Which of the following is the correct meaning for "prn"?

The term "prn" is derived from the Latin phrase "pro re nata," which translates to "as needed." In medical terminology, this is commonly used to indicate that a medication or treatment should be administered only when required rather than on a fixed schedule. For instance, a patient may be prescribed pain medication to take "prn," meaning they should take it only when they are experiencing pain, rather than at specific time intervals. This allows for flexibility in treatment based on the patient's immediate needs and conditions, making option C the accurate interpretation of "prn."

The other options suggest meanings that do not align with standard medical terminology. For example, "Per Required Necessity" implies a more specific guideline that could confuse the idea of administering treatments based solely on the patient's needs. "Prior Risk Notification" refers to an entirely different concept concerning potential warnings before a procedure or treatment, and "Permanent Record Notation" suggests a documentation practice unrelated to the timing of medical interventions. These alternative interpretations do not capture the primary intent of "prn" in clinical settings.