American Board of Internal Medicine (ABIM) Certification Practice Exam

Which alternative first-line urate-lowering agent is appropriate for patients unable to tolerate xanthine oxidase inhibitors?

1. Probenecid

2. Allopurinol

3. Febuxostat

4. Colchicine

The correct answer is: Probenecid

Probenecid is a first-line urate-lowering agent that is particularly suitable for patients who cannot tolerate xanthine oxidase inhibitors like allopurinol and febuxostat. This medication works by enhancing the renal excretion of uric acid, thus lowering serum urate levels in the body. It is especially effective in patients who have underexcretion of uric acid, which is a common cause of hyperuricemia and gout. In contrast, the other options are all associated with xanthine oxidase inhibition or do not primarily function as urate-lowering agents in the way probenecid does. Allopurinol and febuxostat are both xanthine oxidase inhibitors that reduce uric acid production but are not suitable for patients with intolerance to that class of medications. Colchicine, while useful for managing acute gout flares and prevention, does not effectively lower uric acid levels in the long term and is not considered a urate-lowering therapy. Thus, for patients who experience adverse effects with xanthine oxidase inhibitors, probenecid provides an alternative approach by facilitating the excretion of uric acid rather than inhibiting its production. This makes it a valuable option for managing hyper