Using doxycycline to improve lung function in tuberculosis patients

Doxycycline Host-directed Therapy to Improve Lung Function and Decrease Tissue Destruction in Pulmonary Tuberculosis: A Phase III Randomized Control Trial (Doxy-TB)

Phase 3 Interventional National University Hospital, Singapore · NCT05473520

This study is testing if adding doxycycline to the standard treatment for tuberculosis can help improve lung function and reduce damage in patients with lung infections.

Quick facts

PhasePhase 3
Study typeInterventional
Enrollment150 (estimated)
Ages21 Years and up
SexAll
SponsorNational University Hospital, Singapore Academic / other
Locations6 sites (Kota Kinabalu, Sabah and 5 other locations)
Trial IDNCT05473520 on ClinicalTrials.gov

What this trial studies

This Phase 3 double-blind randomized-controlled trial investigates the effectiveness of adjunctive doxycycline therapy in improving lung function and reducing tissue damage in patients with pulmonary tuberculosis (PTB). A total of 150 participants will receive either doxycycline or a placebo alongside standard TB treatment for 8 weeks, followed by a 4-month follow-up. The study will assess lung function through forced expiratory volume tests and analyze sputum and blood samples to evaluate the impact of doxycycline on inflammation and tissue destruction. The goal is to determine if doxycycline can decrease pulmonary impairment after tuberculosis treatment.

Who should consider this trial

Good fit: Ideal candidates are adults aged 21 and above who are starting standard TB treatment and have confirmed pulmonary TB with cavities.

Not a fit: Patients with HIV co-infection, previous pulmonary TB, or severe pre-existing lung diseases will not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could significantly improve lung function and quality of life for patients recovering from tuberculosis.

How similar studies have performed: Previous studies have shown promising results with doxycycline in reducing inflammation and tissue damage in TB patients, indicating potential for success in this approach.

Eligibility criteria

Show full inclusion / exclusion criteria
The recruitment target would be 150 patients, with 75 in each arm

Inclusion criteria: Patients should meet all criteria:

1. Aged 21 years and above
2. Patients receiving ≤ 7 days of TB treatment or about to start standard combination TB treatment
3. Confirmed pulmonary TB with positive acid-fast bacilli smear and/or positive nucleic acid amplification test (NAAT) and/or TB culture results
4. CXR demonstrating pulmonary involvement with cavity or cavities
5. Able to provide informed consent

Exclusion criteria:

1. HIV co-infection
2. Previous pulmonary TB
3. Severe, pre-existing lung disease such as pulmonary fibrosis, bronchiectasis, COPD and lung cancer
4. Pregnant or breast feeding
5. Allergies to tetracyclines
6. Patients on retinoic acid, neuromuscular blocking agents and pimozide which may increase risk of drug toxicity
7. Autoimmune disease and/or on systemic immunosuppressants
8. Use of any investigational or non-registered drug, vaccine or medical device other than the study drug within 182 days preceding dosing of study drug, or planned use during the study period
9. Enrolment in any other clinical trial involving a systemic drug or intervention involving the lung
10. Evidence of severe depression, schizophrenia or mania
11. ALT \> 3 times upper limit of normal
12. Creatinine \> 2 times upper limit of normal
13. Principal investigator assessment of lack of willingness to participate and comply with all requirements including follow-up of the protocol, or identification of any factor felt to significantly increase the participant's risk of suffering an adverse outcome

Where this trial is running

Kota Kinabalu, Sabah and 5 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions TuberculosisAcute Coronary SyndromePulmonary Hypertension
Last reviewed 2026-06-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.