Probenecid

Probenecid tablets are indicated for the treatment of the hyperuricemia associated with gout and gouty arthritis. As an adjuvant to therapy with penicillin or with ampicillin, methicillin, oxacillin, cloxacillin, or nafcillin, for elevation and prolongation of plasma levels by whatever route the antibiotic is given.

Hypersensitivity to probenecid. Children under 2 years of age. Not recommended in persons with known blood dyscrasias or uric acid kidney stones. Therapy with probenecid should not be started until an acute gouty attack has subsided.

Exacerbation of gout following therapy with probenecid may occur; in such cases colchicine or other appropriate therapy is advisable. Probenecid increases plasma concentrations of methotrexate in both animals and humans. In animal studies, increased methotrexate toxicity has been reported. If probenecid is given with methotrexate, the dosage of methotrexate should be reduced and serum levels may need to be monitored.

In patients on probenecid the use of salicylates in either small or large doses is contraindicated because it antagonizes the uricosuric action of probenecid. The biphasic action of salicylates in the renal tubules accounts for the so-called “paradoxical effect” of uricosuric agents. In patients on probenecid who require a mild analgesic agent the use of acetaminophen rather than small doses of salicylates would be preferred.

Rarely, severe allergic reactions and anaphylaxis have been reported with the use of probenecid. Most of these have been reported to occur within several hours after readministration following prior usage of the drug. The appearance of hypersensitivity reactions requires cessation of therapy with probenecid. Use in Pregnancy Probenecid crosses the placental barrier and appears in cord blood. The use of any drug in women of childbearing potential requires that the anticipated benefit be weighed against possible hazards.

Drug Interactions When probenecid is used to elevate plasma concentrations of penicillin or other beta-lactams, or when such drugs are given to patients taking probenecid therapeutically, high plasma concentrations of the other drug may increase the incidence of adverse reactions associated with that drug. In the case of penicillin or other beta-lactams, psychic disturbances have been reported. The use of salicylates antagonizes the uricosuric action of probenecid (see WARNINGS ).