Probenecid

Probenecid is a uricosuric medication used to treat hyperuricemia and gout. It reduces the concentration of uric acid in the blood by inhibiting its reabsorption in the proximal renal tubules, increasing urinary excretion of uric acid. In addition, probenecid inhibits active tubular secretion of weak acids, including certain antibiotics such as penicillin, resulting in higher and more prolonged plasma concentrations of those drugs.

Indications include long-term management of gout and hyperuricemia. It is also used as an adjunct to penicillin therapy to prolong penicillin exposure, particularly historically for infections such as syphilis or gonorrhea, though its use for this purpose has declined with modern antibiotics.

Pharmacokinetics: Probenecid is administered orally and well absorbed. It is largely protein-bound and eliminated primarily by the kidneys, with a half-life prolonged in renal impairment. Dose must be adjusted in kidney disease. It is contraindicated in significant kidney impairment or conditions predisposing to uric acid stones.

Adverse effects include GI upset, rash or hypersensitivity reactions, and increased risk of kidney stone formation due to higher urinary uric acid. Rare hematologic or hypersensitivity syndromes may occur. Interactions: the uricosuric effect can be antagonized by low-dose aspirin and other NSAIDs; it can raise blood levels of drugs eliminated by renal secretion (penicillins, methotrexate, some cephalosporins).