A nurse is planning to administer diphenhydramine 1.25 mg/kg IV to a school-age child who weighs 55 lb. Available is diphenhydramine 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 weight from pounds to kilograms: 55 lb / 2.2 lb/kg = 25 kg Calculate the total milligrams of diphenhydramine needed: Dose (mg/kg) x Weight (kg) = Total milligrams 1.25 mg/kg x 25 kg = 31.25 mg (round to 31.3 mg) Determine the volume of diphenhydramine solution needed: Total milligrams / Concentration (mg/mL) = Volume (mL) 31.3 mg / 50 mg/mL = 0.63 mL (round to nearest tenth) Therefore, the nurse should administer 0.6 mL of diphenhydramine 50 mg/mL