Final answer:
An over-the-counter (OTC) product dispensed as a prescription has a beyond use date determined by the pharmacist, which accounts for the medication's safety, effectiveness, and storage conditions, and is generally more conservative than the manufacturer's expiration date.
Step-by-step explanation:
When an over-the-counter (OTC) product is prescribed and dispensed as a prescription, the beyond use date (also known as the expiration date) is generally determined by the pharmacist, based on various guidelines. The beyond use date is not simply the date until which the medication is effective, but it also indicates the timeframe in which the medication is expected to remain safe to use and retain its intended efficacy. It accounts for factors such as the properties of the medication, the type of container it's dispensed in, the environment in which it will be stored, and the manner in which it will be used.
For instance, some OTC medications may have a manufacturer's expiration date that extends two to three years from the date of manufacture. However, once they are repackaged or mixed by the pharmacy (for instance, when making a compounded medication), the pharmacist must assign a beyond use date that is conservative to ensure safety and effectiveness. This period is typically shorter than the original manufacturer's expiration date and may follow specific state regulations or professional standards. For example, the United States Pharmacopeia (USP) provides guidelines on standard beyond use dates after repackaging.