RecruitingPHASE3INTERVENTIONAL

Low Dose Trimethoprim-Sulfamethoxazole for the Treatment of Pneumocystis Jirovecii Pneumonia

This study is investigating a common lung infection called Pneumocystis pneumonia (PCP) which mainly affects people with weakened immune systems, such as those with HIV or who have had organ transplants. The current treatment uses a medicine called trimethoprim-sulfamethoxazole (TMP-SMX), but at the usual dose, it can cause significant side effects like allergic reactions or kidney problems in many patients. Researchers want to see if using a lower dose of this medicine is just as good at treating PCP but causes fewer of these unpleasant side effects. This could make treatment much easier to tolerate for patients. The study will compare patients receiving the standard dose with those receiving a lower dose to see which is safer and more effective.

At a glance

Status

Recruiting

Phase

PHASE3

Sponsor

Todd C. Lee MD MPH FIDSA

Enrolment target

416

Start

28 Nov 2025

Estimated completion

31 Dec 2030

Pneumocystis Pneumocystis Pneumonia Pneumocystis Jirovecii Infection Pneumocystis Infections Pneumocystis Carinii Infection Pneumocystosis; Pneumonia (Etiology)Pneumocystis Carinii; Infection, Resulting From HIV Disease Pneumocystosis Associated With AIDS

What is this study about?

This study is about a lung infection called Pneumocystis pneumonia (PCP). This infection is caused by a tiny fungus and mainly affects people whose immune systems are not working as well as they should be. This can include people living with HIV, those who have had organ or stem cell transplants, individuals undergoing certain cancer treatments, or people taking medicines that suppress their immune system.

The usual treatment for PCP is a medicine called trimethoprim-sulfamethoxazole, often shortened to TMP-SMX. While this medicine is effective, higher doses can cause quite a few side effects, such as allergic reactions, liver problems, issues with blood cells, or kidney difficulties. These side effects can be serious and affect a large number of patients, sometimes making it difficult for them to continue treatment.

Researchers want to find out if a lower dose of TMP-SMX is just as good at treating PCP but causes fewer of these side effects. Previous research has suggested that lower doses might be effective with fewer problems, but a full study is needed to be sure. This study will involve comparing the standard dose with a lower dose to see which approach is better for patients in terms of successfully treating the infection and reducing the chances of side effects.

Key takeaways

PCP is a serious lung infection for people with weak immune systems.
The standard treatment (TMP-SMX) can have significant side effects.
This study compares a lower dose of TMP-SMX against the standard dose.
The goal is to find out if a lower dose is as effective but has fewer side effects.
Participants will be closely monitored for treatment success and side effects.

Who may be eligible?

To join this study, you need to be 18 years old or older and have a weakened immune system. This could be due to conditions like HIV, having had an organ transplant, certain cancers, taking medicines that suppress your immune system (like steroids), or other immune problems. You also need to have been diagnosed with PCP, which means you're being seen at a hospital or emergency department for the infection.

However, you can't take part if you've had a serious allergic reaction to TMP-SMX or similar medicines in the past. If you've been taking TMP-SMX to prevent PCP for a month or more, or if you've already had more than four days of treatment for PCP, you also won't be able to join. Other reasons you might not be able to participate include severe liver problems, a specific genetic condition called G6PD deficiency, or a rare blood disorder called porphyria.

Also, if you are pregnant or breastfeeding, you won't be able to join. Finally, if you're unable to understand and agree to take part, or if you don't have a reliable way for the research team to contact you, you won't be eligible.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you 18 years old or older?
Do you have a weakened immune system and a diagnosis of PCP?
Have you *not* had a severe allergic reaction to TMP-SMX or similar drugs before?
Have you had less than 4 days of PCP treatment so far?
Are you *not* pregnant or breastfeeding, and do you *not* have severe liver problems or certain genetic conditions?

Answer every question to see your result.

What does participation involve?

If you decide to take part in this study, you will be randomly assigned to receive either the standard dose of trimethoprim-sulfamethoxazole (the medicine for PCP) or a lower dose. You will receive this medication as part of your treatment for PCP. The study team will closely monitor your health to see how well the treatment is working and if you experience any side effects.

This will involve regular check-ups, blood tests, and other assessments during your treatment period in the hospital and potentially after you go home. The exact number of visits and tests will depend on your individual treatment plan and how you respond. The doctors will track things like whether the infection clears up, if you need other medical support like breathing assistance, how long you stay in hospital, and any side effects you might have. The total duration of your participation will depend on the length of your treatment for PCP and follow-up.

Potential risks and benefits

Taking part in this study might offer the benefit of potentially receiving a dose of medicine that could lead to fewer side effects, while still treating your PCP effectively. However, there's also a chance you might experience side effects with either dose, as this is a known risk of the medication. The study aims to gather more information to help future patients. You have the right to withdraw from the study at any time, for any reason, without it affecting your medical care.

Locations (1)

McGill University Health Centre (Royal Victoria Hospital and Montreal General Hospital)
Verified postcode
Montreal, Canada· Recruiting

Common questions

What is Pneumocystis pneumonia (PCP)?

PCP is a serious lung infection caused by a fungus, usually affecting people with weakened immune systems.

What is trimethoprim-sulfamethoxazole (TMP-SMX)?

It's a common antibiotic medicine used to treat PCP and other infections.

Why are doctors studying a lower dose?

The usual dose can cause many side effects, so researchers want to see if a lower dose works just as well with fewer problems.

Who can join this study?

Adults over 18 with a weakened immune system and a new diagnosis of PCP, who meet certain health criteria, might be able to join.

Will I know which dose I'm getting?

No, you will be randomly assigned to either the standard or lower dose; this helps ensure the study results are fair.

How to find out more

Babykumari Chitramuthu, PhD

babykumari.chitramuthu@muhc.mcgill.ca 514-934-1934 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.