A nurse is preparing to administer digoxin 12 mcg/kg/day PO to divide equally every 12 hr to a school-age child who weighs 66 lb. Available is digoxin elixir 0.05 mg/mL. How many mL should the nurse administer per dose? (Round the answer to the nearest tenth. Use a leading zero if it applies. Do not use a trailing zero.)

To calculate the dosage of digoxin for the child, first convert the child's weight from pounds to kilograms, knowing that 1 kilogram equals 2.2 pounds. The child weighs 66 pounds, which is approximately 30 kilograms (66 ÷ 2.2). The prescribed dose is 12 micrograms per kilogram per day, which equals 360 micrograms per day (12 mcg × 30 kg). Since the dose is divided every 12 hours, the child should receive 180 micrograms every 12 hours. The digoxin elixir is available at a concentration of 0.05 mg/mL, which is the same as 50 micrograms per milliliter. To find out how many milliliters to administer per dose, divide the dose in micrograms by the concentration: 180 mcg ÷ 50 mcg/mL equals 3.6 mL.