Duloxetine Metabolism and Fibromyalgia

NCT06866444 | Recruiting FDA Drug

• 1 other identifier: IRB_00167537
• Study Type: observational
• Target: 100
• Locations: 1 country
• Sites: 1

Brief 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. 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.

Conditions

Fibromyalgia; Duloxetine

Keywords

Duloxetine; Duloxetine metabolism

Outcome Measures

Primary Outcomes (2)

• 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.

  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.

  Obtained four hours after the morning duloxetine dose.

Secondary Outcomes (6)

• Symptoms of fibromyalgia

  From start of study visit to end (approximately 2 hours).

• Vital signs, heart rate

  One time at the start of the study visit.

• Vital signs, noninvasive blood pressure

  One time at the start of the study visit.

• Vital signs, oxygen hemoglobin saturation

  One time at the start of the study visit.

• Vital signs, temperature

  One time at the start of the study visit.

Study Arms (1)

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

Drug: Observational

Interventions

Observational DRUG

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.

Adult patients treated with duloxetine for fibromyalgia

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Patients treated at the Pain Management Center (PMC) at the University of Utah who meet inclusion criteria.

You may qualify if:

• Adults 18+
• Meeting diagnostic criteria for Fibromyalgia
• Patients taking Duloxetine 60 mg/day for at least 8 weeks

You may not qualify if:

• 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).

Sponsors & Collaborators

• University of Utah: lead

Study Sites (1)

Pain Management Center and Pain Research Center at the University of Utah

Salt Lake City, Utah, 84132, United States

RECRUITING

Biospecimen

Retention: SAMPLES WITH DNA

10 mL blood sample will be obtained for a plasma duloxetine concentration and genotyping of CYP2D6 and CYP1A2. Blood samples will be obtained four hours after the morning dose with patients being nil per os to minimize the effect of gastric contents on duloxetine bioavailability.

MeSH Terms

Conditions

Fibromyalgia

Interventions

Watchful Waiting

Condition Hierarchy (Ancestors)

Muscular Diseases; Musculoskeletal Diseases; Rheumatic Diseases; Neuromuscular Diseases; Nervous System Diseases

Intervention Hierarchy (Ancestors)

Outcome Assessment, Health Care; Outcome and Process Assessment, Health Care; Quality of Health Care; Health Services Administration

Study Officials

• Jake Steenblick, DNP

  University of Utah

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Jake Steenblick, DNP

CONTACT

801-585-1216; jacob.steenblik@nurs.utah.edu

Natalie R Bennion, MPH

CONTACT

801-585-7697; Natalie.Bennion@utah.edu

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Target Duration: 12 Months
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor (Clinical)

Study Record Dates

• First Submitted: March 4, 2025
• First Posted: March 10, 2025
• Study Start: May 1, 2025
• Primary Completion: May 1, 2026
• Study Completion: May 1, 2026
• Last Updated: August 21, 2025

Record last verified: 2025-07

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)