Final answer:
Internet pharmacies must notify the FDA of unexpected serious and fatal adverse drug events within 15 days post NDA approval, and other events on a quarterly basis, in compliance with the Prescription Drug Marketing regulations.
Step-by-step explanation:
The question pertains to the regulatory obligations of internet pharmacies concerning the notification of changes in Prescription Drug Marketing (PDM). After New Drug Application (NDA) approval, the sponsor is required to monitor and report any patient adverse drug experience to the Food and Drug Administration (FDA). This includes reporting unexpected serious and fatal adverse drug events within 15 days, and other events on a quarterly basis. Moreover, the FDA receives adverse drug event reports through its MedWatch program, which relies on voluntary reporting by consumers and health professionals, often referred to as "spontaneous reports".