Interactions
Warfarin (Na) is known to interact with other drugs, the details of drug interactions is as follows:DrugDetailsSeverityOnsetManagementAceclofenacAceclofenac enhances the effect of oral anticoaggulants (e.g warfarin)Acetazolamide (Na)Acetazolamide potentiate effect of phenytoinAcrosoxacinAlcoholEnhanced anticoagulant effect with large amounts of alcohol. (Sequence important)AllopurinolAllopurinol may enhance the anticoagulant effect of Warfarin by inhibiting its metabolism.ModerateMonitor increased prothrombin times (PT)/therapeutic effects of Warfarin if allopurinol is initiated/dose increased, or decreased effects if Allopurinol is discontinued/dose decreased. Reductions in Warfarin dosage will likely be needed.AlteplaseAminoglutethimideAminoglutethimide may increase the metabolism, via CYP isoenzymes, of Warfarin.ModerateIncrease frequency of monitoring warfarin effects (eg, prothrombin time) with addition of aminoglutethimide. Monitor for decreased therapeutic effects of Warfarin if aminoglutethimide is initiated/dose increased, or increased effects if aminoglutethimide is discontinued/dose decreased. Amiodarone (HCl)Amiodarone may enhance the anticoagulant effect of Warfarin.MajorDelayedMonitor increased therapeutic effects of Warfarin if amiodarone is initiated/dose increased, or decreased effects if amiodarone is discontinued/dose decreased. An empiric warfarin dosage reduction of 30% to 50% at the initiation of amiodarone might be considered.Amitriptyline (HCl)Amitriptyline may enhance the anticoagulant effect of Warfarin. ModerateMonitor for increased prothrombin times (PT)/toxic effects of Warfarin if Amitriptyline is initiated/dose increased, or decreased effects if Amitriptyline is discontinued/dose decreased.Amlodipine (Besylate)AmoxicillinConcomitant use of amoxicillin and warfarin alters the INR.AmpicillinCommon experience in anticoaggulant clinics is that INR (International Normalized Ratio) can be altered by a course of broad-spectrum penicillins such as ampicillin.AprepitantDecrease in S(-) warfarin (a CYP2C9 substrate) trough concentration accompanied by a 14% decrease in the prothrombin time.In patients on chronic warfarin therapy, the prothrombin time (INR) should be closely monitored in the 2-week period, particularly at 7 to 10 days, following initiation of the 3-day regimen of aprepitant capsules with each chemotherapy cycle, or following administration of a single 40 mg dose of aprepitant capsules for the prevention of postoperative nausea and vomiting.AspirinAspirin may enhance the anticoagulant effect of Warfarin and thus increase the risk of bleeding by inhibiting platelet aggregation.MajorPatients receiving Warfarin should not take Aspirin on an as-needed basis. Nonacetylated salicylates might be safer than Aspirin. Acetaminophen ( 325 mg/day may require more frequent INR monitoring.AtorvastatinAtorvastatin may enhance the anticoagulant effect of Warfarin. Moderate (Sequence important)Patients who require concomitant thaerapy should be monitored for altered response whenever Warfarin is introduced or discontinued, or when its dosage is modified. Dosage adjustments of Warfarin may be needed.AzapropazoneAnticoagulant effect seriously enhanced by azapropazone.AVOID CONCOMITANT USE.AzathioprineAzathioprine may diminish the anticoagulant effect of Warfarin. ModerateMonitor for decreased therapeutic effects of Warfarin if Azathioprine is initiated/dose increased, or increased effects if Azathioprine is discontinued/dose decreased. An adjustment in Warfarin dosage may be needed. BendrofluazideBicalutamideBicalutamide possibly enhances anticoagulant effect of anticoagulants (e.g warfarin).CarbamazepineCarbamazepine may decrease the serum concentration of Warfarin. Patients on anticoaggulant therapy will suffer a serious bleeding disorder if carbamazepine is suddenly withdrawn.Moderate (Sequence important)Monitor for decreased therapeutic effects/prothrombin time of Warfarin if Carbamazepine is initiated/dose increased, or increased effects/prothrombin time if carbamazepine is discontinued/dose decreased. Patients stabilized on carbamazepine prior to warfarin initiation will not likely note this interaction.Carbenicillin (Na)Carbenicillin increases the risk of bleeding,prothrombin time and INR when administered with warfarin.ModerateINR should be check frequently and dose adjustment of warfarin is necessary.CarbimazoleCefamandole (Na)Cefamandole may enhance the anticoagulant effect of Warfarin. ModerateMonitor for increased evidence of bleeding if Cefamandole is used concomitant with Warfarin.Cephalosporins that have an NMTT side chain in their chemical structure may pose the greater risk of interaction. CefazolinCefazolin may enhance the anticoagulant effect of Warfarin.ModerateMonitor for increased evidence of bleeding if Cefazolin is used concomitant with Warfarin. Cephalosporins that have an NMTT side chain in their chemical structure may pose the greater risk of interaction. CefdinirCefiximeCefixime increases prothrombin time.CefoperazoneCefotetanCefotetan may enhance the anticoagulant effect of Warfarin. ModerateMonitor for increased evidence of bleeding if Cefotetan is used concomitant with Warfarin. Cephalosporins that have an NMTT side chain in their chemical structure may pose the greater risk of interaction. CeftibutenCelecoxibCetirizineIncreases inr and epistaxis,CNS depressants and anticholinergics may potentiate Chloral HydrateChlorambucilChloramphenicolChloramphenicol may enhance the anticoagulant effect of Warfarin.ModerateConcurrent therapy with Dicumarol and Chloramphenicol should probably be avoided. Little is known regarding the risks of concurrent therapy with Warfarin and Chloramphenicol. If these two agents are used together, monitor for increased effects of Warfarin (eg, prothrombin time, and signs and symptoms of bleeding) at initiation of therapy and if dose of Chloramphenicol is increased. If Chloramphenicol is discontinued or dose decreased, monitor for decreased effects of Warfarin. ChlorpropamideChlorpropamide either enhance or reduce the hypoprothrombinemic effect of warfarin by displacing it from plasma protein binding site. Warfarin also increase the blood level of chlorpropamide by inhibiting hepatic metabolism.ModerateProthrombin time, INR and blood sugar level should be monitor frequently. Patient should report the sign of bleeding to physician.CholestyramineCholestyramine reduces the anticoagulant effect of warfarin by decreasing absorption and increasing its elimination. ModerateClosely monitor for prothrombin time and INR . warfarin should administer at least one hour before or 4-6 hours after cholestyramine.Patient should report the sign of bleeding or clot to physician.Cimetidine (HCl)Cimetidine may enhance the anticoagulant effect of Warfarin. Moderate (Sequence important)If possible, use an alternative H2-antagonist. If Cimetidine must be used, monitor for increased therapeutic effects of the Warfarin when Cimetidine is initiated/dose increased, or decreased effects if Cimetidine is discontinued/dose decreased. CinoxacinCiprofibrateCiprofloxacinCiprofloxacin potentiate the hypoprothrombinemic effect of warfarin by inhibiting its metabolism and depleting certain clotting factors due to suppression of vitamin-k producing intestinal flora.MajorINR should be checked frequently and dose of warfarin should be adjusted whenever start or discontinue quinolone therapy. Patient should report any sign of bleeding to doctor.ClarithromycinClarithromycin enhances the hypoprothrombinemic effect of warfarin by inhibiting its metabolismMajorFrequently check INR Adjust the dose of warfarin accordingly especially when start or discontinue therapy with clarithromycin.Patient should report any sign of bleeding to physician.ClofibrateClofibrate may enhance the anticoagulant effect of Warfarin. MajorThe significance of this interaction may warrant a 25% to 33% reduction in the dosage of Warfarin if Clofibrate is to be started. Monitor for toxic effects of Warfarin if Clofibrate is initiated/dose increased, or decreased effects if Clofibrate is discontinued/dose decreased. Clomipramine (HCl)ClopidogrelClopidogrel does not appear to alter the pharmacodynamic effect(s) of Warfarin. Clopidogrel does not appear to affect serum concentration of Warfarin.N/ANo action required.ClozapineColestipol (HCl)Cop-FluampicilCo-TrimoxazoleCyclophosphamideCyclosporin AWarfarin and cyclosporin both either enhance or reduce the effects of one another.ModerateClosely monitor the prothrombin time . INR and cyclosporin blood concentration.Danazolco administration result in increase prothrombin time . danazol can significantly increase the hypoprothrombinemic action of oral anticoagulants by reducing the vitamin k available for metabolic competition with the anticoagulant.DesonideDesvenlafaxineAltered anticoagulant effects, including increased bleeding Patients receiving warfarin therapy should be carefully monitored when PRISTIQ is initiated or discontinuedcarefully monitored when PRISTIQ is initiated or discontinuedDexibuprofenThe effects of anticoagulants on bleeding time can be potentiated by NSAIDs. If concomitant treatment can not be avoided blood coagulation tests (INR, bleeding time) should be performed during the initiation of Dexibuprofen treatment and the dosage of the anticoagulant should be adjusted if necessary.DextropropoxypheneDiclofenac (Na)Diclofenac may enhance the anticoagulant effect of Warfarin. ModerateDelayedPatients receiving Warfarin should be instructed to not initiate Diclofenac without consulting his/her healthcare professional (nonacetylated salicylates might be safer alternatives). Acetaminophen is usually a good antipyretic and analgesic choice for patients taking Warfarin. Monitor for increased signs and symptoms of bleeding if Warfarin and Diclofenac are used concomitantly.DienoestrolDienosterol antagonize the effects of anticoagulants e.g warfarinDihydrocodeine (Tartrate)Di-IodohydroxyquinolineDipyridamoleDisodium EtidronateDisopyramideDisopyramide enhances the anticoagulant effect of warfarinMajorDelayedMonitor prothrombin time and INR of patientwhenever disopyramide added or discontinued.DisulfiramDisulfiram may increase the serum concentration of Warfarin. ModerateDelayedMonitor for increased therapeutic effects of Warfarin if Disulfiram is initiated/dose increased, or decreased effects if Disulfiram is discontinued/dose decreased. Dothiepin (HCl)Doxicycline HyclateDoxylamine SuccinateDoxylamine succinate may partially counteracts effects of warfarin.DutasterideLittle effect (EnoxaparinErythromycinErythromycin may decrease the metabolism, via CYP isoenzymes, of Warfarin. Prothrombin time and bleeding increasesModerate (Sequence important)Monitor for increased therapeutic effects of Warfarin if Erythromycin is initiated/dose increased, or decreased effects if Erythromycin is discontinued/dose decreased.EscitalopramUse with caution.EsmololEsomeprazoleEsomeprazole decrease the clearance of diazepam by inhibiting CYP450Ethacrynic AcidEthylestrenolEtodolacFelbamateFenbufenFenoprofenFenoprofen may enhance the anticoagulant effect of Warfarin. ModerateDelayedPatients receiving Warfarin should be instructed to not initiate Fenoprofen without consulting his/her healthcare professional (nonacetylated salicylates might be safer alternatives). Acetaminophen is usually a good antipyretic and analgesic choice for patients taking oral anticoagulants.Monitor for increased signs and symptoms of bleeding if Warfarin and Fenoprofen are used concomitantly. FluconazoleFluconazole may decrease the metabolism, via CYP isoenzymes, of Warfarin. ModerateDelayedMonitor for increased therapeutic/toxic effects of Warfarin if Fluconazole is initiated/dose increased, or decreased effects if Fluconazole is discontinued/dose decreased.Fluoxetine (HCl)FlutamideFluticasone PropionateFluvastatinFluvastatin may enhance the anticoagulant effect of Warfarin. Moderate (Sequence important)Monitor for increased effects of Warfarin if Fluvastatin is initiated/dose increased, or decreased effects if Fluvastatin is discontinued/dose decreased. Dosage adjustments of Warfarin may be needed.Fluvoxamine (Maleate)Fosinopril (Na)GemfibrozilGemfibrozil may enhance the anticoagulant effect of Warfarin. MajorThe significance of this interaction may warrant a 25% to 33% reduction in the dosage of Warfarin if Gemfibrozil is to be started. Monitor for toxic effects of Warfarin if Gemfibrozil is initiated/dose increased, or decreased effects if Gemfibrozil is discontinued/dose decreased. GlibenclamideGlucagon (HCl)GlucoseGriseofulvinGriseofulvin may increase the metabolism, via CYP isoenzymes, of Warfarin. ModerateMonitor for decreased therapeutic effects of Warfarin if Griseofulvin is initiated/dose increased, or increased effects if Griseofulvin is discontinued/dose decreased. HydrochlorothiazideHydroxocobalaminIfosfamideIfosfamide may enhance the anticoagulant effect of Warfarin. ModerateMonitor for increased INR/effects of Warfarin when ifosfamide is initiated/dose increased, and decreased INR/effects when ifosfamide is discontinued/dose decreased.Imatinib MesylateIndinavir (Sulphate)Influenza VaccineInterferon AlphaIpilimumabConcomitant use of anticoagulant and ipilimumab increases the risk of GI hemorrhage.Patient should be closely monitored when anticoaggulants are used with ipilimumabItraconazoleKetoconazoleKetoconazole may decrease the metabolism of Warfarin. ModerateConsider an alternative drug in order to avoid toxicity of Warfarin. Some combinations are specifically contraindicated by manufacturers. Suggested dosage adjustments are also offered by some manufacturers. Please review applicable package inserts. Monitor for increased effects of Warfarin if Ketoconazole is initiated/dose increased, and decreased effects if Ketoconazole is discontinued/dose decreased. Ketorolac (Tromethamine)Increased risk of haemorrhage with ketorolac.AVOID CONCOMITANT USE.LansoprazoleLevofloxacinLevofloxacin enhances the effect of oral anticoaggulants.Liothyronine (Na)LovastatinLovastatin increases the hypoprothrombinemic effect of warfarin.MajorDelayedClosely monitor the patient for altered anticoagulant effect. Patient should report the signs of bleeding to physician.MeclofenamateMeclofenamate sodium enhances the effect of warfarin. Therefore, when meclofenamate sodium is given to a patient receiving warfarin, the dosage of warfarin should be reduced to prevent excessive prolongation of the prothrombin time.When meclofenamate sodium is given to a patient receiving warfarin, the dosage of warfarin should be reduced to prevent excessive prolongation of the prothrombin time.Meclofenamic AcidMeclofenamic Acid may enhance the anticoagulant effect of Warfarin. ModerateDelayedPatients receiving Warfarin should be instructed to not initiate Meclofenamic Acid without consulting his/her healthcare professional (nonacetylated salicylates might be safer alternatives). Acetaminophen is usually a good antipyretic and analgesic choice for patients taking Warfarin. Monitor for increased signs and symptoms of bleeding if Warfarin and Meclofenamic acid are used concomitantly. MeprobamateMetacycline (HCl)MethyltestosteroneAndrogens and anabolic steroids may potentiate the hypoprothrombinemic response to oral anticoagulants and increase the risk of bleeding. The onset of interaction is generally observed within 2 to 3 days. The mechanism is unknown.MajorDuring concomitant therapy, the INR and/or PT should be monitored closely and anticoagulant dosage adjusted accordingly, particularly following initiation, discontinuation or change of dosage of the androgenic agent in patients who are stabilized on their anticoagulation regimen. Significant anticoagulant dose reductions may be required. Some experts recommend avoiding this combination altogether. Patients should be advised to promptly report any signs of bleeding to their physician, including pain, swelling, headache, dizziness, weakness, prolonged bleeding from cuts, increased menstrual flow, vaginal bleeding, nosebleeds, bleeding of gums from brushing, unusual bleeding or bruising, red or brown urine, or red or black stools. MetronidazoleMetronidazole increases the plasma concentration and thus hypoprothrombinemic effect of warfarin by inhibiting is metabolism, and hence increase prothrombin time of patients taking metronidazole.MajorFrequently checked INR and dose of warfarin should be adjusted accordingly. Patient should report any sign of bleeding to physician.MitotaneInfrequent reports of MITOTANE reducing the ANTICOAGULANT effect of WARFARIN SODIUM. ModerateModafinilConcomitant use may increase the toxicity of modafinil.MoxifloxacinMoxifloxacin enhances anticoaggulant effect of warfarin.NabumetoneThe effects of warfarin and Nabumetone on GI bleeding are synergistic, such that users of both drugs together have a risk of serious GI bleeding higher than users of either drug alone.Nadroparin (Ca)Risk of bleeding may be increased during concurrent therapy. Nadroparin is commonly continued during the initiation of warfarin therapy to assure anticoagulation and to protect against possible transient hypercoagulability.NaproxenNaproxen potentiate the hypoprothrombinemic effect of warfarin result in increased INR or prothrombin time thus increase risk of bleeding.ModerateDelayedINR should be checked frequently and dose of warfarin should be adjust accordingly, particularly following initiation or discontinuation of naproxen.NeomycinNilotinibwarfarin is metabolized by CYP2C9 and CYP3A4warfarin should be avoided with nilotinib if possibleNitazoxanideBoth warfarin and nitazoxanide metabolite (Tizoxanide) are highly protein bound and competetion for binding sites may occur.Caution should be used when administering nitazoxanide concurrently with other highly plasma protein-bound drugs with narrow therapeutic indices e.g. warfarinNorfloxacinNoscapineNoscapine may increase the effect of Warfarin (Na).Oligomeric ProcyanidinConcurrent use of high doses of OPCs with Warfarin (Na) might cause a risk of excessive bleeding. Olsalazine (Na)Omega-3-Acid Ethyl EstersConcurrent use may increase the risk of side effects.Omega-3-Marine TriglyceridesConcurrent use may increase the risk of bleeding.Omeprazoleomeperzole decrease the clearance of warfarinOrlistatThe blood thinning effect of warfarin (Coumadin) depends on the amount of vitamin K in the body, and vitamin K is one of the vitamins that binds to fat. Patients receiving warfarin who begin orlistat should have their blood clotting monitored closely because the orlistat may cause levels of vitamin K to decline.OxandroloneTheoretical potential for OXANDROLONE increasing the ANTICOAGULANT effect of WARFARIN SODIUM. MajorOxpentifyllineConcurrent use increases the anticoagulant effect.OxymetholoneLikely interaction of OXYMETHOLONE increasing the ANTICOAGULANT effect of WARFARIN SODIUM. MajorOxyphenbutazoneThese drugs should not be taken concurrently with out doctor and pharmacist approval.PantoprazolePantoprazole may increase the risk of side effects of Warfarin (Na).ParacetamolParacetamolParacetamol potentiate the hypoprothrombinemic effect of warfarinMinorMonitor signs of bleeding.ParoxetineParoxetin enhanced the risk of bleeding of warfarin by inhibiting release of serotonin from platelets which play an important role in hemostasis.ModerateClosely monitor the hemotological complication. Patient should report the signs of bleeding to physician.ParoxetinePentobarbitone (Na)PergolidePhenobarbitonePhenobarbitone may increase the metabolism, via CYP isoenzymes, of Warfarin. MajorDelayedMonitor for decreased therapeutic effects of Warfarin if Phenobarbitone is initiated/dose increased (anticoagulant dosage increases of 30% to 60% may be needed based on monitored PT), or increased effects if Phenobarbitone is discontinued/dose decreased. An increased frequency of PT monitoring should be considered for the period immediately following Phenobarbitone initiation/dosage changes. Phenylbutazone Phenytoin (Na)Phenytoin may enhance the anticoagulant effect of Warfarin. Warfarin may increase the serum concentration of Phenytoin. MajorDelayedConsideration should be given to using Warfarin instead of Dicumarol in phenytoin-treated patients, as Warfarin appears to exhibit a safer interaction profile. Monitor for increased effects of Warfarin (possibly transient), and significantly decreased effects of Dicumarol, if Phenytoin is initiated/dose increased, and the opposite effects if Phenytoin is discontinued/dose decreased. Monitor for increased serum concentrations/toxic effects of Phenytoin if Warfarin is initiated/dose increased, or decreased serum concentrations/effects if Warfarin is discontinued/dose decreased. These effects would manifest during the first 1-2 months of therapy, if at all. Piperacillin (Na)Penicillin potentiate the risk of bleeding by inhibiting platelet aggregation.ModerateClosely monitor for INR and adjust the dose of warfarin when either start or discontinue the therapy with penicillin. Patient should report any sign of bleeding to physician.PiracetamPiroxicamPiroxicam may enhance the anticoagulant effect of Warfarin.ModerateDelayedPatients receiving Warfarin should be instructed to not initiate Piroxicam without consulting his/her healthcare professional (nonacetylated salicylates might be safer alternatives). Acetaminophen is usually a good antipyretic and analgesic choice for patients taking Warfarin. Monitor for increased signs and symptoms of bleeding if Warfarin and Piroxicam are used concomitantly. Prasugrel HClCoadministration of Prasugrel and warfarin increases the risk of bleeding.Monitor bleeding time.Proguanil (HCl)Concurrent use may increase the anticoagulant effect of Warfarin (Na).Propafenone (HCl)PropoxyphenePropranolol (HCl)Quinalbarbitone (Na)QuinineQuinine may decrease the metabolism of Warfarin. ModerateMonitor for increased effects of the Warfarin if Quinine is initiated/dose increased, and decreased effects if Quinine is discontinued/dose decreased. RabeprazoleThere have been reports of increased INR and prothrombin time in patients receiving rabeprazole and warfarin concomitantly. Increases in INR and prothrombin time may lead to abnormal bleeding and even death.Raloxifene (HCl)Retinol (Vitamin A)Vitamin A inhibit the metabolism of warfarin.ModerateAvoid intake of vitamin A during therapy.Reviparin SodiumWarfarin (Na) may potentiate the action of Reviparin.RifabutinRifampicinSalicylamideThe risk of side effects, including the risk of bruising or bleeding, may be increased by concurrent use. SecnidazoleSerratiopeptidaseSerratiopeptidase intensify the effect of warfarin when administered concomitantly.MajorSilymarinSilymarin may interfere with Warfarin (Na) because both drugs are broken down by the same liver enzymes.SimvastatinSimvastatin may enhance the anticoagulant effect of Warfarin. Moderate (Sequence important)Monitor for increased effects of Warfarin if Simvastatin is initiated/dose increased, or decreased effects if Simvastatin is discontinued/dose decreased. Dosage adjustments of Warfarin may be needed.Sodium SalicylateSodium ValproateSpironolactoneSpironolactone may diminish the anticoagulant effect of Warfarin. ModerateNo action required.St.Johns Wort ExtractConcurrent use may decrease the effects of Warfarin (Na).StanozololSucralfateSulfadimidine Sulfadimidine inhibits the metabolism of Warfarin (Na) and enhances their action.SulfadoxineSulphadiazineSulphadiazine may decrease the metabolism of Warfarin.ModerateConsider an alternative drug in order to avoid toxicity of Warfarin. Some combinations are specifically contraindicated by manufacturers. Suggested dosage adjustments are also offered by some manufacturers. Please review applicable package inserts. Monitor for increased effects of Warfarin if Sulphadiazine is initiated/dose increased, and decreased effects if Sulphadiazine is discontinued/dose decreased. SulphamethizoleWarfarin (Na) may be displaced from protein binding sites or their metabolism may be inhibited by some sulfonamides, resulting in increased or prolonged effects or toxicity.Dosage adjustments may be necessary during and after sulfonamide therapySulphamethoxazoleSulphamethoxazole may decrease the metabolism of Warfarin. ModerateMonitor for increased effects of Warfarin if Sulphamethoxazole is initiated/dose increased, and decreased effects if Sulphamethoxazole is discontinued/dose decreased. SulphinpyrazoneSulphinpyrazone may decrease the metabolism of Warfarin.ModerateMonitor for increased effects of Warfarin if Sulphinpyrazone is initiated/dose increased, and decreased effects if Sulphinpyrazone is discontinued/dose decreased. Sultamicillin Penicillins can produce alterations in platelet aggregation and coagulation tests. These effects may be additive with anticoagulants. Tamoxifen (Citrate)Tamoxifen (Citrate)Tamoxifen increases the hypoprothrombinemic effect of warfarin by competing same metabolic pathways result in fatal hemorrhages.MajorMonitor for prolonged prothrombin time and excessive anticoagulation. Patient should notify the signs of excessive anticoagulation to physician.Tamsulosin HydrochlorideConcomitant use of these two drugs can potentially cause symptomatic hypotension. TenecteplaseConcurrent use is usually not recommended but may be required in some cases. If both medicines are prescribed together, change of dose may be required.TenoxicamAs tenoxicam is highly bound to serum albumin it can enhance the anticoagulant effect of warfarin and other anticoagulants. Close monitoring of the effects of anticoagulants and oral hypoglycaemic agents is advised, especially during the initial stages of treatment with tenoxicam.Testosterone (Esters)Testosterone may enhance the anticoagulant effect of Warfarin. ModerateRapidMonitor for increased therapeutic effects of Warfarin if Testosterone is initiated/dose increased, or decreased effects if Testosterone is discontinued/dose decreased. Significant reductions in Warfarin dosage may be needed during concomitant therapy. Thiopentone (Na)Thyroxine (Na)Tiaprofenic AcidWarfarin (Na) in combination with Tiaprofenic Acid can cause increased risk of bleeding. Tienilic AcidTocopherol (Vitamin E)Tocopherol (Vitamin E) prolong the prothrombin time of warfarin.Tramadol (HCl)anticoagulant effect of warfarin is increased.TrastuzumabTriclofos (Na)TrimethoprimTrimethoprim may decrease the metabolism of Warfarin.ModerateMonitor for increased effects of Warfarin if Trimethoprim is initiated/dose increased, and decreased effects if Trimethoprim is discontinued/dose decreased. Valproic AcidCoadministration of these drugs may lead to abnormal bleeding due to inability of blood to clot. VemurafenibVemurafenib increases the plasma concentration of Warfarin.VilazodoneDrug interefreing with hemostasis such as anticoagulant e.g warfarin may increase risk of bleedingcareful monitoring should be institutedVitamin KVitamin K antagonize the hypoprothrombinemic effect of warfarinModerateIntake of vitamin K through supplement or diet should not chage during warfarin therapy.Vortioxetineeither increases effects of other by anticoagulationmonitor closelyZafirlukastZafirlukast may decrease the metabolism, via CYP isoenzymes, of Warfarin.Moderate (Sequence important)Monitor for increased prothrombin time (PT)/effects of Warfarin if zafirlukast is initiated/dose increased, or decreased PT/effects if zafirlukast is discontinued/dose decreased. ZileutonZileuton may increase the serum concentration of Warfarin. ModerateMonitor for increased effects of Warfarin if Zileuton is initiated/dose increased and decreased effects if Zileuton is discontinued/dose decreased. These interactions are sometimes beneficial and sometimes may pose threats to life. Always consult your physician for the change of dose regimen or an alternative drug of choice that may strictly be required.