A pediatric patient weighing 66 pounds requires naloxone 0.1 mg/kg. If naloxone stock is 400 micrograms per mL, how many milliliters should be administered? (Round to the nearest hundredth)

• A. 5.00
• B. 7.50
• C. 8.75
• D. 9.00

Answer: (B)

The main idea here is converting weight to kilograms and then using mg/kg to find the total milligrams needed, followed by converting concentration to a volume. First, convert the patient’s weight to kilograms: 66 lb is about 30 kg (66 ÷ 2.2046 ≈ 29.9, rounded to 30). The prescribed dose is 0.1 mg per kg, so for 30 kg the total dose is 0.1 × 30 = 3 mg. The naloxone stock is 400 mcg/mL, which is 0.4 mg/mL. To find the volume to administer, divide the dose by the concentration: 3 mg ÷ 0.4 mg/mL = 7.5 mL. Rounding to the nearest hundredth gives 7.50 mL. Therefore, you should administer 7.50 mL.