Final answer:
Doctors must monitor for adverse reactions and treatment response when starting Vraylar to assess long-term safety and effects in various patient subgroups, as part of a pharmacovigilance system.
Step-by-step explanation:
Doctors should monitor patients for adverse reactions and treatment response when starting a medication like Vraylar because, even after a drug is approved, it is subject to a rigorous pharmacovigilance system. Ongoing monitoring is crucial because it helps in evaluating the long-term safety and the drug's effect in different patient subgroups that were not necessarily part of the initial clinical trials. For instance, evaluating the pharmacokinetics and tolerability of extended-release tablets like gabapentin enacarbil after oral administration is an essential process to ensure medication safety and efficacy.