SULFINPYRAZONE
Clinical safety rating: safe
Animal 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) |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Salicylates antagonize the uricosuric effect Can cause GI upset and blood dyscrasias.
| Breastfeeding | Sulfinpyrazone is excreted into breast milk in small amounts. The M/P ratio is unknown. Due to the risk of serious adverse reactions in nursing infants, including the potential for kernicterus in jaundiced infants, use during breastfeeding is not recommended. |
| 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. |
■ FDA Black Box Warning
None.
| Common Effects | GI upset |
| Serious Effects |
["Active peptic ulcer disease","Known hypersensitivity to sulfinpyrazone or sulfonamides","Severe 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"] |
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| 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. |