Sulfinpyrazone (Anturane), another uricosuric agent, is chemically related to the antiinflammatory and urico-
suric compound phenylbutazone. However, it lacks the antiinflammatory, analgesic, and sodium-retaining properties of phenylbutazone and possesses a number of undesirable side effects that limit its therapeutic usefulness. The mechanism of sulfinpyrazone's uricosuric activity is similar to that of probenecid.
Sulfinpyrazone is readily absorbed after oral administration, with peak blood levels reached 1 to 2 hours after ingestion. It is more highly bound to plasma protein (98-99%) than is probenecid (84-94%) and is a more potent uricosuric agent. Most of the drug (90%) is eliminated through active proximal tubular secretion of the intact parent compound. Sulfinpyrazone also undergoes p-hydroxylation to form a uricosuric metabolite, the formation of which undoubtedly contributes to the drug's prolonged activity (about 10 hours) and potency relative to probenecid. In contrast to probenecid, the rate of excretion of sulfinpyrazone is not enhanced by alkalinization of the urine, since the drug is largely ionized at all urinary pH ranges and therefore not a candidate for passive back-diffusion.
Sulfinpyrazone, although less effective than allop-urinol in reducing serum uric acid levels, remains useful for the prevention or reduction of the joint changes and tophus deposition that would otherwise occur in chronic gout; it has no antiinflammatory properties. During the initial period of sulfinpyrazone use, acute attacks of gout may increase in frequency and severity. It is recommended, therefore, that either colchicine or a nonsteroidal antiinflammatory agent be coadministered during early sulfinpyrazone therapy.
Abdominal pain, nausea, and possible reactivation of peptic ulcer have been reported. The drug should be used with caution in patients with compromised renal function, and adequate fluid intake should always accompany sulfinpyrazone administration to minimize the possibility of renal calculus formation.
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