What is the number of cartridges of anesthetic that contain 1:100,000 epinephrine that can be used on a healthy patient?

• A. 5.5
• B. 11.1
• C. 22.2
• D. 4.4

Answer: (B)

Understand how much epinephrine is in a cartridge and how much is safe for a healthy patient. A 1:100,000 concentration means 0.01 mg of epinephrine per milliliter. A standard cartridge is 1.8 mL, so each cartridge contains 0.01 mg/mL × 1.8 mL = 0.018 mg of epinephrine. For a healthy patient, the maximum recommended epinephrine per appointment is about 0.2 mg. Dividing the limit by the amount per cartridge gives 0.2 mg ÷ 0.018 mg ≈ 11.1 cartridges. So, 11.1 cartridges can be used in a healthy patient.