Phases of Clinical Trials
Quick overview of the different phases of clinical trials
Also known as ‘First-in-Humans’, they are the first stage for medical devices or drug testing in human subjects. Their primary purpose is to assess safety, and for drug trials specifically, the pharmacokinetics, pharmacodynamics, and tolerability. These non-randomized trials usually include a relatively small number of healthy subjects (typically 20 to 100) and can last up to one year.
The goal of this second phase of trials is to determine if a medical device or a drug has any effect or biological/therapeutic activity while continuing to perform Phase I safety assessments. These Phase II trials are generally randomized and conducted with a larger group of subjects who are affected by the medical condition intended to be treated (50-300). These trials can last up to two years.
At this point, the drug is presumed to have some effect and this clinical trial phase helps determine the effectiveness of the new medical device or drug. These Phase III trials are typically randomized and conducted simultaneously in different hospitals/clinics. They involve large groups of subjects with the medical condition of interest (300-3000) and can last up to 5 years.
Also known as ‘Postmarketing Surveillance’, they are part of a continuous safety surveillance process called Pharmacovigilance. The goal of the Phase IV trial is to monitor long-term or rare adverse effects of medical devices or drugs once they have been released for general sale. As a result, this type of trial takes place with a very large subject population (thousands and up) and over a longer period of time compared to Phase I, II and III trials. At this stage, anyone seeking treatment from a physician can receive the medical device or the drug.