PRN: As needed.

PRN: As needed.

• A. Onset of action
• B. PRN
• C. Half-life of a drug
• D. Elimination

Answer: (B)

PRN means taking the medication as needed, rather than on a fixed schedule. This instruction focuses on when to dose—use it to treat symptoms as they arise—not on how quickly the drug acts, how long it stays active, or how it’s removed from the body. In this context, onset of action refers to the time from dosing to the beginning of effect, half-life is about how long it takes for the drug concentration to drop by half, and elimination describes the process of removing the drug from the body. Since the item is asking about when to take the drug, PRN is the best fit.

PRN means taking the medication as needed, rather than on a fixed schedule. This instruction focuses on when to dose—use it to treat symptoms as they arise—not on how quickly the drug acts, how long it stays active, or how it’s removed from the body. In this context, onset of action refers to the time from dosing to the beginning of effect, half-life is about how long it takes for the drug concentration to drop by half, and elimination describes the process of removing the drug from the body. Since the item is asking about when to take the drug, PRN is the best fit.