NCT07226440 · University of California, San Francisco
Examining a Novel Gastrointestinal Intervention to Negate Environmental Toxicants (ENGINE)
(ENGINE)
What this study is about
This randomly assigned, compared against an inactive treatment crossover trial will test the feasibility and acceptability of using colesevelam in male firefighters with high per- and polyfluoroalkyl substances (PFAS) exposure. This trial will also explore whether colesevelam lowers blood PFAS levels and urine environmental toxicant and mold mycotoxin levels.
View original scientific description
This randomized, placebo-controlled crossover trial will test the feasibility and acceptability of using colesevelam in male firefighters with high per- and polyfluoroalkyl substances (PFAS) exposure. This trial will also explore whether colesevelam lowers blood PFAS levels and urine environmental toxicant and mold mycotoxin levels.
Interventions
DRUG
Colesevelam
Colesevelam in 625-mg tablets. Participants will take 3 tablets orally, twice daily (total daily dose 3.75 g) for 12 weeks.
DRUG
Placebo
Matching inert oral tablets designed to mimic colesevelam 625 mg tablets in size, shape, and color, but containing no active pharmaceutical ingredient. Participants will take 3 orally, twice per day for 12 weeks.
Primary outcome measures
Retention
Time frame: Enrollment to Week 27
Proportion completing all study blood draws after consent
Adherence to study drug
Time frame: Enrollment to Week 27
Proportion taking ≥80% of colesevelam doses
Adherence to placebo
Time frame: Enrollment to Week 27
Proportion taking ≥80% of placebo doses
Acceptability
Time frame: Week 27
Proportion endorsing "likely" or "very likely" to refer a co-worker to the study
Likability
Time frame: Week 27
Proportion endorsing "likely" or "very likely" to participate again
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
- Male firefighter, active or retired
- California resident
- Age 18 or older
- English-speaking
- Access to a reliable internet connection
- Willing to attend 3 in-person study visits in the San Francisco Bay Area over about 6.5 months
- Willing to receive weekly text message reminders to complete online surveys
- Willing to complete a mail-based, at-home finger-prick blood test
- Willing to take 3 tablets (each tablet about the size of a multivitamin) orally twice daily for a total of 6 months
- Evaluated by study team to have an elevated risk of PFAS exposure (e.g., duration of firefighting service, prior NASEM-7 result greater than or equal to 10 ng/mL)
Exclusion criteria
- Gastroparesis or other severe gastrointestinal motility disorders
- Bowel obstruction
- History of major gastrointestinal tract surgery
- Dysphagia or difficulty swallowing (due to tablet size)
- History of hypertriglyceridemia (triglycerides exceeding 500 mg/dL)
- History of hypertriglyceridemia-induced pancreatitis
- Type 1 or 2 diabetes
- History of fat-soluble vitamin deficiencies, i.e., vitamins A, D, E, or K
- Phenylketonuria
- History of known bleeding/clotting disorders
- Medications or treatments that may impact the excretion of PFAS, such as activated charcoal, other bile acid sequestrants, chelation therapies, etc.
- Unalterable plans to donate blood or plasma during the study participation period
Where
- San Francisco, California
Related conditions & keywords
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 Apr 24, 2026 · Source of record for eligibility and locations