What is a normal trough range for vancomycin in adults?

• A. 5-10 mcg/mL
• B. 10-20 mcg/mL
• C. 20-30 mcg/mL
• D. 30-40 mcg/mL

Answer: (B)

Trough levels measure the lowest concentration of a drug in the blood just before the next dose and are used to gauge how much exposure the body is getting over time, aiming to balance effective infection control with minimizing toxicity. For vancomycin in adults, the typical therapeutic trough range is about 10-20 mcg/mL. Values below this range can be subtherapeutic and may fail to treat the infection adequately, while values above this range increase the risk of nephrotoxicity and other toxic effects. In many serious infections, clinicians target the higher end (around 15-20) to ensure sufficient exposure, but the broad, commonly cited window remains 10-20 mcg/mL.