Clinical trials are usually described based on their phase. There are four phases. Below you find the explanation per phase.
What is phase 1 of a clinical trial?
Phase 1 of clinical trial consists of a first administration in subjects, usually conducted with a small group of healthy volunteers. Tolerance and safety are observed, generally by increasing the dosage. It also often concerns an evaluation of metabolisation and excretion.
What is phase 2 of a clinical trial?
Phase 2 of clinical trial consists of a first administration in a small group of subjects with a certain disease or condition. Verification of the active mechanism in patients and safety when used for a short period of time including monitoring of all potential side effects. Phase 2a are the proof of concept studies and Phase 2b are the definite dose-finding studies.
What is phase 3 of a clinical trial?
This phase primairly consists of testing the final dosage in real world medical practice on its usability and effectiveness in a larger group of subjects. Safety in the short and longer terms are observed.
What is phase 4 of a clinical trial?
The final phase of a clinical trial. Research after authorisation and related to the indication area for which the product is authorised. The trials performed are not necessary for authorisation purposes, though gather additional information about safety, efficacy and optimal use.