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Antibiotic

Doxycycline for Syphilis Prevention

Phase 4

Waitlist Available

Led By Troy Grennan, MD

Research Sponsored by British Columbia Centre for Disease Control

Eligibility Criteria Checklist

Specific guidelines that determine who can or cannot participate in a clinical trial

Must have

Males, ≥ 18 years of age at baseline

Self-report condomless anal sex with a man within the last 6 months

Must not have

Use of medications which could lower doxycycline levels, including barbiturates, phenytoin and carbamazepine

Any individual capable of getting pregnant

Timeline

Screening 3 weeks

Treatment Varies

Follow Up at 6 and 12 months

Awards & highlights

All Individual Drugs Already Approved

Approved for 60 Other Conditions

Drug Has Already Been Approved

Pivotal Trial

Summary

This trial is researching an innovative syphilis prevention tool, doxycycline, for gay, bisexual and other men who have sex with men (gbMSM). PrEP and doxycycline are being used to reduce STI rates in HIV-positive gbMSM.

Who is the study for?

The trial is for HIV-positive gay, bisexual, and other men who have sex with men (gbMSM) over 18 years old. Participants must have had condomless anal sex in the past 6 months and a recent syphilis diagnosis. They can't join if they're allergic to doxycycline or tetracyclines, have myasthenia gravis, use isotretinoin or certain other medications.

What is being tested?

This study tests whether taking daily doxycycline can prevent syphilis in high-risk gbMSM compared to a placebo. It builds on previous research suggesting that this antibiotic could be an effective preventive measure against sexually transmitted infections.

What are the potential side effects?

Doxycycline may cause side effects like sun sensitivity leading to severe sunburns, upset stomach, diarrhea, and changes in color of teeth enamel. Allergic reactions are possible but participants with known allergies were excluded.

Eligibility Criteria

Inclusion Criteria

You may be eligible if you check “Yes” for the criteria below

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I am a man and at least 18 years old.

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I have had unprotected anal sex with a man in the past 6 months.

Exclusion Criteria

You may be eligible for the trial if you check “No” for criteria below:

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I am not taking medications like barbiturates, phenytoin, or carbamazepine.

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I am capable of becoming pregnant.

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I am currently taking isotretinoin.

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I have been diagnosed with myasthenia gravis.

Timeline

Screening ~ 3 weeks3 visits

Treatment ~ Varies

Follow Up ~ at 6 and 12 months

Screening ~ 3 weeks

Treatment ~ Varies

Follow Up ~at 6 and 12 months

This trial's timeline: 3 weeks for screening, Varies for treatment, and at 6 and 12 months for reporting.

Treatment Details

Study Objectives

Study objectives can provide a clearer picture of what you can expect from a treatment.

Primary study objectives

Proportion of individuals with adverse event-related study drug discontinuation in each study arm.

To assess the proportion of individuals reporting grade 3 or 4 adverse events in each study arm.

To assess the proportion of individuals with therapeutic doxycycline drug level (defined at ≥ 1000 ng/mL) at each study time point.

+2 more

Secondary study objectives

To assess the changes in sexual risk behaviour will be calculated by comparing risk parameters (i.e. number partners, number of anal sexual encounters that were condomless) from pre-PrEP initiation to the study period.

To assess the incidence of early syphilis infection

To assess the incidence of gonorrhea or chlamydia infection

+1 more

Other study objectives

To assess changes in the bacterial populations found in the rectal microbiome.

Side effects data

From 2022 Phase 4 trial • 449 Patients • NCT04050540

Malaria

100%

80%

60%

40%

20%

Study treatment Arm

Standard of Care Arm

dPEP Intervention Arm

Awards & Highlights

All Individual Drugs Already Approved

Therapies where all constituent drugs have already been approved are likely to have better-understood side effect profiles.

Approved for 60 Other Conditions

This treatment demonstrated efficacy for 60 other conditions.

Drug Has Already Been Approved

The FDA has already approved this drug, and is just seeking more data.

Pivotal Trial

The final step before approval, pivotal trials feature drugs that have already shown basic safety & efficacy.

Trial Design

2Treatment groups

Experimental Treatment

Placebo Group

Group I: Doxycycline armExperimental Treatment1 Intervention

Participants in this intervention group will receive doxycycline 100mg orally daily, which is available as a 100mg capsule. This single daily dose was chosen to maximize adherence, given the common use of once-daily Human Immunodeficiency Virus (HIV) pre-exposure prophylaxis (PrEP), as well as its efficacy as once-daily prophylaxis against malaria and its utility as dosing as infrequent as once weekly for another spirochete infection, leptospirosis.

Group II: Placebo armPlacebo Group1 Intervention

Participants in this control group will receive a placebo capsule identical in appearance, taste, and size to the capsule provided to the intervention group.

Treatment

First Studied

Drug Approval Stage

How many patients have taken this drug

Doxycycline

FDA approved

0 / 6Eligibility criteria met