Which of the following could indicate a potential forgery of a controlled substance prescription?

An unusually large quantity of a controlled substance on a prescription can indeed indicate a potential forgery. This is because legitimate prescriptions typically follow prescribed guidelines for dosing and quantity, which are intended to ensure the safety and effectiveness of treatment. When a prescription requests a significantly larger quantity than what would be considered appropriate for the condition being treated or exceeds recommendations for safe use, it raises red flags for healthcare professionals.

In contrast, other factors such as a patient having a known medical history or the signature of a licensed pharmacist do not inherently suggest forgery. A known medical history may support the legitimacy of the medication request, and a pharmacist’s signature implies that the prescription comes from a registered provider, which typically confirms its validity rather than raises suspicion. Additionally, while multiple refills can sometimes be a cause for concern, they are permissible under certain circumstances and do not automatically signify a problem without additional context. Thus, the presence of an unusually large quantity is a strong indicator that further investigation is warranted.