Early and late phase clinical trials involving new drugs classified into four phases, having knowledge of each phase is essential in understanding what is currently known about an investigational therapy. There are advantages and disadvantages associated with treatment in each specific phase. Information gathered in each phase determines whether the study can move on to the next phase and whether the drug or treatment is approved for use.
Phase 1: The first step is testing a particular medical treatment in humans, to fulfil the goal of gathering the information on timings, safety and dosages of the new drug.
Phase 2: Designed to study the safety and effectiveness of an investigational therapy.
Phase 3: Designed to evaluate the effectiveness of the new treatment compared to standard treatment.
Phase 4: Designed to further track side effects and benefits on a long-term basis after a drug has been FDA-approved.