Warfarin with cholestyramine

Jahnchen E, Meinertz T, Gilfrich HJ, Kersting F, Groth U. Enhanced elimination of warfarin during treatment with cholestyramine. Br J Clin Pharmacol 1978 5(5) 437M0. 

Treatment with cholestyramine decreases the anticoagulant effects of warfarin compound reduces the need for platelet transfusions in patients undergoing cancer chemotherapy. 

Drug interactions anticonvulsants (phenytoin, barbiturates, carbamazepine) increase the risk of hepatotoxicity by increasing conversion of acetaminophen to toxic metabolites. Isoniazide also increases risk of acetaminophen hepatotoxicity. Acetaminophen may enhance the anticoagulant effect of warfarin with daily doses > 1.3 g for > 1 week. Phenothiazines may increase risk of severe hypothermia with acetaminophen. Cholestyramine resin may decrease the absorption of acetaminophen. 

Drugs that may interact with raloxifene include ampicillin and cholestyramine. Raloxifene may affect warfarin. 

The principal precaution with use of the bile acid resins is the possibility of impaired absorption of other drugs given orally at the same time. Cholestyramine and colestipol can bind many other drugs, such as digitoxin, phenobarbital, chlorothiazide, and warfarin, and delay or prevent their absorption. For this reason, other drugs should always be taken at least 1 hour before or 4 to 6 hours after the resin. The resins can also decease absorption of fat-soluble vitamins. 

Warfarin antagonists include vitamin K, barbiturates, glutethimide. rifampin, and cholestyramine. Warfarin potentiators include phenylbutazone. oxyphenbutazone, anabolic steroids, clofibrate, aspirin, hepatotoxins, disnlfirain, and metronidazole. In patients undergoing anticoagulation therapy with warfann, it has been found that cimetidine (used in therapy of duodenal ulcer) may increase anticoagulant blood levels and consequently prolong the prothrombin time. 

Cholestyramine and Colestipol. Other interactions involving complexation might be anticipated when cholestyramine (e.g., Questran) and colestipol (Coles-tid) are used. These resinous materials, which are not absorbed from the GI tract, bind with bile acids and prevent their reabsorption. In addition, cholestyramine and colestipol can bind with drugs (e.g., digoxin and warfarin) that are present in the GI tract. To minimize the possibility of an interaction, the interval between the administration of cholestyramine or colestipol and another drug should be as long as possible. 

Clinically important, potentially hazardous interactions with acenocoumarol, anagrelide, anticoagulants, bismuth, boswellia, calcium hydroxylapatite, capsicum, cholestyramine, desvenlafaxine, devil s claw, dexamethasone, dexibuprofen, dicumarol, etodolac, evening primrose, flunisolide, ginkgo biloba, ginseng, heparin, ibuprofen, indomethacin, ketoprofen, ketorolac, lumiracoxib, methotrexate, methylprednisolone, nilutamide, NSAIDs, phellodendron, prednisone, resveratrol, reteplase, rivaroxaban, sermorelin, sulfites, tirofiban, triamcinolone, urokinase, valdecoxib, valproic acid, verapamil, warfarin... 

Clinically important, potentially hazardous interactions with amiloride, aminoglycosides, amphotericin B, ampicillin, anisindione, anticoagulants, armodafinil, atorvastatin, azathioprine, azithromycin, bacampicillin, basiliximab, bezafibrate, bosentan, bupropion, carbenicillin, caspofungin, cholestyramine, clarithromycin, cloxacillin, co-trimoxazole, corticosteroids, cyclophosphamide, daclizumab, danazol, dicloxacillin, dicumarol, digoxin, diltiazem, disulfiram, echinacea, erythromycin, ethotoin, etoposide, ezetimibe, flunisolide, fluoxymesterone, fluvastatin, foscarnet, fosphenytoin, gemfibrozil, hemophilus B vaccine, HMG-CoA reductase inhibitors, imatinib, imipenem/cilastatin, influenza vaccines, ketoconazole, lanreotide, lopinavir, lovastatin, mephenytoin, methicillin, methoxsalen, methylphenidate, methylprednisolone, methyltestosterone, mezlocillin, mizolastine, mycophenolate, nafcillin, nisoldipine, NSAIDs, orlistat, oxacillin, penicillins, phellodendron, phenytoin, pravastatin, prednisolone, prednisone, pristinamycin, ranolazine, red rice yeast, rifabutin, rifampin, rifapentine, ritonavir, rosuvastatin, simvastatin, sirolimus, spironolactone, St John s wort, sulfacetamide, sulfadiazine, sulfamethoxazole, sulfisoxazole, sulfonamides, tacrolimus, telithromycin, tenoxicam, testosterone, ticarcillin, tolvaptan, trabectedin, triamterene, troleandomycin, ursodeoxycholic acid, vaccines, vecuronium, warfarin, zofenopril... 

Cholestyramine interferes with the oral absorption of many drugs (including wrirfarin), resulting in decreased effectiveness. Aspirin and thyroid hormones enhance the action of warfarin via pharmacodynamic mechanisms. Increased anticoagulant effects with cimetidine or quini-dine result from the inhibition of metabolism of warfarin. The answer is (B). 

Warfarin reduces the synthesis of prothrombin and several other clotting factors. Carbamazepine and rifampin interfere with this action by increasing the metabolism of warfarin. Cholestyramine decreases the oral absorption of warfarin and other acidic drugs. Vitamin K is the antidote to excessive effects of warfarin. Antiplatelet drugs such as naproxen enhance the anticoagulant effects of warfarin. The answer is (C). 

Meloxicam has been shown to have interactions with the following common medications ACE inhibitors, aspirin, cholestyramine, cimetidine, digoxin, furo-semide, hthium, methotrexate, warfarin [ 1 ]. 

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