An infant who weighs 22 lb receives a prescription for amoxicillin 20 mg/kg/day PO in divided doses every 8 hours. The bottle is labeled, "Amoxicillin for Oral Suspension, USP 250 mg per 5 mL." How many mL should the nurse administer with each dose? (Enter numerical value only. If rounding is necessary, round to the nearest tenth.)

To calculate the dosage of amoxicillin for the infant, first convert the weight from pounds to kilograms, knowing that 1 kilogram equals 2.2 pounds. The infant weighs 22 pounds, which is equivalent to 10 kilograms (22 lb / 2.2 lb/kg). The prescription is for 20 mg/kg/day, so the total daily dosage is 200 mg (10 kg * 20 mg/kg). This total daily dosage is divided into three doses, as it is to be administered every 8 hours, resulting in 66.7 mg per dose (200 mg / 3). The medication is supplied as 250 mg per 5 mL, so to find out how many mL per dose, set up a proportion: 250 mg is to 5 mL as 66.7 mg is to X mL. Solving for X gives us 1.334 mL (66.7 mg * 5 mL / 250 mg), which rounds to 1.3 mL when rounded to the nearest tenth.