Which drug should be avoided in older adults with impaired kidney function (eGFR < 60 mL/min) due to CNS toxicity risk?

• A. Duloxetine
• B. Gabapentin
• C. Baclofen
• D. Levetiracetam

Answer: (C)

In older adults, drugs eliminated by the kidneys can accumulate when kidney function is reduced, increasing the risk of adverse effects, especially CNS toxicity. Baclofen is a muscle relaxant that is cleared almost entirely by the kidneys. When eGFR is under 60, baclofen clearance drops, leading to higher drug levels and a greater chance of CNS-related problems such as drowsiness, confusion, dizziness, ataxia, and even seizures. Because of this strong risk in renal impairment, the Beers Criteria flags baclofen for avoidance in older adults with reduced kidney function. The other options either have dosing adjustments available for CKD or carry less pronounced CNS toxicity risk at this level of impairment, so they are not the primary avoidant choice in this scenario.