Pilot, randomized, crossover, comparative bioavailability study of two tadalafil formulations (oral suspension and film-coated tablets) after a single oral dose of 20 mg under fasting conditions in healthy male volunteers.
This clinical research study compares two different forms of a medicine called tadalafil. Tadalafil is widely used to treat erectile dysfunction and certain blood pressure conditions. Currently, it is usually swallowed as a solid tablet. Researchers have developed a liquid version, which may be much easier to take for people who struggle to swallow pills. In this trial, healthy adult men will test both the liquid and the regular tablet, taken at separate times on an empty stomach. Researchers will take regular blood samples to measure how quickly and completely each form enters the bloodstream. The main goal is to confirm whether the new liquid form works in the body just like the approved tablet. The findings will help doctors know if the liquid is a reliable alternative for patients in the future.
At a glance
What is this study about?
Tadalafil is a well-known medicine commonly prescribed for erectile dysfunction and certain circulatory conditions. While most people take it as a film-coated tablet, swallowing pills can be difficult for some individuals, such as older adults or people with throat conditions. To help solve this problem, scientists have created an oral liquid suspension of tadalafil that can be swallowed easily.
Before a new form of a medicine can be prescribed by doctors, researchers must prove that the body absorbs it properly. This study measures what is known as 'bioavailability'—the rate and amount of medicine that enters the bloodstream after taking it. By comparing the liquid directly against the standard tablet, researchers can confirm whether both forms behave the same way in the human body.
This trial is a 'crossover' study, meaning each participant will try both the tablet and the liquid at different times. Testing both products in the same person allows scientists to make a fair and direct comparison. Because this is an early safety and absorption study, it is carried out in healthy volunteers first to gather clear, accurate data before the liquid is tested in wider patient groups.
Key takeaways
- Compares a new liquid tadalafil with the standard swallowed tablet.
- Open to healthy male volunteers aged 18 and over.
- Checks if the body absorbs both forms in the same way.
- Involves taking single doses on an empty stomach and giving blood samples.
- Could provide an easier option for people who struggle to swallow pills.
Who may be eligible?
This study is open to healthy adult men aged 18 and older. Because the goal is to study how the medicine behaves naturally in the body, participants must be in good general health without any major ongoing illnesses.
To be eligible, you must be comfortable fasting (not eating) before taking the medicine and willing to provide blood samples throughout the study days. You will undergo health checks, such as blood tests and heart tracings, to ensure taking part is safe for you.
You cannot take part if you have significant heart, liver, or kidney problems, or if you take certain medicines like nitrates (often prescribed for chest pain), as combining them with tadalafil can cause an unsafe drop in blood pressure.
Could this study suit you?
Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.
- I am a man aged 18 or older.
- I consider myself to be in good general health.
- I do not have heart, liver, or kidney disease.
- I do not take nitrate medicines for chest pain.
- I am willing to fast overnight and attend clinic visits for blood tests.
What does participation involve?
Taking part involves an initial screening visit followed by two separate clinic stays or day visits. During the first visit, you will fast overnight and take a single 20 mg dose of either the tablet or the liquid medicine. Clinical staff will take small blood samples at set times throughout the day to measure medicine levels. You will then have a 'washout' period of one to two weeks with no medicine, allowing your body to clear it completely. After this break, you will return to the clinic to repeat the process with the other form of the medicine. A short follow-up check will ensure you are feeling well. In total, participation usually lasts a few weeks.
Potential risks and benefits
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Common questions
Why are only healthy men invited to join?
Testing new medicine forms in healthy volunteers first helps scientists see how the drug is absorbed without interference from other illnesses or daily medications.
What does a 'crossover' study mean?
It means you will test both the liquid and the tablet on separate days, so your own results can be directly compared.
Why do I need to fast before taking the medicine?
Food can change how quickly a medicine enters the blood. Fasting ensures that both forms are tested under the exact same conditions.
Will I be compensated for my time?
Early-stage studies with healthy volunteers often provide payment to cover your travel and time. The study team can give you full details.
What happens if I decide I want to stop?
You are free to withdraw from the trial at any point. Your decision will not affect your standard medical care in any way.
How to find out more
Always speak to your GP or specialist before deciding to take part in a study.
Interested in taking part?
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