A patient with a respiratory infection asks the nurse why some antibiotics are prescribed to be taken every 12 hours and some have to be taken 4 times a day. What is the nurse's best response?

Question

a. "The time between doses changes because any medication's half-life varies so much."
b. "We need to vary the times to keep the blood values fluctuating."
c. "We try to give the next dose of medication only after the last dose is gone."
d. "Regular doses are given based on the half-life to maintain a therapeutic plateau."

Answer 1

D
All medications have a biologic half-life, which is the time it takes for the body to lower the amount of unchanged medication by half. A drug with a short half-life (e.g., 2 to 3 hours) needs to be given more frequently than a drug with a longer half-life (e.g., 10 to 12 hours). A medication's half-life does not change with the dose of the medication; its half-life is always the same no matter how much medication is administered. To maintain a therapeutic plateau, a patient receives regular fixed doses at specific intervals that correspond with their half-life. The goal of medication administration is to achieve a therapeutic plateau, a point at which the blood level of a medication remains consistent. After an initial medication dose, the patient receives each successive dose when the previous dose reaches its half-life.