EXOGENOUS FACTORS:

Potential drug interactions with warfarin are listed below by drug class and by specific drugs.

Classes of Drugs
5-lipoxygenase Inhibitor Antiplatelet Drugs/Effects Leukotriene Receptor Antagonist
Adrenergic Stimulants, Central Antithyroid Drugs* Monoamine Oxidase Inhibitors
Alcohol Abuse Reduction Beta-Adrenergic Blockers Narcotics, prolonged
Preparations Cholelitholytic Agents Nonsteroidal Anti-Inflammatory
Analgesics Diabetes Agents, Oral Agents
Anesthetics, Inhalation Diuretics* Proton Pump Inhibitors
Antiandrogen Fungal Medications, Psychostimulants
Antiarrhythmics* Intravaginal, Systemic* Pyrazolones
Antibiotics* Gastric Acidity and Peptic Salicylates
Aminoglycosides (oral) Ulcer Agents* Selective Serotonin Reuptake
Cephalosporins, parenteral Gastrointestinal Inhibitors
Macrolides Prokinetic Agents Steroids, Adrenocortical*
Miscellaneous Ulcerative Colitis Agents Steroids, Anabolic (17-Alkyl
Penicillins, intravenous, high dose Gout Treatment Agents Testosterone Derivatives)
Quinolones (fluoroquinolones) Hemorrheologic Agents Thrombolytics
Sulfonamides, long acting Hepatotoxic Drugs Thyroid Drugs
Tetracyclines Hyperglycemic Agents Tuberculosis Agents*
Anticoagulants Hypertensive Emergency Agents Uricosuric Agents
Anticonvulsants* Hypnotics* Vaccines
Antidepressants* Hypolipidemics* Vitamins*
Antimalarial Agents Bile Acid-Binding Resins* 
Antineoplastics* Fibric Acid Derivitives 
Antiparasitic/Antimicrobials HMG-CoA Reductase Inhibitors* 
*
Increased and decreased PT/INR responses have been reported.
Specific Drugs Reported
acetaminophen fluconazole pantoprazole
alcohol* fluorouracil paroxetine
allopurinol fluoxetine penicillin G, intravenous
aminosalicylic acid flutamide pentoxifylline
amiodarone HCl fluvastatin phenylbutazone
argatroban fluvoxamine phenytoin*
aspirin gefitinib piperacillin
atenolol gemfibrozil piroxicam
atorvastatin* glucagon pravastatin*
azithromycin halothane prednisone*
bivalirudin heparin propafenone
capecitabine ibuprofen propoxyphene
cefamandole ifosfamide propranolol
cefazolin indomethacin propylthiouracil*
cefoperazone influenza virus vaccine quinidine
cefotetan itraconazole quinine
cefoxitin ketoprofen rabeprazole
ceftriaxone ketoralac ranitidine*
celecoxib lansoprazole rofecoxib
cerivastatin lepirudin sertaline
chenodiol levamisole simvastatin
chloramphenicol levofloxacin stanozolol
chloral hydrate* levothyroxine streptokinase
chlorpropamide liothyronine sulfamethizole
cholestyramine* lovastatin sulfamethoxazole
cimetidine mefenamic acid sulfinpyrazone
ciprofloxacin methimazole* sulfisoxazole
cisapride methyldopa sulindac
clarithromycin methylphenidate tamoxifen
clofibrate methylsalicylate ointment (topical) tetracycline
cyclophosphamide* metronidazole thyroid
danazol miconazole (intravaginal, oral, systemic) ticarcillin