Collect trough 0-1h before 3rd dose if abnormal/fluctuating renal function.
Target trough 15-20mcg/mL for most serious infections, 20-25mcg/mL for meningitis.
If trough low, increase dose OR decrease dosing interval (generally suggested to not exceed 2g/dose, but may be indicated in certain circumstances).
If trough >20, increase dosing interval or decrease dose.