Final answer:
A prospective drug review (PDR) is required when a sponsor must conduct additional clinical trials, when risk management plans are required by the FDA, and when continuous evaluation of a drug's safety and effectiveness is necessary.
Step-by-step explanation:
A prospective drug review (PDR) is required in several instances:
- As a condition of approval, a sponsor may be required to conduct additional clinical trials, called Phase IV trials.
- The FDA may require risk management plans for certain drugs, which may involve additional studies, restrictions, or safety surveillance activities.
- Even after approval, a drug must continue to be evaluated through a pharmacovigilance system to monitor long-term safety and effectiveness.