Types of Clinical Trials

Types of trials:

Phase I:

First time a new drug or regimen is tested on humans
Few participants (say <30)
Primary aims are to find a dose with an acceptable level of safety, and examine the biological and  pharmacological effects

Phase II :

Not too large (say 30–70 people)
Aim is to obtain a preliminary estimate of efficacy
Not designed to determine whether a new treatment works
Produces data in each of the trial arms, that could be used to design a phase III trial

Phase III:

Must be randomised and with a comparison (control) group
Relatively large (usually several hundred or thousand people)
Aim is to provide a definitive answer on whether a new treatment is better than the control group, or is similarly effective but there are other advantages

Phase IV:

Relatively large (usually several hundred or thousand people)
Used to continue to monitor efficacy and safety in the population once the new treatment has been adopted into routine practice.