Final answer:
A prescription becomes invalid in New Jersey when it has expired or in certain circumstances such as obtaining maximum refills or changes in insurance coverage.
Step-by-step explanation:
A prescription becomes invalid in New Jersey when it has expired. The expiration date is usually specified on the prescription label and typically ranges from one to twelve months from the date it was written by the doctor. Once the expiration date has passed, the prescription is no longer considered valid and cannot be filled by a pharmacist.
There are cases where a prescription may become invalid before the expiration date due to certain circumstances. For example, if a prescription is used to obtain the maximum allowed refills or if the patient's insurance coverage for the medication changes, the prescription may become invalid.