Tests doxycycline added to standard treatment for lung tuberculosis
Tests doxycycline alongside standard treatment in adults with pulmonary tuberculosis.
Key facts
- Who runs it
- National University Hospital, Singapore
- Where
- Singapore, SingaporeSee the 2 sitesAlso in 1 other country, 4 sites
- Trial code
- Registry title
- Doxycycline Host-directed Therapy to Improve Lung Function and Decrease Tissue Destruction in Pulmonary Tuberculosis
- Status
- Recruiting
- Phase
- Phase 3
- People taking part
- 150 people, planned
- Started
- 24 May 2023
- Expected to end
- 31 Jan 2030
- Type of study
- Interventional, 2 groupsOne group gets a placebo (a dummy treatment), for comparison.
- Treatments tested
- Doxycycline
- Placebo
- Record updated
- 9 June 2026
Who can take part
AI summary
From the trial's eligibility criteria. Machine-read from the registry text on this page, so it can be wrong. The registry text below and the trial team decide who can take part.
The trial is looking for adults with newly diagnosed lung tuberculosis who have cavities in the lungs. It tests doxycycline added to standard TB treatment, compared with placebo.
- Age
- 21 years and older
- Sex
- All sexes can join
- Disease stage
- Lung tuberculosis confirmed by a positive smear, NAAT or culture test, with one or more cavities seen on chest X-ray
- Earlier treatment
- Has had 14 days or less of TB treatment, or is about to start standard combination TB treatment. No previous lung TB.
- Biomarker or test result
- Positive acid-fast bacilli smear and/or positive nucleic acid amplification test (NAAT) and/or positive TB culture
Main reasons for not taking part
- HIV co-infection
- Previous pulmonary TB
- Severe lung disease such as pulmonary fibrosis, bronchiectasis, COPD or lung cancer
- Pregnant or breast feeding
- Allergy to tetracyclines
The registry criteria, word for word
Show all 19 criteriaShow less
Who can take part
- Aged 21 years and above
- Patients receiving ≤ 14 days of TB treatment or about to start standard combination TB treatment
- Confirmed pulmonary TB with positive acid-fast bacilli smear and/or positive nucleic acid amplification test (NAAT) and/or TB culture results
- CXR demonstrating pulmonary involvement with cavity or cavities
- Able to provide informed consent
Who cannot take part
- Previous pulmonary TB
- Patients on retinoic acid, neuromuscular blocking agents and pimozide which may increase risk of drug toxicity
- 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
- Enrolment in any other clinical trial involving a systemic drug or intervention involving the lung
- HIV co-infection
- Severe, pre-existing lung disease such as pulmonary fibrosis, bronchiectasis, COPD and lung cancer
- Allergies to tetracyclines
- Autoimmune disease and/or on systemic immunosuppressants
- ALT > 3 times upper limit of normal
- Creatinine > 2 times upper limit of normal
- Pregnant or breast feeding
- Evidence of severe depression, schizophrenia or mania
- 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
Other criteria
- The recruitment target would be 150 patients, with 75 in each arm
Where in Singapore
Also in 1 other country, 4 sites
- National University HospitalSingapore, SingaporeContact: Catherine ONG, MRCP PhDTaking people
- TB Control UnitSingapore, SingaporeContact: Shera Tan, DrTaking people
About the trial
What the trial wants to find out
Tuberculosis (TB) is a global pandemic that despite successful treatment and bacterial eradication can cause chronic ill health, such as pulmonary impairment after tuberculosis (PIAT) and cardiovascular disease (CVD). A recent Phase 2b double-blind randomised-controlled clinical trial shows that adjunctive doxycycline therapy is safe, accelerates resolution of inflammation, suppresses tissue damaging enzyme activity and decreases pulmonary cavity volume (1). We aim to determine if adjunctive doxycycline can reduce PIAT and improve cardiovascular outcomes in a fully powered Phase III trial of 8 weeks of adjunctive doxycycline alongside standard pulmonary TB (PTB) treatment.
Read full original descriptionShow less
The investigators hypothesize that doxycycline inhibits tissue destruction in patients with PTB and thereby leads to improved lung function after treatment.
Specific aims
1. To assess improvement in lung function as measured by forced expiratory volume (FEV1) predicted in PTB patients given doxycycline versus placebo. 2. To investigate whether doxycycline will hasten the resolution of pulmonary cavities measured by CT thorax 3. To investigate whether doxycycline can suppress inflammatory markers including matrix metalloproteinases 4. To investigate whether doxycycline can accelerate time to sputum conversion 5. To evaluate the effect of doxycycline on cardiovascular outcomes such as the incidence of acute coronary syndrome (ACS) and pulmonary hypertension 6. To investigate whether doxycycline improves TB drug concentrations in sputum and plasma. 7. To assess the safety profile of doxycycline with concurrent standard anti-tuberculous treatment.
The 2 groups in the trial
- Doxycycline + standard anti-tuberculous treatmentTreatment being tested
Doxycycline 100 mg twice daily with once daily anti-tuberculous treatment comprising of rifampicin 10 mg/kg, isoniazid 5 mg/kg, ethambutol 15 - 20 mg/kg, ± pyrazinamide 25 mg/kg and pyridoxine 10-50 mg per day according to managing physicians' discretion. Where needed, the drugs will be adjusted according to renal function. These will be given daily for 8 weeks. Subsequently doxycycline will be ceased and patients are to continue with their standard anti-tuberculous treatment and duration according to their managing physician
Treatment: Doxycycline
- Placebo + standard anti-tuberculous treatmentPlacebo, for comparison
Placebo twice daily with once daily anti-tuberculous treatment comprising of rifampicin 10 mg/kg, isoniazid 5 mg/kg, ethambutol 15-20 mg/kg, ± pyrazinamide 25 mg/kg and pyridoxine 10-50 mg per day according to managing physicians' discretion. Where needed, the drugs will be adjusted according to renal function. These will be given daily for 8 weeks. Subsequently placebo will be ceased and patients are to continue with their standard anti-tuberculous treatment and duration according to their managing physician.
Treatment: Placebo
Questions to ask the study team
- How often do I need to come in, and for how long each time?
- Are travel costs paid?
- Can I keep my own doctor?
- What happens if I want to stop?
Contact the study team: see the registry record → Contacts and Locations
Print a page for my doctorData and sources
- Registry record
- Listed on ClinicalTrials.gov.
- Official title
- Doxycycline Host-directed Therapy to Improve Lung Function and Decrease Tissue Destruction in Pulmonary Tuberculosis: A Phase III Randomized Control Trial (Doxy-TB)
- Plain-language title
- Tests doxycycline added to standard treatment for lung tuberculosisGenerated from the registry record. The registry title is the official one.
- AI summary
- From the trial's eligibility criteria. Read by machine on 12 November 2026.
- Record updated
- 9 June 2026