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Safety, Tolerability and Pharmacokinetics of MK-4318 in Healthy Adults with Pain

Fast replyInvestigationalNo placebo
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What is this trial about?

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

The trial investigates a medication called MK-4318 for the relief of Pain. The main goal is to see if the drug is safe, well‑tolerated, and how it moves through the body after several oral doses. Healthy adult volunteers will receive either the study drug in capsule form or an inactive capsule that looks the same, known as a placebo.

Participants will take a capsule once daily for a short period while researchers collect blood samples at set times to measure the amount of drug in the bloodstream. This measurement process, called pharmacokinetics, helps determine how quickly the drug is absorbed, how high the concentration becomes, and how long it stays in the system. Throughout the study, volunteers are monitored for any side effects, and any health changes are recorded. The study ends after the dosing period and the final follow‑up assessments are completed.

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

    Initial screening and consent

    You will meet study staff who will explain the purpose of the trial and ask you to sign a consent form. this confirms that you understand the study and agree to take part.

    The staff will check your health status with a brief medical history, a physical check, and basic laboratory tests to make sure you meet the study requirements.

  2. Step 2

    Baseline assessments

    Before receiving any medication, you will undergo baseline measurements such as blood pressure, heart rate, and a blood sample. these results provide a reference point for later comparisons.

  3. Step 3

    Receiving study medication

    You will be given a supply of capsules. the active medication is mk-4318, an oral capsule containing 400 mg of the study drug. if you are assigned to the control group, you will receive a placebo capsule that contains only inactive ingredients such as microcrystalline cellulose, lactose monohydrate, and magnesium stearate.

    Each capsule is taken by mouth.

  4. Step 4

    Taking the medication

    You will take one capsule each day as instructed by the study protocol. the dose is 400 mg for the active medication; the placebo capsule has no active drug.

    The capsule is swallowed with water and should be taken at the same time each day to keep the schedule consistent.

  5. Step 5

    Scheduled safety visits and blood draws

    Throughout the dosing period you will return to the clinic on predetermined days. during each visit, staff will perform a safety assessment that includes checking vital signs and asking about any side effects.

    A small amount of blood will be collected (blood draw) to measure the level of mk-4318 in your plasma and to monitor other laboratory values.

  6. Step 6

    Continuing medication and monitoring

    You will continue to take the capsule daily and attend all scheduled visits until the dosing schedule outlined by the study is completed.

    Any adverse events or concerns you experience should be reported to the study staff during these visits.

  7. Step 7

    Final assessment and study completion

    At the end of the dosing period you will have a final visit that includes a complete safety check, a final blood draw, and a review of the overall study results.

    After this visit the study medication will be stopped and you will be considered to have completed the trial.

Who can join the trial?

4 criteria

  • Be in good health (no serious illnesses or medical problems).
  • Be any sex or gender and be between 18 and 55 years old, inclusive.
  • If assigned male at birth and able to produce sperm, agree to use birth control for at least 90 days, avoid vaginal intercourse, and follow the study’s contraception instructions.
  • If assigned female at birth, must be a participant of non‑childbearing potential (meaning you cannot become pregnant, such as after menopause or having had a procedure that prevents pregnancy).

Who cannot join the trial?

15 criteria

  • Has a history of serious problems with endocrine (hormone) systems, gastrointestinal (digestive) organs, cardiovascular (heart and blood vessels) health, hematological (blood) disorders, hepatic (liver) disease, immunological (immune system) issues, renal (kidney) problems, respiratory (breathing) conditions, genitourinary (urinary and reproductive) abnormalities, or major neurological (brain and nerve) diseases, including stroke and long‑term seizures.
  • Is unable to avoid using any medication, including prescription drugs, over‑the‑counter medicines, or herbal remedies.
  • Has taken part in another investigational study within the past 4 weeks (or within five drug half‑lives, whichever is longer; a half‑life is the time it takes for half of a drug to leave the body).
  • Is a smoker or has used nicotine or nicotine‑containing products (such as nicotine patches or electronic cigarettes) within 3 months before screening.
  • Consumes more than three alcoholic drinks per day.
  • Drinks large amounts of coffee, tea, cola, energy drinks, or other caffeinated beverages each day.
  • Regularly uses cannabis, any illegal drugs, or has a history of drug (including alcohol) abuse within roughly the past 2 years.
  • Is mentally or legally unable to make decisions, or has significant emotional problems.
  • Is at immediate risk of harming yourself.
  • Has a history of cancer (malignancy).
  • Has multiple or severe allergies.
  • Tests positive for hepatitis B surface antigen, hepatitis C antibodies, or human immunodeficiency virus (HIV).
  • Has had major surgery or donated or lost about 500 mL (one unit) of blood within the past 4 weeks.
  • Has a history of cardiac arrhythmia (irregular heartbeat) or recurrent unexplained syncope (fainting) events.
  • Has a first‑degree relative (parent, sibling, or child) with multiple unexplained fainting episodes, unexplained cardiac arrest, sudden cardiac death, or a known family history of an inherited arrhythmia syndrome (such as Brugada syndrome).
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Investigated drugs

MK-4318 is an experimental oral capsule being tested in healthy volunteers. In this study the participants take the capsule by mouth to see how well they can tolerate it and whether it is safe. Researchers also measure how the drug moves through the body, such as how quickly it is absorbed into the blood and how long it stays there. The goal is to gather information about the safety, side‑effects, and the way the body handles the medication before it can be tested for treating any disease.

What is already known about the treatment

MK-4318 - MK-4318 is taken as an oral capsule containing 400 mg of the drug and is swallowed with water. It is an investigational medicine that is still being studied in clinical trials and is not yet approved for regular medical use. The study is looking at its ability to relieve pain by influencing the way nerve cells send pain signals, acting as a nerve‑signal modulator. It is classified as an experimental analgesic agent.

Investigated diseases

Pain - Pain is an uncomfortable feeling that signals the nervous system that something may be wrong. It can be sharp, dull, or throbbing and may appear in any part of the body. Acute pain usually begins suddenly after an injury and fades as the tissue heals. If the cause persists, pain can become chronic, lasting weeks, months, or longer, and may spread to nearby areas. Ongoing pain can affect daily activities and may lead to increased sensitivity over time.
Trial detailsLast updated 4 Oct 2026
Age18+ yearsPhasePhase ITrial ID2023-507512-12-00Protocol codeMK-4318-002Estimated enrolment32 patientsSponsorMerck Sharp & Dohme LLC

sourced from the EU Clinical Trials Register and site verification

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On this site, “treatment” means an investigational medicine being studied in a clinical trial. Its safety and efficacy for the use being studied have not yet been confirmed, some participants may receive a placebo or a comparator medicine, and taking part does not guarantee any health benefit. The decision to take part is made by the doctor at the research site. This site is for information only and does not replace medical advice.

This service is not affiliated with the European Commission, the EMA, or the official CTIS system. Most information comes from publicly available international clinical-trial registries, supplemented by data from academic sites, national regulators and commercial sponsors. On this site, “treatment” and “therapy” mean a medicine being tested in a clinical trial. Its safety and effectiveness in the use being studied are not yet confirmed, some participants may receive a placebo or a comparator, and taking part does not guarantee a health benefit. The doctor at the research site decides who can take part. This site provides information, not medical advice. Certain content and visual elements on this website have been generated or enhanced using artificial intelligence (AI).