What is a clinical trial?
Once a candidate drug has been tested and characterized in animals, it is ready to be tested in humans and enters the clinical phase of development. Initial clinical studies are usually performed in healthy male volunteers, testing single, followed by multiple, doses of the drug. A proof-of-concept study is conducted to provide the first evidence that a candidate drug might be effective for a disease. At all stages of clinical development, the criteria for continuing to investigate the candidate drug include safety, tolerability, pharmacokinetics, duration of action, efficacy, patient acceptability, and commercial viability at the planned time of launch.
The different phases of clinical trials/studies are described in the table below. Phase 1, 2 and 3 clinical trials are conducted prior to marketing of the drug, while Phase 4 trials are conducted after the drug has received marketing approval.
Clinical trial phases
| Phase | Population type | Scale Duration | Main objective |
| Phase I | Healthy volunteers or patients (if cancer or AIDS is being studied) | Very small Days | Safety Tolerability Pharmacodynamics Pharmacokinetics |
| Phase II | Patients (hospitals) | Small Weeks | Safety Tolerability Proof-of-concept Dose-ranging/finding Preliminary efficacy |
| Phase III | Patients (hospital or general practice) | Large Months | Long-term safety and efficacy vs competition drugs |
| Phase IV | Patients (general practice) | Very large Months/years | Long-term safety, tolerability and efficacy in real life patients |
Participation in Actelion trials
To find out more about ongoing Actelion studies, please visit the Actelion clinical trial database called Smadar.
If you are interested in participating in an Actelion clinical trial, please contact your physician.
