How many phases of clinical trials are required for new drug approval?
Usually, three phases of clinical trials are required for new drug approval. They will be Phase I, Phase II, and Phase III. Phase I trials are the first stage of testing in human subjects. Normally, a small (20 – 50) group of healthy volunteers will be selected. It is designed to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of a drug. Phase II trials are performed on larger groups (20 – 300) to assess how well the drug works, as well as to continue Phase I safety assessments in a larger group of patients. During Phase II trials, drug candidate may be discovered not to work as planned, or to have toxic effects. Phase III studies are randomized controlled multicenter trials on large patient groups (300 – 3,000 or more) and are aimed at being the definitive assessment of how effective the drug is. Because of their size and long duration, Phase III trials are the most expensive, time-consuming and difficult trials to design and run. Sometimes, Phase IV studies ar
