NCT06866444 · University of Utah
Duloxetine Metabolism and Fibromyalgia
(DILIGENT)
What this study is about
People with fibromyalgia report generalized body pain ("pain all over"), increased sensitivity to painful stimulation, chronic tiredness or low energy, sleep problems, and other physical and functional problems. The exact cause of the disorder is poorly understood, and treatment can be difficult. The degree to which duloxetine is helpful for people with fibromyalgia varies greatly.
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People with fibromyalgia report generalized body pain ("pain all over"), increased sensitivity to painful stimulation, chronic tiredness or low energy, sleep problems, and other physical and functional problems. The exact cause of the disorder is poorly understood, and treatment can be difficult. The degree to which duloxetine is helpful for people with fibromyalgia varies greatly. For some people, it is very helpful for managing fibromyalgia symptoms. For others, people may not notice any benefit. Yet for some, it is a little helpful and the effect is noticeable only when people forget to take the medicine. The purpose of this study is to collect data to better understand the relationship among gene types that control those enzymes, blood concentrations of duloxetine, and how it helps the symptoms.
Interventions
DRUG
Observational
In a cohort of patients treated with duloxetine for fibromyalgia, participants vitals signs (blood pressure, heart rate, oxygen saturation level, temperature) will be taken as well as height and weight. Participants will fill out a questionnaire regarding their fibromyalgia diagnosis and symptoms. Lastly, participants will complete two sets of blood samples. One blood sample will evaluate genetic variants for duloxetine metabolizing capacity. The other sample will be used to analyze the level of concentration of duloxetine.
Primary outcome measures
Duloxetine concentrations across metabolizer phenotypes, 3 groups
Time frame: Obtained four hours after morning duloxetine dose.
Metabolizer phenotypes will be separated into 3 groups based on diplotypes. Ultrarapid metabolizer phenotypes will be measured by having an activity score of greater than 2.0. Normal/intermediate metabolizer phenotypes will be measured by having an activity score between 1.0 to 2.0. Slow metabolizer phenotypes will be measured by having an activity score between 0.75 to 0.
Measure inhibitors and inducers of CYP1A2 and CYP2D6 in blood sample
Time frame: Obtained four hours after the morning duloxetine dose.
Inhibitors and inducers of CYP1A2 and CYP2D6 are defined by the Drug Interaction Flockhart Table. A strong inhibitor will be measured by ≥ 5-fold increase in plasma AUC or more than 80% decrease in clearance. A moderate inhibitor will be measured by 2 to 5-fold increase in the plasma AUC or 50-80% decrease in clearance.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Meeting diagnostic criteria for Fibromyalgia
- Patients taking Duloxetine 60 mg/day for at least 8 weeks
Exclusion criteria
- Pregnant patients per verbal confirmation
- Patients that have a history of physician diagnosed kidney or liver disfunction or history of renal dialysis.
- Patients requiring an interpreter to communicate
- Patient's with progressive illnesses other than fibromyalgia that have a chronic pain and fatigue component (e.g., cancer patients receiving antineoplastic treatment, Parkinson's disease, Multiple Sclerosis).
Where
- Salt Lake City, Utah
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Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Aug 21, 2025 · Source of record for eligibility and locations