Pharmacology · single question
Concentration of a carpule of 1.8 mL of 2% lidocaine with epinephrine 1:100,000 — total amount of epinephrine?
Show answer and explanation
Correct answer: A. 0.018 mg total epinephrine (0.01 mg/mL concentration)
- A. Correct. 1:100,000 = 0.01 mg/mL epinephrine. Total epi = 1.8 mL × 0.01 mg/mL = 0.018 mg.
- B. This value matches the total lidocaine dose (1.8 mL x 20 mg/mL = 36 mg), not the epinephrine dose — a common point of confusion.
- C. This overstates the epinephrine amount by 10x.
- D. This overstates the epinephrine amount by 100x.
Note: 2% lidocaine = 20 mg/mL → total lidocaine = 36 mg per carpule. Epi 1:100,000 = 0.01 mg/mL → total epi = 0.018 mg per carpule.