Skip to content
Clinical Trials – home

Rare diseases

Investigational molecules

Locations

Our offerNewsroom

Not yet recruiting

Efficacy of daily high‑dose sulfamethoxazole‑trimethoprim prophylaxis versus low‑dose on bacterial infections in kidney transplant recipients

Verified siteRegistered drugNo placebo
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

What is this trial about?

A plain-language summary of the goals, design and what participants do

The study focuses on people who have undergone a kidney transplant and are at risk for a bacterial infection. The medication being examined is cotrimoxazole, an oral antibiotic that contains two active ingredients and is taken as a single tablet each day. Two different strengths are compared: a high dose (800 mg/160 mg) and a low dose (400 mg/80 mg).

The purpose is to determine which dose more effectively prevents infection during the first six months after transplantation. Participants are randomly assigned to receive either the high dose or the low dose daily, beginning shortly after the transplant, and they are observed for a six‑month period.

During the follow‑up, any episodes of infection, hospital stays for infection, and serious health problems are recorded. Blood samples are taken to measure drug levels and to perform a PCR test—a laboratory technique that detects tiny pieces of DNA to assess viral activity. The study also monitors side effects and any issues affecting the transplanted kidney.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Randomization and Assignment to a Treatment Group

    After joining the study, you will be randomly placed into one of two groups. One group receives a high dose of cotrimoxazole (800 mg sulfamethoxazole / 160 mg trimethoprim) and the other group receives a low dose (400 mg sulfamethoxazole / 80 mg trimethoprim). This assignment determines which medication you will take for the next six months.

  2. Step 2

    Start of Daily Medication

    You will begin taking the assigned tablet by mouth once each day. The high‑dose tablet contains 800 mg of sulfamethoxazole and 160 mg of trimethoprim; the low‑dose tablet contains 400 mg of sulfamethoxazole and 80 mg of trimethoprim. The medication is taken for a total of six months after your kidney transplant.

  3. Step 3

    Consistent Daily Administration

    Take the tablet with a glass of water, preferably at the same time each day. Maintaining a regular schedule helps keep the drug level steady in your body.

  4. Step 4

    First Follow‑Up Visit (Month 1)

    One month after starting the medication, you will attend a clinic visit. The healthcare team will ask about any signs of bacterial infection, check for side effects, and perform a blood draw. The blood sample is used for a TTV PCR test (a laboratory test that measures a virus often present in the blood) and for measuring the amount of cotrimoxazole in your bloodstream.

  5. Step 5

    Ongoing Monitoring Between Visits

    During the six‑month period, you should report any fever, pain, swelling, cough, urinary problems, or other symptoms that could indicate an infection. You should also inform the study team if you need to be hospitalized for an infection or if you experience any serious side effects.

  6. Step 6

    Second Follow‑Up Visit (Month 6)

    At six months, you will return for a final clinic visit. The team will repeat the blood tests, including another TTV PCR, and will collect additional blood samples to assess the minimum (Cmin) and maximum (Cmax) drug concentrations as well as the overall exposure (AUC). A stool sample may be collected to study the effect of the medication on gut bacteria.

  7. Step 7

    Final Assessment and Study Completion

    After the six‑month visit, the study will evaluate whether you experienced any bacterial infections, whether any infection required hospitalization, and whether any serious or non‑serious adverse reactions occurred. The results will also include information on graft loss, death, and the causes of any adverse events.

Who can join the trial?

5 criteria

  • Be at least 18 years old.
  • Have a kidney transplant (the first time you receive a new kidney) and not a repeat transplant.
  • Give free and informed consent – you agree to join the study after understanding what it involves.
  • Be covered by a Social Security health plan (your health insurance must be part of the national system).
  • Be able to understand what the study is about, why it is being done, and what you will need to do during the study.

Who cannot join the trial?

14 criteria

  • Very low kidney function (eGFR below 15 mL/min) – eGFR is a lab test that estimates how well the kidneys filter blood; a result under 15 means the kidneys are working at a severely reduced level.
  • Recent use of cotrimoxazole for 14 days or more in the past three months – taking the study medication (or a similar drug) for two weeks or longer within the last three months.
  • Taking certain other medicines at the same time – specifically the drugs phenytoin or methotrexate, which can interact with the study medication.
  • Allergy to any inactive ingredients (excipients) in the study drug – a hypersensitivity reaction to substances used to make the tablet, not the active drug itself.
  • Being a close relative of the study investigators or team members – family members of the doctors or staff conducting the trial.
  • Being in jail, under legal guardianship, or otherwise deprived of freedom by a court decision – includes people who are incarcerated or have a legal protector.
  • Severe liver disease – either very serious damage to liver tissue or a blood test called alanine aminotransferase (ALT) that is more than five times higher than the normal upper limit.
  • Currently enrolled in another clinical trial or still in the waiting period after finishing a previous study – participation in any other research study at the same time.
  • Pregnancy or breastfeeding – includes women who are pregnant, may become pregnant, or are nursing a baby; they must have a negative pregnancy test and use effective birth control.
  • Having had a previous solid organ transplant other than the kidney – such as a heart, liver, or lung transplant performed before.
  • Receiving a combined transplant (kidney plus another organ at the same time) – having both a kidney and another organ transplanted together.
  • Allergy to the study drug or any related sulfa drugs (sulfamides) – a known hypersensitivity or previous allergic reaction to these medications.
  • History of G6PD deficiency – a genetic condition that can cause red blood cells to break down when exposed to certain medications.
  • Known diagnosis of porphyria – a rare disorder that affects the skin or nerves and can be triggered by some medicines.
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

We usually reply within a few days

Verified sites

All sites with verified contact details – recruitment status may not be available; ask directly

Trial locations

Where you can join this trial

Countries are shaded by recruitment status. Click a recruiting country to ask about joining there.

Not yet recruiting
Not finding your country?

Not sure what to do next?

Joining a clinical trial can seem overwhelming. We guide you step by step, so you know exactly what to expect and how we support you through the process.

See the full process and FAQ

Investigated drugs

  • BACTRIM FORTE

    is a tablet taken by mouth that contains two antibiotics, sulfamethoxazole and trimethoprim. In this study it is used as the high‑dose test medication to see if it can prevent bacterial infections after a kidney transplant.

  • COTRIMOXAZOLE TEVA 800 mg/160 mg

    is another oral tablet that also combines sulfamethoxazole and trimethoprim. It is given as the high‑dose test treatment in the trial, aiming to reduce the chance of bacterial infections in transplant patients.

  • Sulfamethoxazole AND trimethoprim

    (with added bromhexine hydrochloride and tolu balsam) is an oral tablet that includes the same two antibiotics, sulfamethoxazole and trimethoprim, plus ingredients that help clear mucus. This product is used as a high‑dose test option to evaluate its ability to prevent infections after kidney transplantation.

  • BACTRIM

    is an oral tablet that contains sulfamethoxazole and trimethoprim at a lower dose. In the trial it serves as a comparator, allowing researchers to compare the effect of a lower dose of the same antibiotics with the high‑dose regimen.

  • Bactrim 400 mg/80 mg

    is a tablet taken by mouth that also provides the combination of sulfamethoxazole and trimethoprim at a lower dose. It is used as another comparator medication to help determine whether the higher dose offers better protection against bacterial infections after a kidney transplant.

What is already known about the treatment

  • BACTRIM FORTE

    It is taken by mouth as a tablet that contains 800 mg sulfamethoxazole and 160 mg trimethoprim. The drug is a well‑known antibiotic that is widely used and described in medical literature. It is mainly prescribed to treat and prevent bacterial infections, especially in people with weakened immune systems such as kidney‑transplant patients. It works by stopping bacteria from making folic acid, which they need to grow, and belongs to the class of sulfonamide‑trimethoprim combinations.

  • COTRIMOXAZOLE TEVA

    This product is also an oral tablet with the same 800 mg/160 mg dose of sulfamethoxazole and trimethoprim. It is an established medication that appears in many guidelines for infection prevention after organ transplantation. It is used to prevent bacterial infections in transplant recipients and other high‑risk groups. Like other cotrimoxazole products, it blocks two steps in bacterial folic‑acid synthesis, classifying it as a sulfonamide‑trimethoprim antibiotic.

  • Sulfamethoxazole AND trimethoprim with bromhexine hydrochloride and tolu balsam

    This combination is taken orally as a tablet that contains sulfamethoxazole, trimethoprim, plus the cough‑relieving agent bromhexine and a soothing ingredient called tolu balsam. The antibiotic part is well known and widely studied, while the added ingredients are used to help clear mucus and calm irritation. It is intended for the treatment of bacterial infections together with relief of respiratory symptoms. The medication works by the same folic‑acid blockage of the bacteria and is classified as a sulfonamide‑trimethoprim drug with an added mucolytic component.

Investigated diseases

  • Bacterial infection

    A bacterial infection occurs when bacteria enter body tissues and begin to multiply, causing inflammation and symptoms such as fever, pain, or swelling. The infection often starts in a localized area and can spread to nearby tissues or enter the bloodstream if not controlled. Early signs may include redness, warmth, and pus formation at the entry site. As the bacterial load grows, the immune response intensifies, leading to more noticeable systemic signs. The course of the infection depends on the type of bacteria and the host’s immune defenses.

  • Kidney transplant

    A kidney transplant is the surgical placement of a healthy donor kidney into a person whose own kidneys no longer function adequately. After surgery, the new kidney begins to filter blood, produce urine, and help regulate fluid and electrolyte balance. Over time the transplanted kidney adapts to the recipient’s body, and its function is monitored through blood and urine tests. The organ may experience gradual changes such as reduced filtering capacity or inflammation, which are tracked during follow‑up visits. The condition persists as long as the transplanted kidney remains functional.

Trial detailsLast updated 11 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2026-526183-20-00Protocol codeAPHP240951Estimated enrolment1 400 patientsSponsorAssistance Publique Hopitaux De Paris

sourced from the EU Clinical Trials Register and site verification

Want to learn more about this trial or check if you can participate?

Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.