Final answer:
The FDA is responsible for issuing clinical trials and conducting postmarket surveillance programs for newly approved drugs.
Step-by-step explanation:
The organization responsible for issuing clinical trials and conducting postmarket surveillance programs for newly approved drugs is the Food and Drug Administration (FDA) in the United States.
The FDA requires pharmaceutical companies to conduct additional clinical trials, called Phase IV trials, as a condition of drug approval. These trials help gather more information about the drug's safety and effectiveness, especially in larger patient populations.
The FDA also monitors drugs after they are approved and on the market through postmarket surveillance programs to identify any potential safety concerns that may arise.