Tests doxycycline added to standard treatment for lung tuberculosis
Tests doxycycline alongside standard treatment in adults with pulmonary tuberculosis.
Plain-language title generated from the registry record
Registry title: Doxycycline Host-directed Therapy to Improve Lung Function and Decrease Tissue Destruction in Pulmonary Tuberculosis
Key facts
- Where
- Singapore, SingaporeSee the 2 sites
- Phase
- Phase 3
Where in Singapore
- National University HospitalSingapore, SingaporeTaking people
- TB Control UnitSingapore, SingaporeTaking people
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?
Trial details
- Who runs it
- National University Hospital, Singapore
- Trial code
- NCT05473520
- Record updated
- 9 June 2026
- Original description
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
Doxycycline Host-directed Therapy to Improve Lung Function and Decrease Tissue Destruction in Pulmonary Tuberculosis: A Phase III Randomized Control Trial (Doxy-TB)
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.
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.
Inclusion: 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.
Exclusion: 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.
The recruitment target would be 150 patients, with 75 in each arm.