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Clinical trial phases

A clinical trial consists of four phases :

  1. Phase I
    The new drug is tested for the first time in humans on a small group of subjects to evaluate its safety.
  2. Phase II
    The new drug is tested on a small group of patients who are suffering from the disease targeted by the new drug. Phase II aims at evaluating the efficacy of the new investigational product and its side effects.
  3. Phase III
    The new drug is tested on a large group of patients, for a longer period of time than phase II trials, to confirm its efficacy and investigate its side effects long term. If the new drug turns out to be safe and effective in Phase III, the health authorities might approve it for marketing to make it available to the general population.
  4. Phase VI
    Once the new drug is marketed and widely used, monitoring the new drug’s efficacy and safety continues in phase VI.