Oral anticoagulants cholestyramine

When administered with cholestyramine or colestipol there is a decreased absorption of the oral thyroid preparations. These drugs should not be administered within 4 of 6 hours of the thyroid hormones. When administered with the oral anticoagulants there is an increased risk of bleeding. It may be advantageous to decrease the dosage of the anticoagulant when a thyroid preparation is prescribed. There is a decreased effectiveness of the digitalis preparation if taken with a thyroid preparation. 

Oral anticoagulants Insulin or oral hypoglycemics Cholestyramine Estrogen, oral contraceptives... 

Uses Acute chronic gout Action X Renal tubular absorption of uric acid Dose 100-200 mg PO bid for 1 wk, T PRN to maint of 200—400 mg bid max 800 mg/d take w/ food or antacids plenty of fluids avoid salicylates Caution [C (D if near term), /-] Contra Renal impair, avoid salicylates peptic ulcer blood dyscrasias, near term PRG, allergy Disp Tabs, caps SE N/V, stomach pain, urolithiasis, leukopenia Interactions T Effects OF oral anticoagulants, oral hypoglycemics, MTX X effects W/ ASA, cholestyramine, niacin, salicylates, EtOH X effects OF acetaminophen, theophylline, verapamil EMS T Effects of anticoagulants and oral hypoglycemic X effects of verapamil OD May cause N/V, loss of coordination, dyspnea, Szs symptomatic and supportive... 

The bile acids sequestrants, particularly cholestyramine, can decrease tlie absorption of numerous dru. For tliis reason, tlie bile acid sequestrants should be administered alone and otlier dru given at least 1 hour before or 4 hours after administration of the bile acid sequestrants. There is an increased risk of bleeding when tlie bile acid sequestrants are administered with oral anticoagulants. The dosage of the antico ulant is usually decreased. The bile acid sequestrants may bind with digoxin, tliiazide diuretics, penicillin, propranolol, tetracyclines, folic acid, and tlie thyroid hormone, resulting in decreased effects of th e dru. ... 

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). 

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