33 phenylbutazone, azapropazon and oxyfenbutazone insulin and oral antidiabetic products metformin salicylates and p-amino-salicylic acid anabolic steroids and male sex hormones chloramphenicol coumarin anticoagulants fenfluramine fibrates ACE inhibitors fluoxetine allopurinol sympatholytics cyclo-, tro-and iphosphamides sulphinpyrazone certain long-acting sulphonamides tetracyclines MAO-inhibitors quinolone antibiotics probenecid miconazol pentoxyfylline (high dose parenteral) tritoqualine fluconazole