SULFINPYRAZONE
Clinical safety rating
safeAnimal studies have demonstrated safety
Competitive inhibitor of tubular organic anion transport, increasing uric acid excretion; also inhibits platelet aggregation.
| Metabolism | Primarily hepatic via oxidation and conjugation; major metabolite is sulfinpyrazone sulfide. |
| Excretion | Renal: ~90% (50% unchanged, 50% as glucuronide and other metabolites); Biliary/fecal: ~10% |
| Half-life | 2-5 hours (terminal elimination half-life; prolonged in renal impairment to up to 10 hours) |
| Protein binding | 98-99% (primarily to albumin) |
| Volume of Distribution | 0.15-0.25 L/kg (low Vd, consistent with high protein binding and limited tissue distribution) |
| Bioavailability | Oral: 80-90% (well absorbed; decreased with food) |
| Onset of Action | Oral: 1-2 hours (time to peak uricosuric effect after a single dose) |
| Duration of Action | Oral: 4-6 hours (uricosuric effect; longer with multiple dosing due to active metabolite) |
| Molecular Weight | 404.48 |
100-200 mg orally twice daily, initially, then increase to 200-400 mg twice daily.
| Dosage form | CAPSULE |
| Renal impairment | GFR >50 mL/min: no adjustment. GFR 10-50 mL/min: reduce dose by 50%. GFR <10 mL/min: avoid use. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50%. Child-Pugh C: avoid use. |
| Pediatric use | Safety and efficacy not established; use not recommended. |
| Geriatric use | Start at lower end of dosing range (100-200 mg daily) and titrate cautiously due to increased risk of renal impairment and drug interactions. |
| 1st trimester | Avoid; associated with folate antagonism and potential teratogenicity (neural tube defects). |
| 2nd trimester | Avoid; risk of maternal anemia and fetal folate depletion. |
| 3rd trimester | Avoid; may cause premature closure of ductus arteriosus, neonatal bleeding, and renal dysfunction. |
Clinical note
Salicylates antagonize the uricosuric effect Can cause GI upset and blood dyscrasias.
| Placental transfer | Crosses placenta; achieves fetal plasma concentrations ~50% of maternal levels. |
| Breastfeeding | Enters breast milk in low concentrations; may cause hemolytic anemia in G6PD-deficient infants. Use with caution, preferably avoid in nursing mothers of neonates or G6PD-deficient infants. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Sulfinpyrazone is contraindicated in pregnancy. Animal studies have shown teratogenic effects, and there are no adequate human studies. First trimester exposure may carry a risk of congenital malformations. Second and third trimester use may cause adverse fetal effects including premature closure of the ductus arteriosus, oligohydramnios, and renal dysfunction. |
| Fetal Monitoring | Monitor maternal renal function, hepatic function, and complete blood count periodically. Fetal ultrasound should be considered to assess growth and amniotic fluid volume if exposure occurs in the second or third trimester. |
| Fertility Effects | Sulfinpyrazone may impair fertility in females by inhibiting ovulation. In males, it may affect spermatogenesis. Reversible upon discontinuation. |
■ FDA Black Box Warning
None.
| Common Effects | GI upset |
| Serious Effects |
Hypersensitivity to sulfinpyrazone or other sulfonamidesActive peptic ulcer diseaseBlood dyscrasiasSevere hepatic or renal impairment
| Precautions | Risk of acute gouty attacks during initial therapy, Uricosuric effect may lead to urolithiasis; maintain adequate hydration and urine alkalinization, Possible cross-allergenicity with sulfonamides, Monitor renal function and complete blood counts |
| Food/Dietary | Avoid high-purine foods (e.g., organ meats, anchovies, sardines, beer) as they may reduce efficacy. Maintain adequate hydration; alcohol consumption should be minimized as it can increase uric acid levels. |
| Clinical Pearls | Sulfinpyrazone is a uricosuric agent used for chronic gout; avoid in acute gout attack. Monitor renal function and uric acid levels. Contraindicated in peptic ulcer disease due to GI irritation. May potentiate warfarin and sulfonylureas; adjust doses accordingly. |
| Patient Advice | Take with food or milk to reduce GI upset. · Drink plenty of fluids (at least 2-3 liters daily) to prevent kidney stones. · Avoid aspirin and other salicylates as they reduce effectiveness. · Report any signs of bleeding, bruising, or abdominal pain immediately. · Do not stop abruptly; discuss with your doctor. |
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