Testing a lower dose of an antibiotic for pneumonia caused by Pneumocystis
Compares a lower dose of trimethoprim-sulfamethoxazole with the standard dose in adults with Pneumocystis pneumonia.
Plain-language title generated from the registry record
Registry title: Low Dose Trimethoprim-Sulfamethoxazole for the Treatment of Pneumocystis Jirovecii Pneumonia
Key facts
- Where
- Montreal, CanadaSee the site
- Phase
- Phase 3
AI summary: who the study is looking for
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 a weakened immune system who have a proven or probable Pneumocystis jirovecii pneumonia (PCP) infection. It compares a low dose with the standard dose of trimethoprim-sulfamethoxazole.
- Age
- 18 Years to 100 Years
- Sex
- All sexes can join.
- Disease stage
- Proven or probable PCP, using an adapted version of the 2021 EORTC/MSGERC criteria. Seen in a day hospital or emergency department, or admitted to hospital.
- Earlier treatment
- People with more than 96 hours of any PCP therapy cannot join. People who took PCP prevention with TMP-SMX for 4 weeks or more at enrollment cannot join.
- Biomarker or test result
- Alanine aminotransferase must be below 5 times the upper limit of normal. Known G6PD deficiency or porphyria rules a person out.
Main reasons for not taking part
- Earlier severe reaction to TMP-SMX, any sulfa drug, or a component of the formulation
- Known pregnancy or breastfeeding
- Known G6PD deficiency or known porphyria
- Unable to give consent with no healthcare proxy, or refusal of consent
- Already enrolled before
Read by machine on 9 November 2026.
Could this be for you?
Answer for yourself. This is not a decision: only the study team can say whether you can take part.
- Are you between 18 and 100 years old?
Source: NCT04851015, who can take part
Where in Canada
- McGill university Health Centre (Royal victoria Hospital and Montreal General HospitalMontreal, CanadaTaking 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
- Todd C. Lee MD MPH FIDSA
- Trial code
- NCT04851015
- Record updated
- 20 February 2026
- Original description
Pneumocystis jirovecii pneumonia (PCP) is an opportunistic fungal infection of immunocompromised hosts which causes in significant morbidity and mortality. The current standard of care, trimethoprim-sulfamethoxazole (TMP-SMX) at a dose of 15-20 mg/kg/day of TMP, is associated with serious adverse events, including hypersensitivity reactions, drug-induced liver injury, cytopenia, and renal failure occurring among 20-60% of patients. The frequency of adverse events increases in a dose dependent manner and commonly limits the use of TMP-SMX.Read full original descriptionShow less
Low Dose Trimethoprim-Sulfamethoxazole for the Treatment of Pneumocystis Jirovecii Pneumonia
Pneumocystis jirovecii pneumonia (PCP) is an opportunistic fungal infection of immunocompromised hosts which causes in significant morbidity and mortality. The current standard of care, trimethoprim-sulfamethoxazole (TMP-SMX) at a dose of 15-20 mg/kg/day of TMP, is associated with serious adverse events, including hypersensitivity reactions, drug-induced liver injury, cytopenia, and renal failure occurring among 20-60% of patients. The frequency of adverse events increases in a dose dependent manner and commonly limits the use of TMP-SMX.
Reduced treatment doses of TMP-SMX for PCP reduced ADEs without mortality differences in a recent meta-analysis of observational studies. We therefore propose a Phase III randomized, placebo-controlled trial to directly compare the efficacy and safety of low dose (10 mg/kg/day of TMP) compared to the standard-of-care (15 mg/kg/day) among patients with PCP for the primary outcome of Win Ratio hierarchical composite of death, ECMO, invasive ventilation, grade 4 toxicity, non-invasive ventilation, change of therapy and length of stay.
Inclusion: 18 years or older; Immunocompromised (including but not limited to HIV, solid organ transplant, solid tumors, hematological stem cell transplant and malignancies, systemic diseases, chemotherapy, long term corticosteroid use, and immunosuppressive therapies, as well as primary immunodeficiencies; Presentation to a day hospital, emergency department, or admitted to hospital; Proven or probable diagnosis of PCP using an adapted version of the 2021 EORTC/MSGERC criteria.
Exclusion: Previous severe adverse reaction to TMP-SMX, any sulfa drug, or any component of formulation; More than 96 hours of any therapy for PCP; Previously enrolled; Hepatic impairment marked by alanine aminotransferase levels ≥5 times the upper limit of normal; Unable to provide informed consent and no available healthcare proxy (with ethics approval for deferred consent in cases of critical illness); refusal of consent; no reliable means of outpatient contact (telephone/email/text); Compliant with PCP prophylaxis for ≥4 weeks with TMP-SMX at enrollment; Known G6PD deficiency; Known diagnosis of porphyria; Known pregnancy or breastfeeding (as per Health Canada).