<p>Decreased therapeutic effect when given with drugs that increase uric acid concentration (e.g. diuretics, pyrazinamide). May potentiate the action of coumarin anticoagulants (e.g. warfarin, acenocoumarol), hypoglycaemic agents and sulfonamides. May decrease plasma levels of theophylline. May increase plasma levels of penicillins and phenytoin. Increased risk of haemorrhage with substances affecting homeostasis (e.g. non-steroidal antirheumatic drugs). Probenecid may inhibit renal tubular secretion of sulfinpyrazone.</p>