Benemid, Benuryl , Probalan, SK-Probenecid
Classifications: antigout agent; sulfonamide; uricosuric agent; Therapeutic:antigout; uricosuric agent
Pregnancy Category: B
0.5 g tablet
Sulfonamide-derivative renal tubular blocking agent. In sufficiently high doses, competitively inhibits renal tubular reabsorption
of uric acid, thereby promoting its excretion and reducing serum urate levels.
Prevents formation of new tophaceous deposits and causes gradual shrinking of old tophi by preventing uric acid build-up
in the serum and tissues. As an additive to penicillin, it increases the serum concentration of the antibiotic, and also
prolongs the serum concentration of the penicillins.
Hyperuricemia in chronic gouty arthritis and tophaceous gout.
Adjuvant to therapy with penicillin G and penicillin analogs to elevate and prolong plasma concentrations of these antibiotics;
to promote uric acid excretion in hyperuricemia secondary to administration of thiazides and related diuretics, furosemide,
ethacrynic acid, pyrazinamide.
Blood dyscrasias; uric acid kidney stones; during or within 23 wk of acute gouty attack; overexcretion of uric acid
(>1000 mg/d); patients with creatinine clearance <50 mg/min; use with penicillin in presence of known renal impairment;
use for hyperuricemia secondary to cancer chemotherapy. Safe use in children <2 y is not established.
History of peptic ulcer; pregnancy (category B), lactation.
Route & Dosage
Adult: PO 250 mg b.i.d. for 1 wk, then 500 mg b.i.d. (max: 3 g/d)
Adjunct for Penicillin or Cephalosporin Therapy
Adult: PO 500 mg q.i.d. or 1 g with single dose therapy (e.g., gonorrhea)
Child (214 y or <50 kg): PO 2540 mg/kg/d in 4 divided doses
- Therapy is usually not initiated during an acute gouty attack. Consult physician.
- Minimize GI adverse effects by giving after meals, with food, milk, or antacid (prescribed). If symptoms persist, dosage
reduction may be required.
- Give with a full glass of water if not contraindicated.
- Be aware that physician may prescribe concurrent prophylactic doses of colchicine for first 36 mo of therapy because
frequency of acute gouty attacks may increase during first 612 mo of therapy.
Adverse Effects (≥1%)Body as a Whole:
Flushing, dizziness, fever, anaphylaxis. CNS: Headache. GI: Nausea, vomiting, anorexia,
sore gums, hepatic necrosis (rare). Urogenital:
Urinary frequency. Hematologic:
Anemia, hemolytic anemia (possibly related to G6PD deficiency), aplastic anemia (rare). Musculoskeletal:
Exacerbations of gout
, uric acid kidney stones
Dermatitis, pruritus. Respiratory: Respiratory depression.
Diagnostic Test Interference
False-positive urine glucose tests are possible with Benedict's solution or Clinitest [glucose oxidase methods not affected (e.g., Clinistix, TesTape)].
may decrease uricosuric activity; may decrease methotrexate
elimination, causing increased toxicity; decreases nitrofurantoin
efficacy and increases its toxicity. Decreases clearance of penicillins, cephalosporins, and NSAIDs.
Readily from GI tract. Onset:
30 min. Peak:
24 h. Duration:
8 h. Distribution:
Crosses placenta. Metabolism:
In liver. Elimination:
In urine. Half-Life:
Assessment & Drug Effects
- Decrease daily dosage with caution by 0.5 g q6mo to lowest effective dosage that maintains stable serum urate levels when
gouty attacks have been absent for 6 mo or more and serum urate levels are controlled.
- Lab tests: Periodic serum urate levels, Hct and Hgb, and urinalysis. Determine acidbase balance periodically when
urinary alkalinizers are used. Some physicians prescribe acetazolamide at bedtime to keep urine alkaline and dilute throughout
- Patients taking sulfonylureas may require dosage adjustment. Probenecid enhances hypoglycemic actions of these drugs (see
DIAGNOSTIC TEST INTERFERENCES).
- Expect urate tophaceous deposits to decrease in size. Classic locations are in cartilage of ear pinna and big toe, but they
can occur in bursae, tendons, skin, kidneys, and other tissues.
Patient & Family Education
- Drink fluid liberally (approximately 3000 mL/d) to maintain daily urinary output of at least 2000 mL or more. This is important
because increased uric acid excretion promoted by drug predisposes to renal calculi.
- Physician may advise restriction of high-purine foods during early therapy until uric acid level stabilizes. Foods high
in purine include organ meats (sweetbreads, liver, kidney), meat extracts, meat soups, gravy, anchovies, and sardines. Moderate
amounts are present in other meats, fish, seafood, asparagus, spinach, peas, dried legumes, wild game.
- Avoid alcohol because it may increase serum urate levels.
- Do not stop taking drug without consulting physician. Irregular dosage schedule may sharply elevate serum urate level and
precipitate acute gout.
- Be aware that lifelong therapy is usually required in patients with symptomatic hyperuricemia. Keep scheduled appointments
with physician and for kidney function and hematology lab work.
- Report symptoms of hypersensitivity to physician. Discontinuation of drug is indicated.
- Do not take aspirin or other OTC medications without consulting physician. If a mild analgesic is required, acetaminophen
is usually allowed.