What is the first step in calculating the amount of Ampicillin to administer to a child who weighs 45lbs 4oz according to a doctor's order of 125mg/kg/day PO divided in doses every 8 hours?

Identify the first necessary step for weight-based dosing The doctor's order is in mg/kg/day, but the child's weight is provided in pounds and ounces. To use the dosage formula (mg * kg), the weight must first be in the correct unit. Perform the first step: Convert 45 lbs 4 oz to kilograms Convert ounces to a decimal of a pound: 4 oz / 16 oz = 0.25 lbs Total weight in pounds: 45.25 lbs Convert pounds to kilograms: 45.25 / 2.2 = 20.568... kg = 20.6 kg