Randomized, crossover, comparative bioavailability study of two tadalafil formulations (oral suspension and film-coated tablets) after a single oral dose of 20 mg under fed conditions in healthy male volunteers.
This early-stage study looks at tadalafil, a medicine widely used for erectile problems and prostate symptoms. Currently, it is usually taken as a solid tablet. Scientists have developed a liquid version to help people who have difficulty swallowing pills. Researchers want to see if the body absorbs the liquid version in the exact same way as the standard tablet when taken after food. Healthy male volunteers will take a single 20 mg dose of each form on two separate occasions, with a break in between. Blood samples will be taken over several hours to measure drug levels in the bloodstream. Because this is a trial in healthy volunteers, there is no direct health benefit to taking part. However, it helps ensure the liquid medicine is reliable and safe. Participation is completely voluntary, and volunteers can leave the study at any time.
At a glance
What is this study about?
Tadalafil is a well-known medicine that relaxes blood vessels to improve blood flow. Doctors frequently prescribe it to treat erectile dysfunction and urinary symptoms caused by an enlarged prostate gland. At present, most people take tadalafil as a film-coated tablet that must be swallowed whole. However, many people find swallowing tablets difficult or uncomfortable. To solve this, researchers have formulated a liquid version (an oral suspension) that can be drunk instead.
Before a new medicine form can be approved for general use, scientists must prove that it works in the body just as well as the original version. This type of research is called a comparative bioavailability study. It measures how quickly the medicine gets into the bloodstream and how much of it is absorbed. In this study, volunteers will take the medicine after eating a meal, because food can sometimes change how quickly a drug enters the body.
This is a Phase 1 clinical trial, which means it tests the medicine in healthy volunteers first rather than people with medical conditions. By taking part, volunteers help gather the essential safety and absorption data needed before this liquid option can potentially be made available to patients across the UK.
Key takeaways
- Tests a new easy-to-swallow liquid form of tadalafil against the regular tablet.
- Open to healthy adult men aged 18 and older.
- Each volunteer tries both the liquid and tablet after eating a meal.
- Requires blood samples to measure how much medicine enters the bloodstream.
- Taking part is completely voluntary, with health checks provided throughout.
Who may be eligible?
This trial is looking for healthy men aged 18 and over. Because the purpose of the study is purely to measure how the human body processes the medicine, participants must be in good general health without any major medical conditions.
You are unlikely to be able to take part if you take regular prescription medicines, have heart conditions, or suffer from blood pressure problems. You will also need to be comfortable eating a standard study meal and giving regular blood samples across the clinic visits.
Before you can join, the study team will carry out a thorough health check. This will typically include blood tests, a heart check (ECG), and a physical examination to confirm that it is entirely safe for you to take part.
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 am in good general health with no major illnesses.
- I do not take regular prescription medicines.
- I have no history of heart or blood pressure problems.
- I am comfortable eating a provided meal and having blood samples taken.
What does participation involve?
Taking part involves attending a specialist clinical research unit. During the trial, you will test both the liquid and tablet forms on two separate visits. On each study day, you will eat a set meal and then take a single 20 mg dose of tadalafil. A nurse or doctor will take small blood samples from your arm at set times over several hours to measure the levels of medicine in your body. Because this is a crossover study, you will have a break of at least one to two weeks between the two doses so the first dose completely clears from your system. In total, taking part involves an initial screening visit, two dosing visits (which may involve spending the day or an overnight stay at the unit), and a final follow-up health check.
Potential risks and benefits
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Common questions
Why is the study only for men?
Tadalafil is mainly used to treat male health conditions, and early Phase 1 absorption studies are often kept to a single sex to keep the data as consistent and clear as possible.
What does a 'crossover' study mean?
It means every volunteer tests both formulations. You will take the tablet on one visit and the liquid on another, allowing researchers to compare both forms in the exact same person.
Why do I have to take the medicine after eating?
Food can change how quickly a medicine is absorbed into your blood. Testing both forms under 'fed conditions' shows whether a meal affects the liquid version in the same way as the tablet.
Will taking tadalafil cause a permanent erection?
No. Tadalafil only works when someone is sexually aroused. Prolonged, painful erections are an extremely rare side effect, and medical staff will be on hand throughout the study.
Can I leave the study early if I feel uncomfortable?
Yes. You can leave the trial at any point, for any reason, without any penalty or impact on your normal medical care.
How to find out more
Always speak to your GP or specialist before deciding to take part in a study.
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