When treating endocarditis with gentamicin, which monitoring is essential to ensure efficacy and safety?

• A. Blood pressure
• B. Serum potassium
• C. Peak and trough levels
• D. Blood glucose

Answer: (C)

Gentamicin works best when the drug concentration at the bacteria is high enough to kill, but too high levels raise the risk of kidney and ear toxicity. Because of this balance, monitoring is done with peak and trough levels. The peak level shows whether the dose achieves a bactericidal concentration, while the trough level indicates how much drug remains in the body before the next dose to minimize toxicity. This therapeutic drug monitoring is crucial in serious infections like endocarditis where dosing may need adjustment for patient factors (kidney function, volume of distribution) and to preserve safety. Blood pressure, potassium, and glucose aren’t the key measures for ensuring gentamicin efficacy and safety, whereas peak and trough levels directly guide dosing and toxicity risk.