Gout Prevention in an Elderly Patient

David M. Quillen, MD

Disclosures

February 13, 2001

Question

I am treating a 81-year-old male patient with a history of recurrent gouty arthritis. His serum uric acid level is 9.4 mg/dL. Two 24-hour urine collections have revealed between 200 and 300 mg of uric acid per 24 hours and a creatinine clearance of 66 mL/min. He is taking Azulfidine for ulcerative colitis. Is it safe to prescribe probenecid given his age and mild renal insufficiency, or would it be better to prescribe allopurinol?

Response from David M. Quillen, MD

Based upon the 24-hour uric acid levels, this patient is clearly an undersecretor rather than an overproducer, with diminished renal function in a range that is probably normal for his advanced age. If this patient were having more than 4 episodes of gout a year, allopurinol would generally be the recommended preventative agent. The reasons for using allopurinol rather than the uricosuric drugs (probenecid or sulfinpyrazone [Anturane]) include age, renal function, and prevention of renal calculi, which is a major side effect of the uricosuric agents. Uricosuric drugs increase renal secretion of uric acid by competitively inhibiting the active reabsorption of uric acid at the proximal convoluted tubule, thereby facilitating urinary excretion of uric acid and decreasing plasma uric acid concentrations. Recommendations for use are: (1) age less than 60 years and (2) good to normal renal function. Uricosuric agents will be most effective when used in such patients.

A creatinine clearance of 66 mL/min is probably normal for a man 81 years old, but significantly diminished from the ideal 100-120 mL/min that works best with the uricosuric agents. The lower limit of creatinine clearance believed to be safe for probenecid use is 50 mL/min.

Allopurinol inhibits the enzyme xanthine oxidase, which blocks the metabolism of hypoxanthine and xanthine (oxypurines) to uric acid. The oxypurines are easily eliminated by the kidneys, do not cause gout, and do not cause uric acid stones. However, for elderly patients and for those with renal impairment, a decreased dose is indicated and generally considered safe. Based upon his creatinine clearance, the recommended dose would be 200 mg/day instead of the usual 300 mg/day for this patient. Finally, there are no reported drug interactions between Azulfidine and the gout medications.

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