Final answer:
After the New Drug Application (NDA) has been submitted and approved, drug manufacturers must conduct Phase IV clinical trials and engage in continuous pharmacovigilance by monitoring and reporting adverse drug experiences to ensure ongoing safety and efficacy.
Step-by-step explanation:
All drug manufacturers are required to conduct specific types of studies after the New Drug Application (NDA) has been submitted and approved. These additional studies are primarily Phase IV clinical trials, which monitor the safety, efficacy, and optimal use of a drug once it is marketed. As part of the post-approval requirements, the drug sponsors must continue to evaluate the drug through a pharmacovigilance system, keeping track of all adverse drug experiences and reporting serious and unexpected events within 15 days to the FDA. The FDA also receives reports of adverse drug events through its MedWatch program. These requirements ensure the drug remains safe for public consumption and permits the identification of any long-term effects or effects on specific subgroups of patients that were not apparent during the pre-approval clinical trials.