For probenecid in CrCl less than 30 mL/min, what is the rationale behind avoiding it?

• A. Loss of effectiveness
• B. GI toxicity
• C. Sedation
• D. Hypertension

Answer: (A)

Probenecid works by increasing uric acid excretion through action in the proximal tubule, a mechanism that depends on functional kidney tubules and adequate filtration. When the creatinine clearance is severely reduced (below 30 mL/min), the kidneys can’t excrete efficiently, so the uricosuric effect of probenecid is blunted and it won’t meaningfully lower uric acid or prevent gout flares. In this setting, using probenecid is avoided because it loses its effectiveness. While there can be other risks with renal impairment, the primary reason here is that the drug simply won’t work well enough to be beneficial.