Digoxin elixir 125 mcg PO daily is prescribed. The drug is available in a 60 mL bottle labeled “Digoxin elixir 0.05 mg/mL.” How many mL should be administered?

Digoxin elixir 125 mcg PO daily is prescribed. The drug is available in a 60 mL bottle labeled “Digoxin elixir 0.05 mg/mL.” How many mL should be administered?

• A. 1.0
• B. 2.5
• C. 1.5
• D. 3.0

Answer: (B)

Dosing with liquids relies on matching units and using the concentration to find the required volume. Convert the prescribed dose to the same unit as the drug’s concentration: 125 mcg is 0.125 mg. The elixir concentration is 0.05 mg/mL, so the volume needed is 0.125 mg ÷ 0.05 mg/mL = 2.5 mL. Administer 2.5 mL. Quick check: 2.5 mL × 0.05 mg/mL = 0.125 mg = 125 mcg.

Dosing with liquids relies on matching units and using the concentration to find the required volume. Convert the prescribed dose to the same unit as the drug’s concentration: 125 mcg is 0.125 mg. The elixir concentration is 0.05 mg/mL, so the volume needed is 0.125 mg ÷ 0.05 mg/mL = 2.5 mL. Administer 2.5 mL. Quick check: 2.5 mL × 0.05 mg/mL = 0.125 mg = 125 mcg.