A nurse is preparing to administer diphenhydramine 1.25 mg/kg IM to a child who weighs 68 lb. Available is diphenhydramine injection 50 mg/mL. How many mL should the nurse administer? (Round the answer to the nearest tenth. Use a leading zero if it applies. Do not use a trailing zero.)

Convert the child's weight from pounds (lb) to kilograms (kg). Child's weight (kg) = 68 lb / 2.2 lb/kg = 30.9 kg. Calculate the total dose in milligrams (mg). Total dose (mg) = Child's weight (kg) x Ordered dose (mg/kg) = 30.9 kg x 1.25 mg/kg = 38.625 mg. Calculate the volume to administer in milliliters (mL). Volume (mL) = Total dose (mg) / Available concentration (mg/mL) = 38.625 mg / 50 mg/mL = 0.7725 mL. Round to the nearest tenth = 0.8 mL.