Testing Doxycycline Hyclate for bacterial sexually transmitted diseases
Official title: Doxycycline Intervention for Bacterial STI ChemoprOphylaxis (DISCO)
A Randomized Trial of Doxycycline Chemoprophylaxis for the Prevention of Sexually Transmitted Infections in Gay, Bisexual and Other Men Who Have Sex With Men (gbMSM)
- 2 groups
- Sites in Calgary, Vancouver and 4 more cities
- Recruiting
Interventions
- Medication
Doxycycline Hyclate
STI PrEP arm: doxycycline capsules 100mg orally daily for 12 months STI PEP arm: doxycycline 200mg orally once within 24-72 hours following each sexual encounter deemed at risk (i.e. condomless anal or oral sex), to a maximum of six pills (i.e. 600 mg total) per week
Canadian Sites (6)
4 of 6 recruiting
- Recruiting
Sheldon Chumir Centre
Calgary, Alberta
- Recruiting
BC Centre for Disease Control
Vancouver, British Columbia
- Recruiting
St. Michael's Hospital
Toronto, Ontario
- Recruiting
McGill University Health Centre
Montreal, Quebec
- Not yet recruiting
St. Joseph's Healthcare Hamilton
Hamilton, Ontario
- Not yet recruiting
The Ottawa Hospital
Ottawa, Ontario
Eligibility Criteria
See who this study is looking for9 criteria
The trial’s own eligibility text, word for word from the registry. Only the trial site can say who takes part.
Inclusion
- +Males, ≥ 18 years of age;
- +Any sexual activity (i.e. oral sex, insertive or receptive anal sex, with or without a condom) with more than one male partner in the preceding 12 months;
- +Intention to remain sexually active with more than one male partner in the next 12 months;
- +At least one prior episode of a previously diagnosed and adequately treated syphilis, gonorrhea or chlamydia infection within 12 months prior to screeningScreeningThe checks done before joining, to see whether a study fits.Read more →.
Exclusion
- −Known allergy to doxycycline or tetracyclines;
- −Existing chronic or intermittent tetracycline or doxycycline use (e.g. for chronic osteomyelitis, acne).
- −Use of medications which could lower doxycycline levels, including barbiturates, phenytoin and carbamazepine.
- −Individuals currently using isotretinoin;
- −Any individual capable of becoming pregnant.
In plain language
Assembled directly from this trial’s registry record. Every sentence traces to a field below — nothing here is generated or interpreted.
What this study is
This study is testing a way to prevent a condition from developing.
This study is not organised into the usual phase numbers — that is common for device, behavioural, and diagnostic research.
From the trial registry
Built from these fields:
- designModule.designInfo.primaryPurpose
- designModule.phases
Who receives what
There are 2 groups in this study.
Groups A and B receive Doxycycline Hyclate.
Registry label: A: STI PrEP arm · B: STI PEP arm
From the trial registry
Built from these fields:
- armsInterventionsModule.armGroups[].label
- armsInterventionsModule.armGroups[].type
- armsInterventionsModule.armGroups[].interventionNames
How the study is run
Which group you would be placed in is decided by chance, like a coin flip — not by you and not by your doctor.
This study is open-labelOpen-labelEveryone knows which treatment is being given — nothing is hidden.Read more →: everyone knows which treatment is being given, including you and the study team.
From the trial registry
Built from these fields:
- designModule.designInfo.allocation
- designModule.designInfo.maskingInfo.masking
Is there a placebo?
This study does not list a placeboPlaceboA dummy treatment with no active medicine, used for comparison.Read more → group.
From the trial registry
Built from these fields:
- armsInterventionsModule.armGroups[].type
- armsInterventionsModule.armGroups[].interventionNames
Who the study is looking for
The study lists a minimum age of 18 years, with no upper limit given.
The study lists male participants only.
The study does not accept healthy volunteersHealthy volunteerSomeone without the condition being studied who takes part anyway.Read more →.
These are the criteria the study lists. Only the trial siteTrial siteA hospital or clinic where a study is actually run.Read more → can decide whether someone can take part.
From the trial registry
Built from these fields:
- eligibilityModule.minimumAge
- eligibilityModule.sex
- eligibilityModule.healthyVolunteers
How big and how long
The study aims to enrol about 560 people.
The study is currently expected to finish around June 2027.
The main measurement is taken over: 60 weeks.
From the trial registry
Built from these fields:
- designModule.enrollmentInfo.count
- statusModule.completionDateStruct.date
- outcomesModule.primaryOutcomes[].timeFrame
What the study measures
Plasma doxycycyline levels to determine efficacy of doxycycline chemoprophylaxis — measured over 60 weeks.
From the trial registry
Built from these fields:
- outcomesModule.primaryOutcomes[].measure
- outcomesModule.primaryOutcomes[].timeFrame
Source: NCT04762134 on ClinicalTrials.gov. The full registry text is further down this page — this summary never replaces it.
Not medical advice. What do these terms mean?
What is being tested — in plain terms
About Doxycycline HyclateDrug
STI PrEP arm: doxycycline capsules 100mg orally daily for 12 months STI PEP arm: doxycycline 200mg orally once within 24-72 hours following each sexual encounter deemed at risk (i.e. condomless anal or oral sex), to a maximum of six pills (i.e. 600 mg total) per week
From the trial registry — its own words, unedited.
What a drug is here: A medicine — a chemical or small-molecule treatment — given as the thing being studied.
Read the full explanation → · in clinical review
Common questions
Answered from this trial’s registry record. Where the record doesn’t say, these answers say so rather than filling the gap.
Am I eligible for this trial?
Only the trial siteTrial siteA hospital or clinic where a study is actually run.Read more → can decide whether someone can take part. Concord cannot make that determination, and neither can any tool that has not examined you.
What the study lists: a minimum age of 18 years.
The full inclusionInclusion criteriaThe things you must have or be for a study to consider you.Read more → and exclusion criteriaExclusion criteriaThe things that would prevent someone from taking part.Read more → are published on this page, exactly as the study team wrote them.
The useful next step is to bring this trial to your doctor. Answering a few questions first gives them something concrete to review.
From the trial registry
- eligibilityModule.minimumAge
- eligibilityModule.eligibilityCriteria
Is there a placebo?
This study does not list a placeboPlaceboA dummy treatment with no active medicine, used for comparison.Read more → group.
From the trial registry
- armsInterventionsModule.armGroups[].type
Would I know which treatment I am getting?
This study is open-labelOpen-labelEveryone knows which treatment is being given — nothing is hidden.Read more →: everyone knows which treatment is being given, including you and the study team.
Which group you would be placed in is decided by chance, like a coin flip — not by you and not by your doctor.
From the trial registry
- designModule.designInfo.maskingInfo.masking
- designModule.designInfo.allocation
Who can join?
The study lists a minimum age of 18 years, with no upper limit given.
It lists male participants only.
It does not accept healthy volunteersHealthy volunteerSomeone without the condition being studied who takes part anyway.Read more →.
Only the trial siteTrial siteA hospital or clinic where a study is actually run.Read more → can confirm whether a particular person can take part.
From the trial registry
- eligibilityModule.minimumAge
- eligibilityModule.sex
- eligibilityModule.healthyVolunteers
How long would this take?
The study's main measurement is taken over: 60 weeks.
The study as a whole is currently expected to finish around 2027-06-30.
How long any one person takes part can differ from the study length. The study team can tell you what the schedule looks like in practice.
From the trial registry
- outcomesModule.primaryOutcomes[].timeFrame
- statusModule.completionDateStruct.date
How many people are taking part?
The study aims to enrol about 560 people.
From the trial registry
- designModule.enrollmentInfo.count
Where is this happening?
This study lists 6 locations, including: Calgary, Alberta, Canada; Vancouver, British Columbia, Canada; Hamilton, Ontario, Canada; Ottawa, Ontario, Canada; Toronto, Ontario, Canada; Montreal, Quebec, Canada.
Sites can open and close during a study, so confirm with the team before travelling.
From the trial registry
- trial_locations
About This Trial
There is a growing epidemic of the bacterial sexually transmitted infections (STIs) syphilis, chlamydia and gonorrhea worldwide; similarly concerning trends have been noted in Canada, where increases of over 160% have been seen in bacterial STIs over the last decade. In Canada, gay, bisexual, and other men who have sex with men (gbMSM) - including those living with HIV - are disproportionately impacted by bacterial STIs5,6These dramatic increases in bacterial STIs, the potential development of serious complications including AMR, and waning effectiveness of the promotion of conventional STI prevention tools (e.g. condoms), signals the need for novel STI prevention strategies and tools to mitigate STI-related complications. A rigorous randomized controlled trial will be conducted to compare STI PrEP vs. STI PEP and definitively assess the efficacy, safety, antimicrobial resistance profiles and costs associated with doxycycline-based STI prevention.
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See if this trial could fit youThis page is for informational purposes only and does not constitute medical advice. Clinical trial eligibility can only be determined by the trial site after proper screening. Trial information is sourced from ClinicalTrials.gov and may not reflect the most current status. Always consult your healthcare provider before making decisions about clinical trial participation.