a function of the FTO (rs8050136) genotype is to be tested.

Here, the greatest weight loss is expected to occur in subjects carrying the homozygous risk-allele (AA).

So far, there are only a few established conservative therapy forms of obesity, so that bariatric interventions with an increasing rate are necessary to achieve weight loss and thus a reduction in overall morbidity and mortality. Among the approved drug therapies for obesity, bromocriptine is commonly used. In addition, some interventions require injections. An early, conservative individualized, genotype-specific treatment with little side-effects would enable simple treatment of obesity.

Study design: 150 obese (BMI > 30) subjects (50 / study center) will be enrolled in the study. The subjects will be stratified according to their FTO genotype (rs8050136). Subjects will be randomized into placebo or bromocriptine treatment group. Treatment will last for 18 weeks and a follow-up will be performed 30 weeks after baseline.

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Key information

Conditions

Obesity Body Weight Nutrition Disorders Nutritional and Metabolic Diseases Overnutrition Overweight Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2

Primary location

University Hospital Cologne, Cologne, Germany

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Body mass index (BMI) between >30 kg/m².
  • Understand and voluntarily sign an informed consent document prior to any study related assessments/procedures.
  • Females of childbearing potential (FCBP) must agree to utilize a reliable form of contraception simultaneously or practice complete abstinence from heterosexual contact while participating in the study.
  • Males must agree to use a latex condom during any heterosexual contact while participating in the study and to refrain from donating semen or sperm while participating in this study.

Exclusion criteria

  • Women during pregnancy and lactation.
  • History of hypersensitivity to the investigational medicinal product or to any drug with similar chemical structure or to any excipient present in the pharmaceutical form of the investigational medicinal products.
  • Participation in other clinical trials or observation period of competing trials up to 30 days prior to this study.
  • Diabetes mellitus
  • Treatment with Methyldopa, levodopa, dopamine agonists, metoclopramid, domperidon, glycerol nitrate, griseofulvin, azol-antimycotic drugs, macrolide-antibiotics, octreotide, orlistat, tamoxifen, liraglutide
  • Any relevant cardiovascular disease, e.g. myocardial infarction, acute coronary syndrome, unstable angina pectoris, Percutaneous transluminal coronary angioplasty (PTCA), heart failure (NYHA III-IV), stroke or transient ischemic attack (TIA)
  • Acute or chronic viral hepatitis or liver cirrhosis
  • Impaired renal function, defined as estimated Glomerular Filtration Rate (eGFR) ≤ 60 ml/min (MDRD formula) as determined during screening.
  • Medical history of cancer and/or treatment for cancer within the last 5 years.
  • Claustrophobia
  • Any other clinically significant major organ system disease at screening such as relevant gastrointestinal, neurologic, psychiatric, endocrine (i.e. pancreatic), hematologic, malignant, infection or other major systemic diseases making implementation of the protocol or interpretation of the study results difficult.
  • Presence of any contraindication for the conduct of an MRI investigation, such as cardiac pacemakers, ferromagnetic haemostatic clips in the central nervous system, metallic splinters in the eye, ferromagnetic or electronically operated active devices like automatic cardioverter defibrillators, cochlear implants, insulin pumps and nerve stimulators, prosthetic heart valves etc.
  • hyperthyroidism
  • therapy refractary hypertension
  • peripheral arterial disease
  • Parkinson´s disease
  • Known current presence or history of one of the following psychiatric diseases: depression, mania, anxiety and panic disorder, obsessive-compulsive disorder, schizophrenia, psychosis, addiction
  • pituitary disease
  • treatment with bromocriptine during 12 month before entering the trial
  • dementia
  • gastric or intestinal ulcer
  • Persons with limited temperature sensation and / or elevated sensitivity to warming of the body
  • Persons with a hearing disorder or a increased sensitivity for loud noises
  • smoking
  • Refusal to get informed of unexpected detected pathological findings

Any other clinical condition that would jeopardize subjects' safety while participating in this clinical trial.

Treatment and study plan

Bromocriptine

Drug

In each FTO genotype group participants will be randomly receive bromocriptine or placebo.

Placebo

Other

In each FTO genotype group participants will be randomly receive bromocriptine or placebo.

Primary outcomes

  1. Interaction between FTO genotype and treatment on change in body weight.

    Time frame: 18 weeks

    Interaction between FTO (single nucleotide peptide) SNP rs8050136 genotype and treatment (bromocriptine or placebo) on change in body weight.

Secondary outcomes

  1. Effect of bromocriptine vs. placebo on body weight

    Time frame: 18 weeks

  2. Effect of bromocriptine vs. placebo on dietary intake

    Time frame: 18 weeks

    Dietary intake will be monitored by food diaries

  3. Effect of bromocriptine vs. placebo on processing of food cues in the brain

    Time frame: 18 weeks

    Processing of food cues in the brain will be assessed by functional magnetic resonance imaging before and after treatment with bromocriptine or placebo

  4. Effect of bromocriptine vs. placebo on body fat distribution

    Time frame: 18 weeks

    Body fat distribution will be assessed by magnetic resonance imaging and magnetic resonance spectroscopy before and after treatment with bromocriptine or placebo

  5. Effect of bromocriptine vs. placebo on whole body insulin sensitivity

    Time frame: 18 weeks

    Whole body insulin sensitivity will be quantified from 5 point 75g oral glucose tolerance test before and after treatment with bromocriptine or placebo

  6. Effect of bromocriptine vs. placebo on insulin secretion

    Time frame: 18 weeks

    Insulin secretion will be quantified from 5 point 75g oral glucose tolerance test before and after treatment with bromocriptine or placebo

  7. Effect of bromocriptine vs. placebo on glucose tolerance

    Time frame: 18 weeks

    Glucose tolerance will be assessed by 75g oral glucose tolerance test before and after treatment with bromocriptine or placebo

  8. Effect of bromocriptine vs. placebo on brain insulin sensitivity

    Time frame: 18 weeks

    Brain insulin sensitivity will be assessed by functional magnetic resonance imaging combined with intranasal insulin administration before and after treatment with bromocriptine or placebo

  9. Effect of bromocriptine vs. placebo on resting energy expenditure

    Time frame: 18 weeks

    Resting energy expenditure will be assessed by indirect calorimetry before and after treatment with bromocriptine or placebo

  10. Effect of bromocriptine vs. placebo on physical activity

    Time frame: 18 weeks

    Physical activity will be monitored using an accelerometer

  11. Effect of bromocriptine vs. placebo on serum prolactin concentrations

    Time frame: 18 weeks

Sponsors and collaborators

Lead sponsor

University Hospital Tuebingen

Other

Collaborators

  • University Hospital Lübeck
  • University Hospital of Cologne

Registry information

Official study title

Dopamine Action on Metabolism Depending on Genetic Heterogeneity - a Randomized, Placebo-controlled Double Blind Study

Important dates

Study start
2018
Primary completion
2024
Study completion
2024
First posted
May 15, 2018
Registry last updated
Nov 24, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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