How much epinephrine is delivered in one 1.8 mL cartridge of lidocaine containing epinephrine 1:100,000? (Concentration question, expressed as mg/mL.)

A 1:100,000 dilution means 1 g in 100,000 mL = 0.01 mg per mL. The concentration is independent of cartridge volume.Other options: 0.02 mg/mL corresponds to 1:50,000; 0.005 mg/mL corresponds to 1:200,000. The 0.2 and 1 mg/mL values are far too concentrated.Key exam takeaway: 1:100,000 = 0.01 mg/mL; 1:50,000 = 0.02 mg/mL; 1:200,000 = 0.005 mg/mL. Total dose = concentration x volume (0.018 mg per 1.8 mL cartridge).