A 72-year-old man with acute heart failure requires intravenous digoxin; what quantity of infusion solution should be used to dilute a 2 mL ampoule of digoxin 250 microgram/mL solution for injection/infusion?

A 72-year-old man with acute heart failure requires intravenous digoxin; what quantity of infusion solution should be used to dilute a 2 mL ampoule of digoxin 250 microgram/mL solution for injection/infusion?

• A. 250 mL
• B. 1000 mL
• C. 750 mL
• D. 500 mL

Answer: (D)

The key idea is calculating the final dilution by keeping the total amount of drug the same while choosing a practical infusion volume. The ampoule contains 2 mL × 250 micrograms/mL = 500 micrograms of digoxin. If you dilute this into 500 mL of infusion solution, the final concentration becomes 500 micrograms / 500 mL = 1 microgram per mL (0.001 mg/mL). This provides a convenient, controlled infusion concentration for administration. Other volumes would yield concentrations like 2, 0.5, or about 0.667 micrograms per mL, which are less standard and less practical for safe IV infusion. Hence, diluting to 500 mL is the appropriate choice.

The key idea is calculating the final dilution by keeping the total amount of drug the same while choosing a practical infusion volume. The ampoule contains 2 mL × 250 micrograms/mL = 500 micrograms of digoxin. If you dilute this into 500 mL of infusion solution, the final concentration becomes 500 micrograms / 500 mL = 1 microgram per mL (0.001 mg/mL). This provides a convenient, controlled infusion concentration for administration. Other volumes would yield concentrations like 2, 0.5, or about 0.667 micrograms per mL, which are less standard and less practical for safe IV infusion. Hence, diluting to 500 mL is the appropriate choice.