What is the epinephrine concentration delivered in a 1.8 mL cartridge of 2% lidocaine with epinephrine 1:100,000 (mg/mL)?

1:100,000 equals 0.01 mg/mL of epinephrine, independent of cartridge volume. (The total epinephrine in 1.8 mL is 0.018 mg.)Other options: 0.02 mg/mL is 1:50,000; the higher values are far too concentrated.Key exam takeaway: 1:100,000 = 0.01 mg/mL epinephrine; total per 1.8 mL cartridge = 0.018 mg.