For CrCl < 60 mL/min, which drug should have its dose reduced due to CNS adverse effects?

• A. Diclofenac
• B. Gabapentin
• C. Metformin
• D. Pregabalin

Answer: (D)

Renal impairment changes drug clearance, so medicines cleared by the kidneys need lower doses to prevent buildup and central nervous system effects. Gabapentinoids are eliminated unchanged by the kidneys and are known for CNS side effects such as dizziness, somnolence, and confusion, which become more likely as exposure increases.

Pregabalin is cleared via the kidneys, and when the creatinine clearance is below 60 mL/min, the dose should be reduced to avoid these CNS adverse effects. The risk of sedation, dizziness, and cognitive impairment rises with higher drug exposure, so lowering the dose helps mitigate these risks in patients with CrCl < 60.

While gabapentin also requires renal dosing adjustments, this scenario emphasizes pregabalin's need for dose reduction due to CNS effects in reduced renal function.