Phase 0
Pharmacodynamics & pharmacokinetics in humans
Phase 0 trials are the first-in-human trials. Single subtherapeutic doses of the study drug or treatment are given to a small number of subjects (10 to 15) to gather preliminary data on the agent’s pharmacodynamics (what the drug does to the body) and pharmacokinetics (what the body does to the drugs).[32] For a test drug, the trial documents the absorption, distribution, metabolization, and removal (excretion) of the drug, and the drug’s interactions within the body, to confirm that these appear to be as expected.
Phase 1
Clinical trials, researchers test a new drug or treatment for the first time in a small group of normal, healthy volunteers (about 20 to 80) to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2
Clinical trials, the study drug or treatment is given to a larger group of people (about 100 to 300), including patients with the particular disease, to see if the drug or treatment is effective, and to further evaluate its safety.
Phase 3
Clinical trials, the study drug or treatment is given to large groups of people (from 1,000 to 3,000), including patients, to confirm its effectiveness, monitor side effects, compare it to other commonly used treatments, and to collect information that will allow the drug or treatment to be used safely.
Phase 4
Clinical trials are done after the drug or treatment has been approved by the DCGI and marketed for public use. These studies continue testing the drug or treatment to collect information about its effect in various populations and gather data on any side effects associated with long-term use.