SULFINPYRAZONE

SULFINPYRAZONE
(sul-fin-peer'a-zone)
Antazone , Anturan , Anturane, Apo-Sulfinpyrazone , Novopyrazone 
Classifications: antigout agent; uricosuric;
Therapeutic: antigout

Prototype: Probenecid
Pregnancy Category: C

Availability

100 mg tablets; 200 mg capsules

Action

Potent renal tubular blocking agent of uric acid in the kidney that lowers its serum blood level. Like all uricosurics, low doses may inhibit tubular secretion of uric acid and cause urate retention. Inhibits release of adenosine diphosphate and 5-hydroxytryptophan, and thus decreases platelet adhesiveness and increases platelet survival time; has no effect on prothrombin or blood clotting time.

Therapeutic Effect

Promotes urinary excretion of uric acid and reduces serum urate levels by competitively inhibiting tubular reabsorption of uric acid in the kidney.

Uses

Maintenance therapy in chronic gouty arthritis and tophaceous gout.

Unlabeled Uses

Drug-induced hyperuricemia, to decrease platelet aggregation and increase their survival in prevention of TIAs and stroke.

Contraindications

Known hypersensitivity to phenylbutazone, or pyrazoline derivatives or salicylates; active peptic ulcer; concurrent administration of salicylates; blood dyscrasias; patients with creatinine clearance <50 mg/min, treatment of hyperuricemia secondary to neoplastic disease or cancer chemotherapy; bone marrow suppression; hematologic disease; nephrolithiasis.

Cautious Use

NSAID hypersensitivity; impaired kidney function; severe hepatic disease; history of healed peptic ulcer; concurrent use of anticoagulant therapy; thrombocytopenia; use in conjunction with sulfonamides and sulfonylureas; pregnancy (category C), lactation.

Route & Dosage

Gout
Adult: PO 100–200 mg b.i.d. for 1 wk, then increase to 200–400 mg b.i.d., may reduce to 200 mg/d after serum urate levels are controlled (max: 800 mg/d)

Inhibition of Platelet Aggregation
Adult: PO 200 mg t.i.d. or q.i.d.

Administration

Oral
  • Give with meals, milk, or antacid (prescribed) to prevent local drug irritant effect. Severity and frequency of symptoms increase with dosage. Persistence of GI symptoms may require discontinuation of drug.
  • Ensure fluid intake sufficient to support urinary output of at least 2000–3000 mL/d during early therapy (consult physician). Also alkalinize urine (e.g., with large doses vitamin C) to increase solubility of uric acid and minimize risk of uric acid stones.

Adverse Effects (≥1%)

GI: Nausea, vomiting, diarrhea, epigastric pain, blood loss, reactivation or aggravation of peptic ulcer, jaundice. CNS: Ataxia, dizziness, vertigo, convulsions, coma. Special Senses: Tinnitus. Body as a Whole: Edema, labored respirations, hypersensitivity, reactions (skin rashes, fever). Urogenital: Precipitation of acute gout, urolithiasis, renal colic.

Diagnostic Test Interference

Sulfinpyrazone decreases urinary excretion of aminohippuric acid and phenolsulfonphthalein.

Interactions

Drug: May decrease efficacy of nitrofurantoin for UTI and increase its systemic toxicity. May displace sulfonylureas from protein binding and increase risk of hypoglycemia; may augment prothrombin time increased by warfarin; cholestyramine decreases absorption of sulfinpyrazone; aspirin may inhibit uricosuric effects of sulfinpyrazone.

Pharmacokinetics

Absorption: Readily absorbed from GI tract. Peak: 1–2 h. Duration: 4–6 h; may persist up to 10 h. Metabolism: In liver to active and inactive metabolites. Elimination: Slowly in urine; 5% in feces. Half-Life: 3 h.

Nursing Implications

Assessment & Drug Effects

  • Monitor therapy using serum urate levels (lower to about 6 mg/dL) to reduce joint changes, tophi formation, and frequency of acute attacks and to improve kidney function.
  • Lab tests: Obtain periodic blood cell counts during prolonged therapy. Also kidney function, particularly with renal impairment. Monitor PT and INR with concurrent warfarin use.
  • Frequency of acute gouty attacks may increase during first 6–12 mo of therapy, even when serum urate levels appear to be controlled. Concurrent prophylactic doses of colchicine may be prescribed during first 3–6 mo of treatment to prevent or lessen severity of attacks.

Patient & Family Education

  • Remain under close medical supervision; therapy is continued indefinitely.
  • Do not experiment with dosage; subtherapeutic doses may enhance urate retention and large doses may increase risk of toxicity.
  • Continue medication without interruption even during acute gouty attack. Contact physician for concomitant treatment with full therapeutic doses of colchicine or other antiinflammatory agent.
  • Avoid aspirin-containing medications. If an analgesic is required (in patients with normal kidney function), acetaminophen is generally recommended.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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