A Study of Sonlicromanol for Reducing Fatigue in Patients with Long COVID

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What is this study about?

This study looks at long COVID, a condition where people continue to have symptoms for more than six months after being infected with the virus that causes COVID-19. Common problems include severe tiredness, difficulties with physical activity, and trouble with thinking and memory. The study will test a medicine called Sonlicromanol, also known by its code name KH176, which is given as a tablet. Some people in the study will receive the actual medicine while others will receive placebo tablets that look the same but contain no active medicine.

The purpose of the study is to see if Sonlicromanol can reduce the severe tiredness that people with long COVID experience after 13 weeks of treatment. The medicine is taken by mouth and the highest daily amount given will be 180 milligrams. The treatment period will last for 13 weeks, which is about three months.

During the study, participants will be checked at different times to see how they are doing. The main focus will be on measuring tiredness levels at week 13 using a specific questionnaire. The study will also look at other aspects of health including overall quality of life, thinking abilities, and physical strength. These measurements will be done at the start of the study and then again at weeks 4, 8, and 13 using various questionnaires and physical tests such as grip strength measurements and thinking tests. The study is designed so that neither the participants nor the doctors know who is receiving the actual medicine and who is receiving the placebo until the study is finished.

1 Beginning of treatment period

After joining the study, you will begin the treatment phase. This is a randomized, double-blind, placebo-controlled trial, which means you will be assigned by chance to receive either the active medication or a placebo, and neither you nor your doctor will know which one you are receiving.

The study medication is called sonlicromanol, which comes in tablet form for buccal use (placed in the mouth between the cheek and gum to dissolve).

If you are assigned to the placebo group, you will receive tablets that look identical but contain no active ingredient.

2 Week 4 assessment

At week 4 of the treatment period, your condition will be evaluated.

Your fatigue symptoms will be assessed, along with various aspects of your quality of life and physical functioning.

You will complete questionnaires including the SF-36 (a measure of overall health and quality of life) and the PROMIS cognitive function 8a score (which assesses your thinking and memory abilities).

Physical tests will be performed, including the Repeated Handgrip Strength test (measuring how strong your hand grip is over multiple attempts) and the Amsterdam Cognition Scan (evaluating your cognitive abilities).

3 Week 8 assessment

At week 8 of the treatment period, another evaluation will take place.

The same assessments performed at week 4 will be repeated to track changes in your condition.

This includes completing the SF-36 questionnaire and the PROMIS cognitive function 8a score.

Physical measurements will again include the Repeated Handgrip Strength test and the Amsterdam Cognition Scan.

4 Week 13 final assessment

At week 13, the final assessment of the treatment period will occur.

Your fatigue symptoms will be measured using the FAS (Fatigue Assessment Scale), which is the main outcome the study is designed to evaluate.

All other assessments will be repeated, including the SF-36 questionnaire, the PROMIS cognitive function 8a score, the Repeated Handgrip Strength test, and the Amsterdam Cognition Scan.

This final evaluation will help determine whether the treatment has been effective in reducing post-COVID related fatigue and improving other symptoms.

5 End of study participation

After the week 13 assessment, your active participation in the study will be complete.

The total duration of your involvement in the treatment phase will be approximately 13 weeks.

Who Can Join the Study?

You must be between 18 and 65 years old, any gender
You must have a confirmed diagnosis of long COVID (also called post-COVID) made by two experienced doctors
You must have a history of SARS-CoV-2 infection (the virus that causes COVID-19)
Your symptoms must have started after your COVID-19 infection and continued for more than 6 months
You must experience post exertional malaise, which means you feel worse after physical or mental activity, as measured by a specific questionnaire
You must have been healthy with no symptoms before your COVID-19 infection was confirmed by laboratory testing
Your Bell’s functionality score must be between 20% and 70%. This score measures how well you can function in daily activities, with lower numbers meaning more difficulty
You must not have been hospitalized during your initial COVID-19 infection
You must be able and willing to sign a consent form before any study tests begin
You must be able to attend all study appointments at the scheduled times
The study doctor must believe you can follow the study rules and requirements for the entire length of the study
If you exercise regularly, you must have kept the same exercise routine for at least 4 weeks before joining the study and continue this routine throughout the study
If you are a woman who can become pregnant, you must use highly effective birth control methods during the study. Acceptable methods include complete abstinence from sexual intercourse, hormonal birth control pills or other hormonal methods that prevent ovulation (release of eggs), an intrauterine device (IUD) which is a small device placed in the uterus, permanent sterilization surgery performed at least six weeks before the study, or having a partner who has had a vasectomy (a permanent male sterilization procedure) confirmed by a doctor

Who Cannot Join the Study?

No exclusion criteria have been specified for this clinical trial in the provided information.

Where you can join this trial?

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Other Sites

Site Name	City	Country	Status
Algcxyvqq Usm	Amsterdam	The Netherlands

Trial status

Country	Status	Recruitment Start
The Netherlands	Recruiting	01.11.2025

Trial locations

Investigated drugs:

SONLICROMANOL HYDROCHLORIDE

Sonlicromanol is an investigational medication being tested in this study to see if it can help reduce fatigue in people who continue to experience tiredness after having COVID-19. This medicine is being compared against a placebo to determine if it is effective in improving energy levels and reducing the feeling of exhaustion that some patients experience following their COVID-19 infection.

Long COVID – Long COVID is a condition that occurs when symptoms persist for weeks or months after the initial COVID-19 infection has resolved. People with this condition experience ongoing health problems that can affect multiple parts of the body. Common symptoms include persistent fatigue, difficulty thinking clearly, and reduced physical strength. The condition can impact daily activities and quality of life as symptoms may fluctuate over time. Various body systems can be affected, including physical energy levels and cognitive abilities. The condition typically develops following a COVID-19 infection and continues beyond the expected recovery period.

Trial ID:

2025-521866-92-01

Trial Phase:

Therapeutic exploratory (Phase II)

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A Study of Sonlicromanol for Reducing Fatigue in Patients with Long COVID

What is this study about?

Who Can Join the Study?

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