Phases of clinical trials

Phase of a clinical trial – stage of a trial studying a drug or biological product. The phase is determined by the study's objective, the number of participants, and other characteristics.

Overview of clinical trial phases

• Phase I: This phase usually tests new drugs for the first time in a small group of people who have no underlying health conditions. The aim is to evaluate a safe dosage range and identify side effects. Investigators also look at the best way to administer the drug, such as orally, intravenously, or topically.
• Phase II: This phase involves several hundred participants who are living with the condition that the new medication is meant to treat. They are usually given the same dose that was found to be safe in the previous phase. Investigators monitor participants for several months or years to see how effective the medication is and to gather more information about any side effects it might cause.
• Phase III: This phase is conducted on larger populations and in different regions and countries and is often the step right before a new treatment is approved. The aim is to confirm the effectiveness of the new intervention, monitor side effects, compare it to commonly used treatments, and collect information that will allow the intervention to be used safely.
• Phase IV: These are post-marketing studies which takes place after country approval that delineate additional information, including the treatment's risks, benefits, and optimal use.

Each phase is crucial in the development of a new drug or treatment and provides important information about its safety and effectiveness.

The phase concept is a description and not a requirement, and the phases of drug development may overlap or be combined (ICH E8 4.3 ).

External links

• US FDA web site, "Step 3: Clinical Research", 04 Jan 2018, https://www.fda.gov/patients/drug-development-process/step-3-clinical-research