Testing of a new drug or treatment in people.

Early stages of drug discovery and development involve in vitro studies and work on animal models. After this preclinical phase, promising drugs enter clinical development, which typically involves three distinct phases of clinical trials:

  • Phase 1: first use in human volunteers, to assess safety and pharmacokinetics
  • Phase 2: first testing in patients, to check safety, provisional efficacy, and to test different doses
  • Phase 3: efficacy testing in a larger number of patients

See also phase 1, 2, 3, 4 trials.