Phase IV clinical trials refer to studies conducted after the product has been approved.

Phase IV studies are done to:

• Gain additional information about the drug’s risks, benefits and optimal use
• Evaluate different doses or schedules of administration than were evaluated in the previous phases
• Evaluate the use of the drug over longer periods of time

 NOTE: If a new indication or new disease is identified for which the drug may be used, the sponsor must conduct clinical studies and resubmit an NDA for the specific indication, prior to marketing the drug for that indication.

Historically, Phase IV studies also focused on pharmacoeconomic (cost effectiveness) and quality of life data, although there is a trend towards including these aspects into Phase II and III trials.