Sulphinpyrazone prevents in vivo the inhibitory effect of aspirin on rat platelet cyclo-oxygenase activity

Grazyna Rajtar, Chiara Cerletti, Manuela Livio, Giovanni de Gaetano

Research output: Contribution to journalArticlepeer-review


Sulphinpyrazone reportedly inhibits in vitro platelet cyclo-oxygenase activity. This study shows that Sulphinpyrazone administration (200 mg/kg) to rats was followed by long lasting inhibition of platelet cyclo-oxygenase, as measured by malondialdehyde generation by sodium arachidonate. The inhibition was apparently competitive and could in fact be ascribed to supposed metabolites of the drug. When given 30min-6 hours before aspirin (5-25mg/kg), Sulphinpyrazone and to a considerable extent its metabolites significantly prevented permanent inhibition of platelet cyclo-oxygenase activity normally produced in vivo by aspirin. Sulphinpyrazone at 100 mg/kg was unable by itself to modify platelet malondialdehyde or thromboxane B2 generation, yet if effectively interfered with aspirin activity. This suggests that Sulphinpyrazone and its metabolites may interact with a binding site on cyclo-oxygenase not directly involved with the enzyme activity. Interaction of aspirin with this binding site would be a prerequisite for its inhibitory effect on the enzyme active site. The clinical implications of this study include a reappraisal of the pharmacological basis for the association of Sulphinpyrazone and aspirin in thrombosis prevention trials.

Original languageEnglish
Pages (from-to)2773-2776
Number of pages4
JournalBiochemical Pharmacology
Issue number20
Publication statusPublished - Oct 15 1981

ASJC Scopus subject areas

  • Pharmacology


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