FibromyalgiaDILIGENTNCT06866444
Duloxetine Metabolism and Fibromyalgia
An observational study of Fibromyalgia and Duloxetine, run by University of Utah at 1 site in United States.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Fibromyalgia, Duloxetine
- What is being tested?
- Observational
- How many people
- 100 participants
- Where
- 1 siteUnited States
- Study dates
- 1 May 2025to 1 May 2027
- How long will I take part?
- 12 Months
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Patients treated at the Pain Management Center (PMC) at the University of Utah who meet inclusion criteria.
Who may be able to join
- Adults 18+
- Meeting diagnostic criteria for Fibromyalgia
- Patients taking Duloxetine 60 mg/day for at least 8 weeks
Who cannot join
- 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).
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Pain Management Center and Pain Research Center at the University of Utah
Salt Lake City, Utah, 84132
Jake Steenblick, DNP, 801-585-1216, jacob.steenblik@nurs.utah.edu
About this study
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.
Read the detailed description
Study Purpose: To study the variability of response in patients with fibromyalgia to treatment with duloxetine
Duloxetine is a common FDA-approved pharmacotherapy for fibromyalgia. However, there is significant treatment response variability. Prior work has explored the role of liver drug-metabolizing enzymes CYP2D6 and CYP1A2 in the biotransformation of duloxetine. The genes coding for these enzymes have many variants; some variants are rapid metabolizers, whereas others are slow metabolizers of duloxetine. The different variants may contribute to the wide range of treatment responses to duloxetine among fibromyalgia patients. Supporting duloxetine metabolism as a contributor to drug response variability, researchers have measured plasma duloxetine concentrations following recommended dosing regimens and found concentrations to have substantial variability.
A strong correlation between an ultra-rapid duloxetine metabolizer with a poor response to duloxetine will provide useful information when formulating a treatment plan. Patients with a poor response to duloxetine phenotype may be better served by another serotonin norepinephrine reuptake inhibitor such as milnacipran. Early identification of those who would benefit from duloxetine will help a personalized approach to treating fibromyalgia and optimize the cost-effectiveness of pharmacological interventions.
Drug interactions with duloxetine that influence drug effect: An important consideration in characterizing duloxetine metabolism is to account for drug interactions that may inhibit or induce CYP1A2 or CYP2D6.
The main objective of this proposal is to conduct a feasibility study/pilot study to serve as the basis for a larger study where we refine our study methodology. In a cohort of patients treated with duloxetine for fibromyalgia, this study will measure:
(i) Symptoms of fibromyalgia using a validated questionnaire.
(ii) Duloxetine plasma concentrations.
(iii) Genotype CYP2D6 and CYP1A2 and correlate their plasma concentrations and genotype (rapid, normal, or slow metabolizer) with fibromyalgia symptoms.
Hypotheses:
(i) Patients with rapid or slow metabolizing variants will have low and high duloxetine plasma concentrations respectively.
(ii) Patients with rapid metabolizing variants will have ineffective treatment with duloxetine and patients with slow metabolizing variants will have signs and symptoms of effective treatment or duloxetine toxicity.
(iii) Patients who consume inducers or inhibitors of CYP2D6 or CYP1A2 will have low and high duloxetine plasma concentrations, respectively. Patients who consume inducers of CYP2D6 or CYP1A2 will have ineffective treatment with duloxetine, and patients that consume inhibitors of CYP2D6 or CYP1A2 will have signs and symptoms of effective treatment or duloxetine toxicity.
- Conditions
- Fibromyalgia, Duloxetine
- Being tested
- Observational
- Keywords
- Duloxetine, Duloxetine metabolism
- Medical subject headings
- Fibromyalgia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
ObservationalDrug
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.
| Study group | Role | What they receive |
|---|---|---|
| Adult patients treated with duloxetine for fibromyalgia | Adults 18+
Meeting diagnostic criteria for Fibromyalgia
Patients taking Duloxetine 60 mg/day for at least 8 weeks Receives: Drug: Observational |
What is being measured
The primary outcome is the main question the study is designed to answer.
Duloxetine concentrations across metabolizer phenotypes, 3 groups
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.
Measured: Obtained four hours after morning duloxetine dose.
Measure inhibitors and inducers of CYP1A2 and CYP2D6 in blood sample
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.
Measured: Obtained four hours after the morning duloxetine dose.
Secondary outcomes (6)
Symptoms of fibromyalgia
Measured by the Revised Fibromyalgia Impact Questionaire (FIQR) and ACR 2016 criteria for fibromyalgia. The FIQR is scored on a scale of 0-100, with higher scores (100) indicating a greater impact of fibromyalgia (worst outcome) and lower scores (0) indicating a lesser impact of fibromyalgia (better outcome).
Measured: From start of study visit to end (approximately 2 hours).
Vital signs, heart rate
Heart rate (bpm) will be recorded.
Measured: One time at the start of the study visit.
Vital signs, noninvasive blood pressure
Blood pressure (mmHg) readings will be recorded.
Measured: One time at the start of the study visit.
Vital signs, oxygen hemoglobin saturation
Oxygen hemoglobin saturation (Sp02 using pulse oximeter) will be recorded.
Measured: One time at the start of the study visit.
Vital signs, temperature
Temperature (Celcius) will be recorded.
Measured: One time at the start of the study visit.
Vital signs, respiratory rate
Respiratory rate will be recorded (via observation for 1 minute).
Measured: One time at the start of the study visit.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Mar 2025
- Study start1 May 2025
- Primary completion1 May 2027 (estimated)
- Study completion1 May 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for FibromyalgiaStudies of the same condition, open and under way.
- More trials run by University of UtahThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 100 participants (estimated)
- Target duration
- 12 Months
Sponsor and investigators
- Lead sponsor
- University of Utah
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Jake Steenblik, University of Utah
- Investigators
- Jake Steenblick, DNP, Principal investigator, University of Utah
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06866444
- Sponsor's protocol ID
- IRB_00167537
- Acronym
- DILIGENT
- Status last verified
- Sep 2026
- First submitted
- 4 Mar 2025
- Last updated
- 25 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 25 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Duloxetine Metabolism and Fibromyalgia
- ClinicalTrials.gov ID
- NCT06866444
- Acronym / sponsor ID
- DILIGENT / IRB_00167537
- Conditions
- Fibromyalgia, Duloxetine
- Keywords
- Duloxetine, Duloxetine metabolism
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 100 participants (estimated)
- Lead sponsor
- University of UtahUniversity, hospital or other
- Study start
- 1 May 2025 (actual)
- Primary completion
- 1 May 2027 (estimated)
- Study completion
- 1 May 2027 (estimated)
- First posted
- 10 Mar 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
Study Purpose: To study the variability of response in patients with fibromyalgia to treatment with duloxetine
Duloxetine is a common FDA-approved pharmacotherapy for fibromyalgia. However, there is significant treatment response variability. Prior work has explored the role of liver drug-metabolizing enzymes CYP2D6 and CYP1A2 in the biotransformation of duloxetine. The genes coding for these enzymes have many variants; some variants are rapid metabolizers, whereas others are slow metabolizers of duloxetine. The different variants may contribute to the wide range of treatment responses to duloxetine among fibromyalgia patients. Supporting duloxetine metabolism as a contributor to drug response variability, researchers have measured plasma duloxetine concentrations following recommended dosing regimens and found concentrations to have substantial variability.
A strong correlation between an ultra-rapid duloxetine metabolizer with a poor response to duloxetine will provide useful information when formulating a treatment plan. Patients with a poor response to duloxetine phenotype may be better served by another serotonin norepinephrine reuptake inhibitor such as milnacipran. Early identification of those who would benefit from duloxetine will help a personalized approach to treating fibromyalgia and optimize the cost-effectiveness of pharmacological interventions.
Drug interactions with duloxetine that influence drug effect: An important consideration in characterizing duloxetine metabolism is to account for drug interactions that may inhibit or induce CYP1A2 or CYP2D6.
The main objective of this proposal is to conduct a feasibility study/pilot study to serve as the basis for a larger study where we refine our study methodology. In a cohort of patients treated with duloxetine for fibromyalgia, this study will measure:
(i) Symptoms of fibromyalgia using a validated questionnaire.
(ii) Duloxetine plasma concentrations.
(iii) Genotype CYP2D6 and CYP1A2 and correlate their plasma concentrations and genotype (rapid, normal, or slow metabolizer) with fibromyalgia symptoms.
Hypotheses:
(i) Patients with rapid or slow metabolizing variants will have low and high duloxetine plasma concentrations respectively.
(ii) Patients with rapid metabolizing variants will have ineffective treatment with duloxetine and patients with slow metabolizing variants will have signs and symptoms of effective treatment or duloxetine toxicity.
(iii) Patients who consume inducers or inhibitors of CYP2D6 or CYP1A2 will have low and high duloxetine plasma concentrations, respectively. Patients who consume inducers of CYP2D6 or CYP1A2 will have ineffective treatment with duloxetine, and patients that consume inhibitors of CYP2D6 or CYP1A2 will have signs and symptoms of effective treatment or duloxetine toxicity.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Target follow-up
- 12 Months
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Adult patients treated with duloxetine for fibromyalgia | – | Drug: ObservationalAdults 18+ Meeting diagnostic criteria for Fibromyalgia Patients taking Duloxetine 60 mg/day for at least 8 weeks |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Patients treated at the Pain Management Center (PMC) at the University of Utah who meet inclusion criteria.
Key inclusion criteria (3 listed)
- Adults 18+
- Meeting diagnostic criteria for Fibromyalgia
- Patients taking Duloxetine 60 mg/day for at least 8 weeks
Key exclusion criteria (4 listed)
- 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).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| ObservationalIn 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. | Drug | Adult patients treated with duloxetine for fibromyalgia |
Primary outcome
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.
6 secondary outcomes
Symptoms of fibromyalgia
Time frame: From start of study visit to end (approximately 2 hours).
Vital signs, heart rate
Time frame: One time at the start of the study visit.
Vital signs, noninvasive blood pressure
Time frame: One time at the start of the study visit.
Vital signs, oxygen hemoglobin saturation
Time frame: One time at the start of the study visit.
Vital signs, temperature
Time frame: One time at the start of the study visit.
Vital signs, respiratory rate
Time frame: One time at the start of the study visit.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 25 Sep 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Jake Steenblick, DNP principal investigator
University of Utah
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Fibromyalgia and Duloxetine, run by University of Utah at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 25 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Jake Steenblick, DNP (801-585-1216, jacob.steenblik@nurs.utah.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Duloxetine concentrations across metabolizer phenotypes, 3 groups (time frame: Obtained four hours after morning duloxetine dose.). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 25 Sep 2026.