Not recruiting

Relative Bioavailability of Sisunatovir Capsules vs Tablets in Fasted and Fed Conditions in Healthy Adults with Respiratory Syncytial Virus

InvestigationalNo placebo

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What is this trial about?

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

The study examines a common virus that causes cold‑like symptoms, especially in young children and older adults, called Respiratory Syncytial Virus. The medication being tested is named Sisunatovir and is taken by mouth as a 200 mg capsule or tablet. The aim is to find out how well each form of the drug reaches the bloodstream.

The purpose of the study is to compare the bioavailability of the two formulations when taken on an empty stomach (fasted) and after eating either a low‑fat or a high‑fat meal. Healthy adult volunteers will receive a single dose of one form, then after a short break will receive the other form under the same conditions. During the trial participants will have simple checks such as blood samples, basic heart monitoring, and safety observations.

The research process

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

Step 1
Enrollment and baseline assessments
After giving informed consent you will be assigned a study identification number and will attend an initial visit.
During this visit basic health measurements, a brief medical history, and routine laboratory tests will be performed to confirm eligibility for the study.
Step 2
First single dose under fasted condition
You will arrive at the clinic after an overnight fast of at least eight hours; no food or drink except water is allowed.
A single oral dose of 200 mg sisunatovir will be given in the form of a capsule or a tablet, depending on the random assignment.
Blood samples will be taken at several time points over the next several hours to measure how much of the medicine reaches your bloodstream.
Step 3
Washout period
A break of several days will follow the first dose to allow the drug to be completely cleared from your body before the next administration.
No study medication will be taken during this time.
Step 4
Second single dose under fasted condition with alternate formulation
You will again fast for at least eight hours before arriving at the clinic.
The opposite formulation from the first period (tablet if you first received a capsule, or capsule if you first received a tablet) will be taken as a single oral dose of 200 mg sisunatovir.
Blood samples will be collected in the same manner as after the first dose to compare the two formulations.
Step 5
Single dose after a low‑fat meal (fed condition)
On a separate study day you will eat a standardized low‑fat meal provided by the clinic.
Shortly after finishing the meal you will take a single oral dose of 200 mg sisunatovir (capsule or tablet as assigned).
Blood will be drawn at multiple intervals to see how the low‑fat meal influences the amount of medicine that enters the blood.
Step 6
Single dose after a high‑fat meal (fed condition)
On another separate day you will eat a standardized high‑fat meal.
The same 200 mg oral dose of sisunatovir will be taken after the meal.
Blood sampling will be repeated to evaluate the effect of a high‑fat meal on drug absorption.
Step 7
Safety monitoring and study completion
Throughout each visit vital signs, a 12‑lead electrocardiogram (ecg), and routine laboratory tests will be performed to monitor safety.
Any side effects or adverse events you experience will be recorded.
After the final dosing period and safety assessments, the study will be concluded for you.

Who can join the trial?

3 criteria

Be a male or female who is at least 18 years old (or meets the legal age for consent in your country).
Be generally healthy, meaning you do not have serious medical problems, as judged by doctors through a review of your medical history (your past health records), a physical examination (a check‑up of your body), laboratory tests (blood and urine tests), and a cardiac evaluation (assessment of your heart).
Agree to take part as a healthy volunteer in the study.

Who cannot join the trial?

8 criteria

History or evidence of serious blood, kidney, hormone, lung, stomach, heart, liver, mental health, nerve, or allergy problems (including drug allergies), except mild seasonal allergies that are not being treated at the time of dosing.
Any current medical or mental health condition, including recent (within the past year) thoughts of suicide or abnormal lab results, that could raise the risk of taking part in the study or that the doctor thinks makes participation unsuitable.
Use of any prescription or over‑the‑counter medicines, dietary supplements, or herbal products within 7 days (or five drug half‑lives, whichever is longer) before the first dose, except certain strong enzyme‑affecting drugs (moderate/strong CYP3A inducers or time‑dependent inhibitors) which must be stopped at least 14 days (plus five half‑lives) before the first dose.
Having received any experimental drug or vaccine within the past 30 days (or longer if required locally) or within five half‑lives of that product before the first dose.
A positive urine drug test (confirmed by a repeat test) if the study team decides it is needed.
Blood pressure that is too high when measured lying down: for people under 60 years, systolic (top number) ≥140 mm Hg or diastolic (bottom number) ≥90 mm Hg; for people 60 years or older, systolic ≥150 mm Hg or diastolic ≥90 mm Hg. If high, the measurement must be repeated two more times and the average used.
An abnormal standard 12‑lead ECG (heart rhythm test) showing any of the following safety concerns: corrected QT interval (QTcF) >450 ms, complete left bundle branch block, evidence of a recent or unclear‑age heart attack, ST‑T changes suggesting reduced blood flow to the heart, second‑ or third‑degree atrioventricular block, serious slow or fast heart rhythms, or a QRS width >120 ms. If any of these are found, the ECG must be repeated twice and the average used.
Unacceptable lab test results at screening, confirmed by a repeat test if needed: estimated kidney function (eGFR) <60 mL/min/1.73 m², liver enzymes (AST or ALT) ≥1.05 times the normal upper limit, GGT >1.05 times normal, ALP >1.05 times normal, total bilirubin ≥1.05 times normal (unless the person has Gilbert’s syndrome and direct bilirubin is within normal limits).

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Investigated drugs

Sisunatovir
is an experimental oral medication being studied to see how well it is absorbed into the bloodstream. In this trial participants take a single dose of the drug in a hard capsule form. Researchers compare how much of the medicine reaches the blood when taken on an empty stomach versus after a meal.
Sisunatovir
is also being tested in a tablet form. The purpose is the same—to understand how the body absorbs the medicine—but the tablet shape may dissolve differently. By comparing the capsule and tablet, scientists can decide which form works best under fed and fasted conditions.

Sisunatovir

What is already known about the treatment

Sisunatovir - This medication is taken by mouth as a 200 mg hard capsule or tablet, swallowed with water. It is still experimental and currently being studied in a Phase 1 trial, so it is not yet approved for regular medical use. The drug is being investigated to treat infections caused by respiratory syncytial virus (RSV). It works by blocking a key viral enzyme needed for the virus to copy its genetic material, and it belongs to the class of antiviral medicines that target RSV.

Investigated diseases

Respiratory syncytial virus (RSV) - Respiratory syncytial virus (RSV) is a common viral infection that primarily affects the airways of infants, young children, and older adults. The virus spreads through droplets and can cause symptoms such as runny nose, cough, and fever. In the lower respiratory tract it can lead to inflammation of the bronchioles, producing wheezing and difficulty breathing. The illness usually peaks within a few days and then gradually improves, although some people may experience a prolonged cough. Re‑infection can occur because immunity does not last long.