A nurse is preparing to administer digoxin 30 mcg/kg/day PO divided in equal doses every 8 hr to a school-age child who weighs 38 lb. Available is digoxin elixir 0.05 mg/mL. How many mL should the nurse administer per dose? (Round the answer to the nearest whole number. Use a leading zero if it applies. Do not use a trailing zero.)
Explanation & Rationale
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 38 pounds, which is approximately 17.27 kilograms (38 / 2.2 = 17.27). Next, calculate the total daily dose in micrograms by multiplying the child's weight in kilograms by the prescribed dose (17.27 kg * 30 mcg/kg/day = 518.1 mcg/day). Since the dose is divided into three equal parts to be given every 8 hours, divide the total daily dose by 3 (518.1 mcg/day / 3 = 172.7 mcg/dose). Now, convert the dose from micrograms to milligrams (172.7 mcg/dose * 0.001 = 0.1727 mg/dose). Finally, to find out how many milliliters of digoxin elixir to administer per dose, divide the dose in milligrams by the concentration of the elixir (0.1727 mg/dose / 0.05 mg/mL = 3.454 mL/dose). Rounding to the nearest whole number, the nurse should administer 3 mL per dose.