What is the approximate therapeutic range for trough gentamicin levels?

What is the approximate therapeutic range for trough gentamicin levels?

• A. 0.5-2.0
• B. 2.0-4.0
• C. 10-20
• D. 30-40

Answer: (A)

The question tests knowing how trough levels are used to balance efficacy with toxicity for aminoglycosides. The trough is the lowest concentration in the blood, measured just before the next dose. For gentamicin, keeping that trough low reduces risk of nephrotoxicity and ototoxicity between doses, while allowing sufficiently high peak levels after dosing to kill bacteria. A trough around 0.5 to 2.0 mcg/mL is the typical target range for most intermittent-g dosing regimens. This range minimizes toxicity risk yet still permits effective bacterial killing when peaks are reached after administration. Levels much higher than this carry a greater chance of kidney and inner ear damage, which is why the other ranges (2.0-4.0, 10-20, 30-40 mcg/mL) are not appropriate for trough monitoring.

The question tests knowing how trough levels are used to balance efficacy with toxicity for aminoglycosides. The trough is the lowest concentration in the blood, measured just before the next dose. For gentamicin, keeping that trough low reduces risk of nephrotoxicity and ototoxicity between doses, while allowing sufficiently high peak levels after dosing to kill bacteria.

A trough around 0.5 to 2.0 mcg/mL is the typical target range for most intermittent-g dosing regimens. This range minimizes toxicity risk yet still permits effective bacterial killing when peaks are reached after administration. Levels much higher than this carry a greater chance of kidney and inner ear damage, which is why the other ranges (2.0-4.0, 10-20, 30-40 mcg/mL) are not appropriate for trough monitoring.