The patient needs 0.1 mcg/kg/min of a drug. The patient weighs 40 kg. If the drug solution is 2 mg/mL, what is the mL/min?

• A. 0.008 mL/min
• B. 0.002 mL/min
• C. 0.04 mL/min
• D. 0.12 mL/min

Answer: (B)

To set an infusion rate from a weight-based dose, first convert the desired dose into a rate in micrograms per minute, then use the drug's concentration to convert that into milliliters per minute.

The patient needs 0.1 mcg/kg/min for 40 kg, so the dose rate is 0.1 × 40 = 4 mcg/min. The drug solution is 2 mg/mL, which is 2000 mcg/mL. The infusion rate in mL per minute is 4 mcg/min ÷ 2000 mcg/mL = 0.002 mL/min.