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Study on the Effectiveness of Atovaquone and Proguanil for Malaria Prevention in Healthy Volunteers

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What is this study about?

This clinical trial is focused on studying the disease known as malaria, which is caused by a parasite that infects red blood cells. The study will use a treatment called Malarone, which is a combination of two active substances: proguanil hydrochloride and atovaquone. These substances are taken in the form of a film-coated tablet. Additionally, the study involves the use of PfSPZ Challenge (NF54), which is a solution for injection containing the malaria parasite Plasmodium falciparum, strain NF54, sporozoites. This is used to expose participants to malaria in a controlled way.

The purpose of the study is to evaluate how effective a weekly dose of the oral medication atovaquone-proguanil is in preventing malaria in healthy volunteers who have not been exposed to the disease before. Participants will receive either the medication or a placebo and will be exposed to the malaria parasite through an intravenous injection. The study will monitor the participants for a period to see if the medication can prevent the development of malaria.

Throughout the study, participants will be closely observed to ensure their safety and to check for any side effects related to the medication. The main goal is to determine if the medication can protect against malaria by preventing the increase of parasites in the blood. The study will also look at any side effects that occur from the time the medication or placebo is taken until the end of the study. This research aims to provide valuable information on the prevention of malaria using this specific medication regimen.

1 joining the study

Upon joining the study, you will be required to provide written informed consent. This means you agree to participate in the study and understand what it involves.

You will need to answer all questions on the informed consent quiz correctly to ensure you understand the study requirements.

2 medication administration

You will receive a medication called atovaquone-proguanil in the form of a film-coated tablet. The dosage is 250 mg of atovaquone and 100 mg of proguanil.

This medication will be taken orally once a week. The duration of this administration will be specified by the study team.

3 exposure to malaria

You will be exposed to malaria through an intravenous injection of a solution called PfSPZ Challenge (NF54). This is a controlled exposure to malaria parasites to test the effectiveness of the medication.

4 monitoring and follow-up

After the exposure, your health will be closely monitored. This includes regular check-ups and blood tests to ensure your safety and to measure the effectiveness of the medication.

You will be reachable by mobile phone 24/7 during the period following the malaria exposure to ensure prompt communication if needed.

5 completion of the study

The study will conclude after a specified period, and you will be informed about the results and any further steps if necessary.

You will be required to refrain from donating blood during the study and for a period after its completion, as per local and national guidelines.

Who Can Join the Study?

  • Healthy adults who have never had malaria, aged 18 to 40 years.
  • Willing to take the study medication or a placebo at the scheduled times and a treatment for malaria if needed.
  • Must answer all questions correctly on a quiz about the study’s informed consent.
  • Able and willing, in the opinion of the study doctor, to follow all study requirements.
  • Agree to let the study doctors discuss their medical history with their regular doctor if needed.
  • Live within a one-hour travel distance to the study center.
  • Women must agree to use a reliable form of birth control during the study.
  • Weigh more than 40 kg (about 88 pounds) and have a Body Mass Index (BMI) between 19 and 30. BMI is a measure of body fat based on height and weight.
  • Agree not to donate blood during the study and for a period after the study, according to local and national guidelines.
  • Provide written consent to receive a malaria challenge as part of the study. Consent means agreeing to participate after understanding the study details.
  • Must be reachable by mobile phone at all times during the malaria challenge period.

Who Cannot Join the Study?

  • People who have had a previous allergic reaction to the study medication cannot participate.
  • Individuals with a history of severe allergic reactions to any medication are excluded.
  • Participants with any current or past medical condition that could interfere with the study results are not eligible.
  • Pregnant or breastfeeding women cannot take part in the study.
  • Anyone who has participated in another clinical trial within the last 30 days is not allowed to join.
  • Individuals with a history of drug or alcohol abuse in the past year are excluded.
  • People with a compromised immune system, which means their body’s defense against infections is weakened, cannot participate.
  • Participants who are unable to comply with the study procedures or follow-up visits are not eligible.
  • Anyone with a known infection or disease that could affect the study outcomes is excluded.
  • Individuals taking medications that could interfere with the study drug are not allowed to join.

Where you can join this trial?

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Verified Sites

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Other Sites

Site Name City Country Status
Universitaetsklinikum Tuebingen AöR Tuebingen Germany

Want to learn more about this study or check if you can participate? Contact us.

Trial status

Country Status Recruitment Start
Germany Germany
Recruiting
13.11.2025

Trial locations

Investigated drugs:

Atovaquone-Proguanil is a medication used to prevent malaria, a disease caused by parasites that are transmitted to people through the bites of infected mosquitoes. In this clinical trial, the medication is being tested to see how well it works when taken once a week by healthy volunteers who do not have immunity to malaria. The goal is to see if this medication can effectively prevent malaria infection when the volunteers are exposed to the malaria parasite in a controlled setting. Atovaquone-Proguanil works by stopping the growth of the parasites in the blood, which helps prevent the disease from developing.

Malaria – Malaria is an infectious disease caused by Plasmodium parasites, which are transmitted to humans through the bites of infected Anopheles mosquitoes. Once inside the human body, the parasites travel to the liver, where they mature and reproduce. After a period of incubation, the parasites enter the bloodstream and infect red blood cells, leading to symptoms such as fever, chills, and flu-like illness. The disease progresses in cycles of fever and chills as the parasites continue to multiply and destroy red blood cells. If left unchecked, malaria can cause severe complications due to the destruction of red blood cells and blockage of small blood vessels. The disease is most prevalent in tropical and subtropical regions where the mosquito vectors thrive.

Trial ID:
2024-518884-36-00
Protocol code:
SPARE
Trial Phase:
Therapeutic exploratory (Phase II)

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