Chronic PainPhase 2NCT04939623
Novel Use of Probenecid to Alleviate Symptoms of Opioid Withdrawal
A Phase 2 study testing Probenecid in people with Chronic Pain and Drug Dependence of Morphine Type, run by University of Calgary at 1 site in Canada.
Trial summary
The proposed clinical trial will address the problem of opioid withdrawal. Opioids are essential for pain-relief in the short term, but their continued use is associated with a host of adverse effects. Read more about this study
- Who is it for?
- Ages 18 to 80 years
- Conditions the study is for
- Chronic Pain, Drug Dependence of Morphine Type, Symptom, Withdrawal
- What is being tested?
- Probenecid
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 40 participants
- Where
- 1 siteCanada
- Study dates
- 31 Oct 2023to 31 Dec 2026
- Phase
- Phase 2
- 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 to 80 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Adults with chronic pain. Age greater than or equal to 18 years on the day of enrolment.
- Subjects are currently taking a daily opioid pain medication and planning to taper the dose.
- Participants complete at least one voluntary opioid dose reduction in the twelve-week study period.
- Glomerular filtration rate (GFR) > 50 mL/min
- Capable of providing informed consent
Who cannot join
- Allergy to probenecid or related drugs
- History of uric acid renal calculi, if known to be urate calculi. If unknown type, then any history of renal calculi.
- Known G6PD deficiency
- Active gout in any joint
- Current use of drugs whose exposure may be prolonged, or risk of toxicity increased when used in combination with probenecid:
- Penicillins, specifically ampicillin, penicillin G sodium, and piperacillin
Show all 20Show fewer
- Carbapenems, specifically doripenem and meropenem
- Lorazepam, midazolam, nitrazepam
- Ketorolac
- Oseltamivir
- Methotrexate
- Mycophenolate
- Current use of drugs which may mask symptoms of withdrawal:
- Clonidine, lofexidine, tizanidine
- Current use of drugs which may diminish the effect of probenecid:
- High dose salicylates including greater than 325 mg PO daily of acetylsalicylic acid (ASA)
- Pregnancy or breastfeeding
- Any major comorbid medical condition which might impair follow-up or result in a safety risk to the participant
- Participation in another clinical trial investigating a drug, medical device, or a medical procedure during the 30 days prior to enrolment.
- -
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Lori Montgomery contact
Canada1 site, 1 recruiting
- Recruiting
Richmond Road Diagnostic and Treatment Centre
Calgary, Alberta, T2T 5C7
Tammy Eberle, 403-943-9900, tammy.eberle@ahs.ca
Lori Montgomery, 403-943-9900, lori.montgomery@ahs.ca
About this study
Official title: Novel Use of Probenecid to Alleviate Symptoms of Opioid Withdrawal in People With Chronic Pain Undergoing Voluntary Opioid Tapering: a Pilot Study
The proposed clinical trial will address the problem of opioid withdrawal. Opioids are essential for pain-relief in the short term, but their continued use is associated with a host of adverse effects. People living with chronic pain who were initiated on opioid therapy now find themselves with a major life-changing problem - dependence on opioid medications. Opioid withdrawal symptoms are a key barrier to decreasing or stopping their opioid medication. Currently, there are few medications that ameliorate the symptoms of opioid withdrawal. This problem is a major part of the opioid crisis in Canada, and impacts people across all demographics and socioeconomic status. A misconception is that only individuals with opioid use disorder are susceptible to opioid withdrawal; on the contrary, appropriate use of prescription opioids to manage pain can lead to significant symptoms of opioid withdrawal when it is reduced or stopped. Patients in Alberta who are at risk for opioid withdrawal, either from prescribed use or misuse will be primarily impacted by this trial.
The investigators have recently explored the underlying causes of opioid withdrawal and identified an important target in the spinal cord that is responsible for producing withdrawal symptoms in rats and mice. The target, a protein called pannexin-1 (Panx1), is located throughout the body, specifically in the brain and spinal cord. Using sophisticated biochemical, genetic, and pharmacological techniques, the investigators demonstrated how Panx1 on immune cells is implicated in the production of opioid withdrawal symptoms after cessation of fentanyl and morphine in opioid dependent rodents. The investigators then attenuated these symptoms of withdrawal using probenecid, a drug which inherently blocks Panx1 activity. Because probenecid is a safe and clinically available drug, the findings could be immediately translated into clinical therapy to support people who are struggling with the symptoms of opioid withdrawal and provide clinicians with a safe and effective option for caring for this population.
Read the detailed description
The proposed clinical trial will address the problem of opioid withdrawal. Opioids are essential for pain-relief in the short term, but their continued use is associated with a host of adverse effects. People living with chronic pain who were initiated on opioid therapy now find themselves with a major life-changing problem - dependence on opioid medications. Opioid withdrawal symptoms are a key barrier to decreasing or stopping their opioid medication. Currently, there are few medications that ameliorate the symptoms of opioid withdrawal. This problem is a major part of the opioid crisis in Canada, and impacts people across all demographics and socioeconomic status. A misconception is that only individuals with opioid use disorder are susceptible to opioid withdrawal; on the contrary, appropriate use of prescription opioids to manage pain can lead to significant symptoms of opioid withdrawal when it is reduced or stopped. Patients in Alberta who are at risk for opioid withdrawal, either from prescribed use or misuse will be primarily impacted by this trial.
Our team has recently explored the underlying causes of opioid withdrawal and identified an important target in the spinal cord that is responsible for producing withdrawal symptoms in rats and mice. The target, a protein called pannexin-1 (Panx1), is located throughout the body, specifically in the brain and spinal cord. Using sophisticated biochemical, genetic, and pharmacological techniques, the investigators demonstrated how Panx1 on immune cells is implicated in the production of opioid withdrawal symptoms after cessation of fentanyl and morphine in opioid dependent rodents. The investigators then attenuated these symptoms of withdrawal using probenecid, a drug which inherently blocks Panx1 activity. Because probenecid is a safe and clinically available drug, the findings could be immediately translated into clinical therapy to support people who are struggling with the symptoms of opioid withdrawal and provide clinicians with a safe and effective option for caring for this population.
Probenecid was initially developed in the early 1950s as a tool to enhance the activity of penicillin and allow for outpatient treatment of various infections. It increases plasma levels and the half-life of weak organic acids (penicillins, cephalosporins, or other beta-lactam antibiotics) by competitively inhibiting their renal tubular secretion. As a result, it became widely used in combination with beta-lactam antibacterial agents. It is still occasionally used today in combination with cefazolin for the treatment of skin and soft tissue infections, and in combination with cefoxitin or doxycycline as an option for outpatient treatment of pelvic inflammatory disease.
Probenacid also competitively inhibits active reabsorption of uric acid at the level of the proximal convoluted tubule promoting excretion of uric acid, thereby reducing serum urate concentrations.
Probenecid is also used in combination with cidofovir for the prevention of cidofovir-related nephrotoxicity when used to treat cytomegalovirus retinitis in patients with HIV. More recently, the effects of probenecid on serotonin levels and TRPV2 channels has led to speculation about its utility in depression, Parkinson's Disease, and congestive heart failure.
The drug is no longer commercially available in Canada but is commercially available as 500 mg tablets in the United States which can be acquired through Health Canada's Special Access Program. Probenecid can, however, be prepared in Canada by compounding pharmacies.
The study is a single centre, randomized, double blind, placebo-controlled, 12-week clinical trial meant to study probenecid use among adult participants living with chronic non-cancer pain using opioid drug therapy on a daily basis and planning to voluntarily reduce their dose.
- Being tested
- Probenecid
- Medical subject headings
- Chronic Pain, Substance Withdrawal Syndrome
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
ProbenecidDrug
Also called 4-(Dipropylsulfamoyl)benzoic acid, Benemid, Probalan
The Investigators aim to recruit 40 participants who will be followed for 12 weeks in duration. Participants will be randomized in a 2:2:1 ratio to one of probenecid 500 mg, 1000 mg, or placebo PO BID for 12 weeks. Justification for use of a non-active placebo comparator includes the fact that this trial is meant to identify tolerability and safety of probenecid in a population of patients living with chronic pain, this will be best measured by comparing to a non-active placebo.
| Study group | Role | What they receive |
|---|---|---|
| Probenecid 500 mg PO BID | Active comparator | Probenecid 500 mg X 1 PO BID and Placebo X 1 PO BID Receives: Drug: Probenecid |
| Probenecid 1000 mg PO BID | Active comparator | Probenecid 500mg X 2 PO BID Receives: Drug: Probenecid |
| Placebo PO BID | Placebo comparator | Placebo X 2 PO BID Receives: Drug: Probenecid |
What is being measured
The primary outcome is the main question the study is designed to answer.
To evaluate tolerability of oral probenecid in patients undergoing voluntary opioid tapering
Tolerability will be assessed through use of the "SAFTEE-SI questionnaire recorded as a percentage for each of the three group assignments and again in two groups titled "probenecid" and "placebo".
Statistical comparisons will be made between groups with regard to the percentage of participants experiencing any given adverse event. (example: rash occurred at a rate of 0% with placebo, 2% with probenecid 500 mg, and 4% with probenecid 1000 mg). Comparisons will also be made between the "probenecid group" and "placebo group" (Example: Blurred vision occurred at a rate of 2% with placebo compared to 4% with probenecid)
Measured: 12 weeks
To evaluate acceptability of oral probenecid in patients undergoing voluntary opioid tapering
Acceptability will be measured by assessing the Percent of patients achieving 80% compliance in each group as measured by returned supply in medication vials.
Measured: 12 weeks
To evaluate safety of oral probenecid in patients undergoing voluntary
Safety will be assessed by the clinical research team who have diagnosed the adverse events which will be recorded as a percentage for each of the three group assignments and again in two groups titled "probenecid" and "placebo".
Statistical comparisons will be made between groups with regard to the percentage of participants experiencing any given adverse event. (example: rash occurred at a rate of 0% with placebo, 2% with probenecid 500 mg, and 4% with probenecid 1000 mg). Comparisons will also be made between the "probenecid group" and "placebo group" (Example: Blurred vision occurred at a rate of 2% with placebo compared to 4% with probenecid)
Measured: 12 weeks
Secondary outcomes (2)
To evaluate the feasibility of treatment with probenecid in a patient-directed opioid tapering protocol, in the setting of an interdisciplinary pain clinic
To evaluate the feasibility of treatment with probenecid in a patient-directed opioid tapering protocol, in the setting of an interdisciplinary pain clinic. The sample size of enrolling 40 subjects over a 3 year period will be be used to evaluate the feasibility of a larger study using a similar protocol.
Measured: 3 years
To evaluate whether Panx1 gene variants correlate with opioid withdrawal severity and response to probenecid by collecting salivary samples and performing DNA extraction in a small cohort.
A summary of association analyses between subjects DNA samples will be evaluated to determine PANX1 genetic variants and then analyzed for corellation with the study endpoints (e.g. adverse events, opioid withdrawal) and then be reported by treatment group.
Measured: 3 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted25 Jun 2021
- Study start31 Oct 2023
- Primary completion31 Dec 2026 (estimated)
- Study completion31 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (4)Papers the sponsor has linked to this study.
- Other trials for Chronic PainStudies of the same condition, open and under way.
- More trials run by University of CalgaryThe 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
- Interventional
- Phase
- Phase 2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- 40 participants will be randomized in a 2:2:1 ratio to one of: 1. Probenecid 500 mg PO BID (16 participants) 2. Probenecid 1000 mg PO BID (16 participants) 3. Placebo PO BID (8 participants)
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 40 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Calgary
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Lori Montgomery, MD, Principal investigator, University of Calgary
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04939623
- Sponsor's protocol ID
- Probenacid 1.0
- Status last verified
- Dec 2025
- First submitted
- 11 Sep 2020
- Last updated
- 1 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
1 Beyer, R. H., Wiebelhaus, V. D., Russe, H. F., Peck, H. M., & McKinney, S. E. (1950). Benemid: An anticatabolite; its phar- macological properties. Federation Proceedings, 9, 258.
Probenecid CPhA Monograph. RxTx. Date of Revision: November 2017. Accessed online at https://www.e-therapeutics.ca on February 21, 2018.
Robbins N, Koch SE, Tranter M, Rubinstein J. The history and future of probenecid. Cardiovasc Toxicol. 2012 Mar;12(1):1-9. doi: 10.1007/s12012-011-9145-8.
PubMed 21938493Benuryl Tablets, Probenecid Tablets. Prescribing Information. Montreal, Quebec. Valeant Canada LP. Date of Revision: September 1, 2004.
Study at a glance
From the registry record, last updated by the sponsor on 1 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Novel Use of Probenecid to Alleviate Symptoms of Opioid Withdrawal in People With Chronic Pain Undergoing Voluntary Opioid Tapering: a Pilot Study
- ClinicalTrials.gov ID
- NCT04939623
- Acronym / sponsor ID
- Probenacid 1.0
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 40 participants (estimated)
- Lead sponsor
- University of CalgaryUniversity, hospital or other
- Study start
- 31 Oct 2023 (actual)
- Primary completion
- 31 Dec 2026 (estimated)
- Study completion
- 31 Dec 2026 (estimated)
- First posted
- 25 Jun 2021 (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.
The proposed clinical trial will address the problem of opioid withdrawal. Opioids are essential for pain-relief in the short term, but their continued use is associated with a host of adverse effects. People living with chronic pain who were initiated on opioid therapy now find themselves with a major life-changing problem - dependence on opioid medications. Opioid withdrawal symptoms are a key barrier to decreasing or stopping their opioid medication. Currently, there are few medications that ameliorate the symptoms of opioid withdrawal. This problem is a major part of the opioid crisis in Canada, and impacts people across all demographics and socioeconomic status. A misconception is that only individuals with opioid use disorder are susceptible to opioid withdrawal; on the contrary, appropriate use of prescription opioids to manage pain can lead to significant symptoms of opioid withdrawal when it is reduced or stopped. Patients in Alberta who are at risk for opioid withdrawal, either from prescribed use or misuse will be primarily impacted by this trial.
The investigators have recently explored the underlying causes of opioid withdrawal and identified an important target in the spinal cord that is responsible for producing withdrawal symptoms in rats and mice. The target, a protein called pannexin-1 (Panx1), is located throughout the body, specifically in the brain and spinal cord. Using sophisticated biochemical, genetic, and pharmacological techniques, the investigators demonstrated how Panx1 on immune cells is implicated in the production of opioid withdrawal symptoms after cessation of fentanyl and morphine in opioid dependent rodents. The investigators then attenuated these symptoms of withdrawal using probenecid, a drug which inherently blocks Panx1 activity. Because probenecid is a safe and clinically available drug, the findings could be immediately translated into clinical therapy to support people who are struggling with the symptoms of opioid withdrawal and provide clinicians with a safe and effective option for caring for this population.
Detailed description
The proposed clinical trial will address the problem of opioid withdrawal. Opioids are essential for pain-relief in the short term, but their continued use is associated with a host of adverse effects. People living with chronic pain who were initiated on opioid therapy now find themselves with a major life-changing problem - dependence on opioid medications. Opioid withdrawal symptoms are a key barrier to decreasing or stopping their opioid medication. Currently, there are few medications that ameliorate the symptoms of opioid withdrawal. This problem is a major part of the opioid crisis in Canada, and impacts people across all demographics and socioeconomic status. A misconception is that only individuals with opioid use disorder are susceptible to opioid withdrawal; on the contrary, appropriate use of prescription opioids to manage pain can lead to significant symptoms of opioid withdrawal when it is reduced or stopped. Patients in Alberta who are at risk for opioid withdrawal, either from prescribed use or misuse will be primarily impacted by this trial.
Our team has recently explored the underlying causes of opioid withdrawal and identified an important target in the spinal cord that is responsible for producing withdrawal symptoms in rats and mice. The target, a protein called pannexin-1 (Panx1), is located throughout the body, specifically in the brain and spinal cord. Using sophisticated biochemical, genetic, and pharmacological techniques, the investigators demonstrated how Panx1 on immune cells is implicated in the production of opioid withdrawal symptoms after cessation of fentanyl and morphine in opioid dependent rodents. The investigators then attenuated these symptoms of withdrawal using probenecid, a drug which inherently blocks Panx1 activity. Because probenecid is a safe and clinically available drug, the findings could be immediately translated into clinical therapy to support people who are struggling with the symptoms of opioid withdrawal and provide clinicians with a safe and effective option for caring for this population.
Probenecid was initially developed in the early 1950s as a tool to enhance the activity of penicillin and allow for outpatient treatment of various infections. It increases plasma levels and the half-life of weak organic acids (penicillins, cephalosporins, or other beta-lactam antibiotics) by competitively inhibiting their renal tubular secretion. As a result, it became widely used in combination with beta-lactam antibacterial agents. It is still occasionally used today in combination with cefazolin for the treatment of skin and soft tissue infections, and in combination with cefoxitin or doxycycline as an option for outpatient treatment of pelvic inflammatory disease.
Probenacid also competitively inhibits active reabsorption of uric acid at the level of the proximal convoluted tubule promoting excretion of uric acid, thereby reducing serum urate concentrations.
Probenecid is also used in combination with cidofovir for the prevention of cidofovir-related nephrotoxicity when used to treat cytomegalovirus retinitis in patients with HIV. More recently, the effects of probenecid on serotonin levels and TRPV2 channels has led to speculation about its utility in depression, Parkinson's Disease, and congestive heart failure.
The drug is no longer commercially available in Canada but is commercially available as 500 mg tablets in the United States which can be acquired through Health Canada's Special Access Program. Probenecid can, however, be prepared in Canada by compounding pharmacies.
The study is a single centre, randomized, double blind, placebo-controlled, 12-week clinical trial meant to study probenecid use among adult participants living with chronic non-cancer pain using opioid drug therapy on a daily basis and planning to voluntarily reduce their dose.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 3
- Model description
- 40 participants will be randomized in a 2:2:1 ratio to one of: 1. Probenecid 500 mg PO BID (16 participants) 2. Probenecid 1000 mg PO BID (16 participants) 3. Placebo PO BID (8 participants)
| Arm | Type | Receives |
|---|---|---|
| Probenecid 500 mg PO BID | Active comparator | Drug: ProbenecidProbenecid 500 mg X 1 PO BID and Placebo X 1 PO BID |
| Probenecid 1000 mg PO BID | Active comparator | Drug: ProbenecidProbenecid 500mg X 2 PO BID |
| Placebo PO BID | Placebo comparator | Drug: ProbenecidPlacebo X 2 PO BID |
Who may qualify
- Ages
- 18 to 80 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Adults with chronic pain. Age greater than or equal to 18 years on the day of enrolment.
- Subjects are currently taking a daily opioid pain medication and planning to taper the dose.
- Participants complete at least one voluntary opioid dose reduction in the twelve-week study period.
- Glomerular filtration rate (GFR) > 50 mL/min
- Capable of providing informed consent
Key exclusion criteria (20 listed)
- Allergy to probenecid or related drugs
- History of uric acid renal calculi, if known to be urate calculi. If unknown type, then any history of renal calculi.
- Known G6PD deficiency
- Active gout in any joint
- Current use of drugs whose exposure may be prolonged, or risk of toxicity increased when used in combination with probenecid:
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 |
|---|---|---|
| ProbenecidAlso: 4-(Dipropylsulfamoyl)benzoic acid, Benemid, ProbalanThe Investigators aim to recruit 40 participants who will be followed for 12 weeks in duration. Participants will be randomized in a 2:2:1 ratio to one of probenecid 500 mg, 1000 mg, or placebo PO BID for 12 weeks. Justification for use of a non-active placebo comparator includes the fact that this trial is meant to identify tolerability and safety of probenecid in a population of patients living with chronic pain, this will be best measured by comparing to a non-active placebo. | Drug | Placebo PO BID, Probenecid 1000 mg PO BID, Probenecid 500 mg PO BID |
Primary outcome
To evaluate tolerability of oral probenecid in patients undergoing voluntary opioid tapering
Time frame: 12 weeks
Tolerability will be assessed through use of the "SAFTEE-SI questionnaire recorded as a percentage for each of the three group assignments and again in two groups titled "probenecid" and "placebo". Statistical comparisons will be made between groups with regard to the percentage of participants experiencing any given adverse event. (example: rash occurred at a rate of 0% with placebo, 2% with probenecid 500 mg, and 4% with probenecid 1000 mg). Comparisons will also be made between the "probenecid group" and "placebo group" (Example: Blurred vision occurred at a rate of 2% with placebo compared to 4% with probenecid)
To evaluate acceptability of oral probenecid in patients undergoing voluntary opioid tapering
Time frame: 12 weeks
Acceptability will be measured by assessing the Percent of patients achieving 80% compliance in each group as measured by returned supply in medication vials.
To evaluate safety of oral probenecid in patients undergoing voluntary
Time frame: 12 weeks
Safety will be assessed by the clinical research team who have diagnosed the adverse events which will be recorded as a percentage for each of the three group assignments and again in two groups titled "probenecid" and "placebo". Statistical comparisons will be made between groups with regard to the percentage of participants experiencing any given adverse event. (example: rash occurred at a rate of 0% with placebo, 2% with probenecid 500 mg, and 4% with probenecid 1000 mg). Comparisons will also be made between the "probenecid group" and "placebo group" (Example: Blurred vision occurred at a rate of 2% with placebo compared to 4% with probenecid)
2 secondary outcomes
To evaluate the feasibility of treatment with probenecid in a patient-directed opioid tapering protocol, in the setting of an interdisciplinary pain clinic
Time frame: 3 years
To evaluate whether Panx1 gene variants correlate with opioid withdrawal severity and response to probenecid by collecting salivary samples and performing DNA extraction in a small cohort.
Time frame: 3 years
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 1 May 2026.
- Background1 Beyer, R. H., Wiebelhaus, V. D., Russe, H. F., Peck, H. M., & McKinney, S. E. (1950). Benemid: An anticatabolite; its phar- macological properties. Federation Proceedings, 9, 258.
- BackgroundProbenecid CPhA Monograph. RxTx. Date of Revision: November 2017. Accessed online at https://www.e-therapeutics.ca on February 21, 2018.
- Background: PubMed 21938493Robbins N, Koch SE, Tranter M, Rubinstein J. The history and future of probenecid. Cardiovasc Toxicol. 2012 Mar;12(1):1-9. doi: 10.1007/s12012-011-9145-8.
- BackgroundBenuryl Tablets, Probenecid Tablets. Prescribing Information. Montreal, Quebec. Valeant Canada LP. Date of Revision: September 1, 2004.
- 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.
Lori Montgomery contact
Lori Montgomery, MD principal investigator
University of Calgary
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing Probenecid in people with Chronic Pain and Drug Dependence of Morphine Type, run by University of Calgary at 1 site in Canada.
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 5 inclusion and 20 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 1 May 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 Canada. 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. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
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 Tammy Eberle (1-403-943-9900, tammy.eberle@primarycarealberta.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
To evaluate tolerability of oral probenecid in patients undergoing voluntary opioid tapering (time frame: 12 weeks). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT04939623, which also lists 4 linked publications.
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 1 May 2026.