Probenecid

INDICATIONS AND USAGE 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.

DOSAGE AND ADMINISTRATION Gout Therapy with probenecid should not be started until an acute gouty attack has subsided. However, if an acute attack is precipitated during therapy, probenecid may be continued without changing the dosage, and full therapeutic dosage of colchicine or other appropriate therapy should be given to control the acute attack. The recommended adult dosage is 250 mg (1/2 tablet of probenecid) twice a day for one week, followed by 500 mg (1 tablet) twice a day thereafter. Some degree of renal impairment may be present in patients with gout. A daily dosage of 1000 mg may be adequate. However, if necessary, the daily dosage may be increased by 500 mg increments every 4 weeks within tolerance (and usually not above 2000 mg per day) if symptoms of gouty arthritis are not controlled or the 24 hour uric acid excretion is not above 700 mg. As noted, probenecid may not be effective in chronic renal insufficiency, particularly when the glomerular filtration rate is 30 mL/minute or less. Gastric intolerance may be indicative of overdosage, and may be corrected by decreasing the dosage. As uric acid tends to crystallize out of an acid urine, a liberal fluid intake is recommended, as well as sufficient sodium bicarbonate (3 to 7.5 g daily), or potassium citrate (7.5 g daily) to maintain an alkaline urine (see PRECAUTIONS ). Alkalization of the urine is recommended until the serum urate level returns to normal limits and tophaceous deposits disappear, i.e., during the period when urinary excretion of uric acid is at a high level. Thereafter, alkalization of the urine and the usual restriction of purine-producing foods may be somewhat relaxed. Probenecid should be continued at the dosage that will maintain normal serum urate levels. When acute attacks have been absent for 6 months or more and serum urate levels remain within normal limits, the daily dosage may be decreased by 500 mg every 6 months. The maintenance dosage should not be reduced to the point where serum urate levels tend to rise. Probenecid and Penicillin Therapy (General) Adults The recommended dosage is 2000 mg (4 tablets of probenecid) daily in divided doses. This dosage should be reduced in older patients in whom renal impairment may be present. Children 2 to 14 years of age Initial dose: 25 mg/kg body weight ( or 0.7 g/square meter body surface). Maintenance dose: 40 mg/kg body weight ( or 1.2 g/square meter body surface) per day, divided into 4 doses. For children weighing more than 50 kg (110 lb) the adult dosage is recommended. Probenecid is contraindicated in children under 2 years of age. The PSP excretion test may be used to determine the effectiveness of probenecid in retarding penicillin excretion and maintaining therapeutic levels. The renal clearance of PSP is reduced to about one-fifth the normal rate when dosage of probenecid is adequate. Penicillin Therapy (Gonorrhea)* In uncomplicated gonococcal infections in men and women (urethral, cervical, rectal), 1 g of probenecid should be given orally with 4.8 million units of aqueous procaine penicillin G ** (given IM), or 3 g of amoxicillin ** (given orally), or 3.5 g of ampicillin ** (given orally). For further guidance, see CDC recommendations for definition of regimens of choice, alternative regimens, treatment of hypersensitive patients, and other aspects of therapy. * Recommended by the Centers for Disease Control, U.S. Department of Health and Human Services, Public Health Service (Morbidity and Mortality Weekly Report Supplement, Volume 34, Number 4S, October 18, 1985). ** See package circulars of manufacturers for detailed information about CONTRAINDICATIONS , WARNINGS , PRECAUTIONS , and ADVERSE REACTIONS .

CONTRAINDICATIONS 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.

ADVERSE REACTIONS The following adverse reactions have been observed and within each category are listed in order of decreasing severity. Central Nervous System: headache, dizziness. Metabolic: precipitation of acute gouty arthritis. Gastrointestinal: hepatic necrosis, vomiting, nausea, anorexia, sore gums. Genitourinary: nephrotic syndrome, uric acid stones with or without hematuria, renal colic, costovertebral pain, urinary frequency. Hypersensitivity: anaphylaxis, fever, urticaria, pruritus. Hematologic: aplastic anemia, leukopenia, hemolytic anemia which in some patients could be related to genetic deficiency of glucose-6-phosphate dehydrogenase in red blood cells, anemia. Integumentary: dermatitis, alopecia, flushing. To report SUSPECTED ADVERSE REACTIONS, contact Teva at 1-888-838-2872 or FDA at 1-800-FDA-1088 or http://www.fda.gov/medwatch.

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 ). The uricosuric action of probenecid is also antagonized by pyrazinamide. Probenecid produces an insignificant increase in free sulfonamide plasma concentrations, but a significant increase in total sulfonamide plasma levels. Since probenecid decreases the renal excretion of conjugated sulfonamides, plasma concentrations of the latter should be determined from time to time when a sulfonamide and probenecid are coadministered for prolonged periods. Probenecid may prolong or enhance the action of oral sulfonylureas and thereby increase the risk of hypoglycemia. It has been reported that patients receiving probenecid require significantly less thiopental for induction of anesthesia. In addition, ketamine and thiopental anesthesia were significantly prolonged in rats receiving probenecid. The concomitant administration of probenecid increases the mean plasma elimination half-life of a number of drugs which can lead to increased plasma concentrations. These include agents such as indomethacin, acetaminophen, naproxen, ketoprofen, meclofenamate, lorazepam, and rifampin. Although the clinical significance of this observation has not been established, a lower dosage of the drug may be required to produce a therapeutic effect, and increases in dosage of the drug in question should be made cautiously and in small increments when probenecid is being coadministered. Although specific instances of toxicity due to this potential interaction have not been observed to date, physicians should be alert to this possibility. Probenecid given concomitantly with sulindac had only a slight effect on plasma sulfide levels, while plasma levels of sulindac and sulfone were increased. Sulindac was shown to produce a modest reduction in the uricosuric action of probenecid, which probably is not significant under most circumstances. In animals and in humans, probenecid has been reported to increase plasma concentrations of methotrexate (see WARNINGS ). Falsely high readings for theophylline have been reported in an in vitro study, using the Schack and Waxler technique, when therapeutic concentrations of theophylline and probenecid were added to human plasma.

DESCRIPTION: Probenecid is a uricosuric and renal tubular transport blocking agent. The chemical name for probenecid is 4-[(dipropylamino) sulfony1] benzoic acid. It has the following structural formula: Probenecid, USP is a white or nearly white, fine, crystalline powder. Probenecid is soluble in dilute alkali, in alcohol, in chloroform, and in acetone; it is practically insoluble in water and in dilute acids. Each tablet for oral administration contains 500 mg of probenecid and the following inactive ingredients: Microcrystalline cellulose, corn starch, sodium starch glycolate, povidone, colloidal silicon dioxide, magnesium stearate, sodium lauryl sulfate, polyvinyl alcohol, titanium dioxide, polyethylene glycol, talc, D&C Yellow #10 Aluminum Lake, FD&C Yellow #6 Aluminum Lake, and FD&C Blue #2 Aluminum Lake. the following structural formula for probenecid is 4-[(dipropylamino) sulfony1] benzoic acid.

HOW SUPPLIED Probenecid Tablets, USP are available containing 500 mg of Probenecid, USP. The tablets are capsule shaped, film-coated yellow, debossed LCI on one side and 1367 on the other side. They are available as follows: NDC 10135-0541-01 bottles of 100 tablets NDC 10135-0541-10 bottles of 1000 tablets STORE AT 20 ̊ to 25 ̊C (68 ̊-77 ̊F) [See USP Controlled Room Temperature] PROTECT FROM LIGHT. Dispense in a well closed, light-resistant container using a child-resistant closure as defined in the USP. MANUFACTURED BY LANNETT COMPANY, INC. PHILADELPHIA, PA 19136 DISTRIBUTED BY MARLEX PHARMACEUTICALS, INC. NEW CASTLE, DE 19720 Made in the USA Rev.1 10/14LAN