Doxycycline for Chlamydia

Recruiting at 12 trial locations

Overseen By Julia C. Dombrowski

Age: Any Age

Sex: Any

Trial Phase: Phase 4

Sponsor: National Institute of Allergy and Infectious Diseases (NIAID)

Must not be taking: Antibiotics, Retinoids, Barbiturates, others

Disqualifiers: Pelvic pain, Pregnancy, Allergy, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Prior Safety Data This treatment has passed at least one previous human trial

Approved in 5 Jurisdictions This treatment is already approved in other countries

Compensation: Varies

Number of Visits: 2

Duration: 7 days

664 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial tests two different doxycycline regimens for treating chlamydia infections. The researchers aim to determine if a 3-day course is as effective as a 7-day course. Both men with rectal chlamydia and women with urogenital chlamydia are eligible to join. Participants must have a confirmed chlamydia infection and be willing to follow study procedures, including completing the medication regimen and avoiding certain activities during the trial. As a Phase 4 trial, this research seeks to understand how the already FDA-approved and effective treatment can benefit more patients.

Will I have to stop taking my current medications?

The trial does not specify if you must stop taking your current medications, but you cannot use certain antibiotics or medications that interfere with doxycycline during the study. If you are on any of these, you may need to stop them before joining the trial.

What is the safety track record for doxycycline?

A previous study found doxycycline very effective in treating chlamydia infections. For rectal chlamydia, the treatment cured the infection in every participant. This means everyone in the study eliminated the infection with doxycycline.

Regarding safety, research has shown that doxycycline is generally well-tolerated, with most people experiencing no serious side effects. Since the FDA has already approved doxycycline for treating chlamydia, its safety has been thoroughly studied. Common side effects might include mild stomach upset or sensitivity to sunlight, but these are usually not severe.

Overall, doxycycline has a strong history of being both safe and effective for treating chlamydia. ^{1 2 3 4 5}

Why are researchers enthusiastic about this study treatment?

Unlike the standard of care for Chlamydia, which usually involves a week-long course of antibiotics like doxycycline or azithromycin, this treatment explores a shorter regimen of doxycycline. Researchers are excited because it involves taking doxycycline for just three days, followed by four days of placebo, potentially making it easier for patients to complete their treatment. If effective, this could lead to improved patient adherence and outcomes, as fewer days of medication can be more convenient and reduce the likelihood of missed doses.

What is the effectiveness track record for doxycycline in treating chlamydia?

Studies have shown that doxycycline effectively treats both urogenital and rectal chlamydia infections. For urogenital chlamydia, doxycycline typically cures 95% to 100% of cases. In rectal chlamydia, one study found that doxycycline achieved a 100% cure rate. Another study demonstrated that doxycycline outperforms azithromycin for rectal infections, with success rates of 99% compared to 83% for azithromycin. In this trial, participants will receive doxycycline in different treatment arms to further evaluate its effectiveness. Doxycycline's proven success makes it a reliable choice for treating chlamydia. ^{1 6 7 8 9}

Who Is on the Research Team?

Christine Khosropour, PhD, MPH

Principal Investigator

University of Washington

Julia Dombrowski, MD, MPH

Principal Investigator

University of Washington

Are You a Good Fit for This Trial?

This trial is for individuals aged 16 or older with untreated chlamydia, willing to take a week-long drug regimen and abstain from unprotected sex during the study. Pregnant or breastfeeding individuals, those on certain medications, planning pregnancy, moving away soon, or with severe allergies to tetracyclines are excluded.

Inclusion Criteria

Willing and able to understand and provide written informed consent before initiation of any study procedures

Willing to complete a 7-day study drug regimen

Willing and able to adhere to planned study procedures for all study visits

Exclusion Criteria

Known moderate to severe allergy to tetracyclines, excluding tetracycline-induced photosensitivity

I plan to take antibiotics that work against chlamydia during the study.

Pregnant or lactating, or plan to become pregnant within the study period

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants are randomized to receive either a 3-day or 7-day regimen of doxycycline

7 days

1 visit (in-person) for randomization

Follow-up

Participants are monitored for microbiologic cure and safety, with a re-test for chlamydia at Day 29

4 weeks

1 visit (in-person) at Day 29

What Are the Treatments Tested in This Trial?

Interventions

• Doxycycline

Trial Overview

The study compares two doxycycline treatment regimens for chlamydia: one group takes it for 3 days followed by a placebo for 4 days; the other takes it for a full week. Participants are randomly assigned to these groups and re-tested after four weeks using NAAT.

How Is the Trial Designed?

Group I: Arm 3 Experimental Treatment 2 Interventions

100 mg of doxycycline orally administered twice daily for 3 and 4 days of placebo days to assigned men participants \>/= 16 years old with confirmed rectal Chlamydia trachomatis (CT). N=166.

Group II: Arm 1 Experimental Treatment 2 Interventions

100 mg of doxycycline orally administered twice daily for 3 days and 4 days of placebo to assigned women participants \>/= 16 years old with confirmed urogenital Chlamydia trachomatis (CT). N=166.

Group III: Arm 2 Active Control 1 Intervention

100 mg of doxycycline orally administered twice daily for 7 days to assigned women participants \>/= 16 years old with confirmed urogenital Chlamydia trachomatis (CT). N=166.

Group IV: Arm 4 Active Control 1 Intervention

100 mg of doxycycline orally administered twice daily for 7 days to assigned men participants \>/= 16 years old with confirmed rectal Chlamydia trachomatis (CT). N=166.

Doxycycline is already approved in United States, European Union, Canada, Japan for the following indications:

Approved in United States as Doxycycline for:

• Acne
• Bacterial infections
• Chlamydia
• Gonorrhea
• Lyme disease
• Malaria
• Pneumonia
• Rosacea
• Urinary tract infections

Approved in European Union as Doxycycline for:

• Acne
• Bacterial infections
• Chlamydia
• Gonorrhea
• Lyme disease
• Malaria
• Pneumonia
• Rosacea
• Urinary tract infections

Approved in Canada as Doxycycline for:

• Acne
• Bacterial infections
• Chlamydia
• Gonorrhea
• Lyme disease
• Malaria
• Pneumonia
• Rosacea
• Urinary tract infections

Approved in Japan as Doxycycline for:

• Acne
• Bacterial infections
• Chlamydia
• Gonorrhea
• Lyme disease
• Malaria
• Pneumonia
• Rosacea
• Urinary tract infections

Who Is Running the Clinical Trial?

National Institute of Allergy and Infectious Diseases (NIAID)

Lead Sponsor

Trials

3,361

Recruited

5,516,000+

Emory University

Lead Sponsor

Trials

1,735

Recruited

2,605,000+

Infectious Diseases Clinical Research Consortium

Collaborator

Trials

1

Recruited

660+

Published Research Related to This Trial

In a study involving 111 healthy volunteers, enteric-coated doxycycline hyclate pellets in capsules were found to cause significantly fewer gastrointestinal adverse reactions compared to doxycycline monohydrate tablets, with only 43% of participants reporting side effects versus 66% for monohydrate.

The new formulation demonstrated improved tolerability, particularly reducing incidents of abdominal pain, nausea, and vomiting, making it a safer option for patients requiring doxycycline therapy.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Enteric Coating Reduces Upper Gastrointestinal Adverse Reactions to Doxycycline. Järvinen, A., Nykänen, S., Paasiniemi, L., et al.[2018]

Doxycycline (200 mg/day for 2 weeks) effectively eradicated Chlamydia trachomatis in 89% of patients by the 3rd day and maintained a 100% eradication rate by the 14th day, demonstrating its efficacy in treating nongonococcal urethritis.

The treatment was well-tolerated with no reported side effects, and a significant reduction in symptoms was observed, with 83% of patients symptom-free by the 7th day and 100% by the 14th day.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[Clinical studies on doxycycline in the treatment of nongonococcal urethritis by Chlamydia trachomatis]. Ito, Y., Katoh, N., Takeda, A., et al.[2020]

A systematic evaluation of Chlamydia trachomatis serovars D through K showed that all tested serovars have similar susceptibility to various antibiotics, including levofloxacin, erythromycin, doxycycline, clarithromycin, and azithromycin.

This study confirms previous findings that C. trachomatis exhibits homogeneous susceptibility patterns to these antimicrobial agents, suggesting consistent treatment options across different serovars.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

In vitro activities of several antimicrobial agents against recently isolated and genotyped Chlamydia trachomatis urogenital serovars D through K. Donati, M., Di Francesco, A., D'Antuono, A., et al.[2021]

In a study involving 30 calves with respiratory Chlamydia psittaci infection, the combination therapy of doxycycline and rifampicin did not show a significant advantage over doxycycline alone in terms of disease severity or resolution time.

All treatment groups, including untreated controls, ultimately cleared the infection within 2 weeks, indicating that while doxycycline is the standard treatment, the addition of rifampicin did not enhance efficacy in this model.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Evaluation of antimicrobial treatment in a bovine model of acute Chlamydia psittaci infection: tetracycline versus tetracycline plus rifampicin. Prohl, A., Lohr, M., Ostermann, C., et al.[2015]

In a study of 211 patients, roxithromycin showed a high bacteriological eradication rate of 92.7% for chlamydial infections, comparable to doxycycline's 100%, indicating its effectiveness as a treatment option.

Roxithromycin was associated with fewer drug-related side effects (19%) compared to doxycycline (35%), suggesting it may be a better-tolerated alternative for patients.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Roxithromycin compared to doxycycline in the treatment of genital chlamydial infection and non-specific urethritis. Lidbrink, P., Bygdeman, S., Emtestam, L., et al.[2017]

In a study of 367 patients with Chlamydia trachomatis infections, both doxycycline (100 mg) and spiramycin (1 g) were found to be highly effective, with cure rates of 100% for doxycycline and 98% for spiramycin, indicating that both treatments are viable options.

Spiramycin was associated with a higher incidence of dysethesias in female patients, although these side effects resolved after treatment, suggesting that while effective, further research is needed to explore its safety profile, especially in shorter treatment durations and during pregnancy.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Comparison of spiramycin and doxycycline for treatment of Chlamydia trachomatis genital infections. Dylewski, J., Clecner, B., Dubois, J., et al.[2021]

Doxycycline (Doxy-PEP) has been shown to effectively prevent bacterial sexually transmissible infections (STIs) like chlamydia, gonorrhoea, and syphilis in men who have sex with men with a history of multiple STIs.

Concerns remain regarding potential adverse effects of Doxy-PEP, including the risk of developing antimicrobial resistance and disrupting the microbiome, which clinicians need to discuss with patients considering this preventive treatment.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Interim position statement on doxycycline post-exposure prophylaxis (Doxy-PEP) for the prevention of bacterial sexually transmissible infections in Australia and Aotearoa New Zealand - the Australasian Society for HIV, Viral Hepatitis and Sexual Health Medicine (ASHM). Cornelisse, VJ., Ong, JJ., Ryder, N., et al.[2023]

Doxycycline (DOXY) was found to be clinically effective in treating chlamydial infections in 14 patients, with excellent efficacy observed in 12 evaluable patients after a treatment duration of 4 to 19 days.

No side effects related to doxycycline were reported, indicating a favorable safety profile for this antibiotic in the treatment of Chlamydia trachomatis infections.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[A clinical evaluation of doxycycline in the treatment of genitourinary infections caused by Chlamydia trachomatis]. Sumii, T., Ohnishi, Y., Mita, N., et al.[2016]

In a study of 25 men with non-specific urethritis/adnexitis treated with 200 mg of doxycycline daily for 10 days, 67% of patients were cured and 25% showed improvement, indicating the efficacy of doxycycline in treating chronic infections.

Doxycycline achieved microbiological cure rates of 100% for chlamydial infections, 67% for mycoplasma, 80% for anaerobes, and 57% for aerobes, demonstrating its effectiveness against a range of pathogens, although one patient experienced side effects leading to treatment discontinuation.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[Doxycycline in the treatment of non-specific urethritis and/or prostatitis]. Hofstetter, A., Friesen, A.[2013]

In a study testing 14 strains of Chlamydia psittaci from turkeys, doxycycline showed a minimum inhibitory concentration (MIC) ranging from 0.05 to 0.2 microg/ml, indicating it is effective against these strains.

Enrofloxacin also demonstrated effectiveness with an MIC of 0.25 microg/ml, and importantly, no acquired resistance to either antibiotic was detected, suggesting they remain reliable treatment options.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

In vitro activities of doxycycline and enrofloxacin against European Chlamydia psittaci strains from turkeys. Butaye, P., Ducatelle, R., De Backer, P., et al.[2022]

In a study of 80 heterosexual men with chlamydial urethritis, both pivampicillin and doxycycline were found to be effective treatments, with doxycycline showing slightly better outcomes in terms of clinical failures and persistent infection rates.

Specifically, 12.5% of patients treated with pivampicillin experienced treatment failure compared to 5.1% for doxycycline, although the differences were not statistically significant, indicating that both medications are viable options for treatment.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Pivampicillin versus doxycycline in the treatment of chlamydial urethritis in men. Lassus, AB., Virrankoski, T., Reitamo, SJ., et al.[2013]

Citations

1.

pmc.ncbi.nlm.nih.gov

pmc.ncbi.nlm.nih.gov/articles/PMC6853690/

Treatment Effectiveness of Azithromycin and Doxycycline ...

Azithromycin was found substantially less effective than doxycycline for rectal chlamydia (83% vs 99%) in a meta-analysis of observational studies [12].

2.

nejm.org

nejm.org/doi/full/10.1056/NEJMoa2031631

Azithromycin or Doxycycline for Asymptomatic Rectal ...

A 7-day course of doxycycline was superior to single-dose azithromycin in the treatment of rectal chlamydia infection among men who have sex with men.

3.

cdc.gov

cdc.gov/std/treatment-guidelines/chlamydia.htm

Chlamydial Infections - STI Treatment Guidelines

A randomized trial for the treatment of rectal chlamydia infection among MSM reported microbiologic cure was 100% with doxycycline and 74% with ...

4.

pmc.ncbi.nlm.nih.gov

pmc.ncbi.nlm.nih.gov/articles/PMC5038401/

Systematic Review and Meta-Analysis of Doxycycline Efficacy ...

In a prospective study of rectal LGV treatment, 100 mg doxycycline twice daily for 7 days achieved a negative repeat chlamydia test result for only 15 (88%) of ...

5.

sciencedirect.com

sciencedirect.com/science/article/abs/pii/S0735675724002250

Doxycycline adherence for the management of Chlamydia ...

They reported that 90% of patients reported taking their doxycycline as directed, but only 16% achieved complete compliance according to the MEMS data [17].

6.

pubmed.ncbi.nlm.nih.gov

pubmed.ncbi.nlm.nih.gov/22431798/

Safety and efficacy of WC2031 versus vibramycin for the ...

Conclusions: WC2031 was noninferior to Vibramycin for uncomplicated urogenital chlamydia treatment, better tolerated, and demonstrated comparable safety. WC2031 ...

7.

clinicaltrials.gov

clinicaltrials.gov/study/NCT01113931

Treatment of Chlamydia Infection Comparing WC2031 ...

Evaluate the clinical efficacy and safety of WC2031 200 mg tablets taken orally once a day for 7 days versus Vibramycin (doxycycline) 100 mg capsules taken ...

8.

academic.oup.com

academic.oup.com/cid/article/55/1/82/317607

Safety and Efficacy of WC2031 Versus Vibramycin for the ...

Conclusions. WC2031 was noninferior to Vibramycin for uncomplicated urogenital chlamydia treatment, better tolerated, and demonstrated comparable safety. WC2031 ...

9.

nejm.org

nejm.org/doi/full/10.1056/NEJMoa1502599

Azithromycin versus Doxycycline for Urogenital Chlamydia ...

We conducted a randomized trial comparing oral azithromycin with doxycycline for the treatment of urogenital chlamydia infection among adolescents in youth ...