Topics from the

Book of Arthritis

Some drugs lower the uric acid level by increasing the amount of uric acid passed in the urine. They help dissolve tophi and prevent uric acid deposits in joints. Probenecid (Benemid, Parbenem, Probalan) and sulfinpyrazone (Anturane). Common side effects include nausea, skin rash, stomach upset, or headaches. Increase water intake to about 10 x 8 ounce glasses per day.  Avoid aspirin with these drugs because it blocks their effects on the kidneys. At first, probenecid or sulfinpyrazone may increase the risk of kidney stones by increasing the uric acid content in the urine.  Maintenance of a large volume of alkaline urine increases the solubility of uric acid and thus reduces the risk of stone formation in the kidneys.

Adding baking soda to the water will make the urine more alkaline, increase the solubility of uric acid and help to reduce the risk of urinary tract stones.

The drug is indicated in patients with disabling attacks of gout. When uric acid concentrations exceed 9 mg/dL increased joint changes and renal complications are likely and treatment should begin even in the absence of gout attacks.  The goal of probenecid therapy is to lower serum urate concentrations to about 6 mg/dL. By decreasing serum urate concentrations, probenecid prevents or reduces chronic joint changes and tophi formation, eventually reduces the frequency of acute gout attacks, and may improve renal function in gouty patients.

Since probenecid has no analgesic or anti-inflammatory activity, it is of no value in the treatment of acute gout attacks and will exacerbate and prolong inflammation during the acute phase. Probenecid should not be started until 2—3 weeks after an acute gout attack. The drug may increase the frequency of acute attacks during the first 6—12 months of therapy, even when normal or subnormal serum urate concentrations have been maintained. Acute attacks usually become less severe and are of briefer duration after several months of probenecid therapy. During these acute attacks, probenecid should be continued without changing dosage.   

The drug is not effective renal insufficiency exists, particularly in patients with  a creatinine clearance of less than 50 mL/minute. Since uricosuric agents tend to increase urinary uric acid concentrations and the risk of stone formation, they should be avoided; allopurinol is preferred in patients with urinary uric acid excretion of greater than 900 mg/day or with gouty nephropathy, urinary tract stones or obstruction, or azotemia.  Patients who are refractory to or cannot tolerate probenecid may respond to allopurinol. The activity of allopurinol and uricosurics is additive and when administered concomitantly, smaller doses of each drug can be used. Combined use of the 2 types of drugs is especially effective in the presence of tophaceous deposits.