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propylthiouracil

Interactions

Anticoagulants/Antithyroid drugs

This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Moderate. These medicines may cause some risk when taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

When these two medicines are taken together, the antithyroid medication may cause your body to process vitamin-k slower. This may decrease the effects of the anticoagulant.

What might happen:

The effect of the blood-thinner may decrease.You may experience an increased chance for bleeding including bleeding from your gums, nosebleeds, unusual bruising, or dark stools if you stop taking the antithyroid drug.

What you should do about this interaction:

Ask your healthcare professionals (e.g. doctor or pharmacist) about taking these medicines together. If your doctor prescribes these medicines together, you may need to have your bleeding times checked more often. If you have any signs of bleeding, such as bleeding from your gums, nosebleeds, unusual bruising, or dark stools, contact your doctor right away.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.

References:

1.Greenstein RH. Hypoprothrombinemia due to propylthiouracil therapy. JAMA 1960 Jul 2;173(9):1014-5.

2.Naeye RL, Terrien CM. Hemorrhagic state after therapy with propylthiouracil. Am J Clin Pathol 1960 Sep;34(3):254-7.

3.Walters MB. The relationship between thyroid function and anticoagulant therapy. Am J Cardiol 1963 Jan;11:112-4.

4.Loeliger EA, van der Esch B, Mattern MJ, Hemker HC. The biological disappearance rate of prothrombin, factors VII, IX and X from plasma in hypothyoidism, hyperthyroidism, and during fever. Thrombos Diathes Haemorrh 1963;10:267-77.

5.Gilbert DK. Hypoprothrombinemia as a complication of propylthiouracil. JAMA 1964 Sep;189(11):855.

6.Rice AJ, McIntosh TJ, Fouts JR, Brunk SF, Wilson WR. Decreased sensitivity to warfarin in patients with myxedema. Am J Med Sci 1971 Oct;262(4):211-5.

7.Gotta AW, Sullivan CA, Seaman J, Jean-Gilles B. Prolonged intraoperative bleeding caused by propylthiouracil-induced hypoprothrombinemia. Anesthesiology 1972 Nov;37(5):562-3.

8.Vagenakis AG, Cote R, Miller ME, Braverman LE, Stohlman F Jr. Enhancement of warfarin-induced hypoprothrombinemia by thyrotoxicosis. Johns Hopkins Med J 1972 Jul;131(1):69-73.

9.Self T, Weisburst M, Wooten E, Straughn A, Oliver J. Warfarin-induced hypoprothrombinemia. Potentiation by hyperthyroidism. JAMA 1975 Mar 17; 231(11):1165-6.

10.Hansten PD. Drug interactions update. Oral anticoagulants and drugs which alter thyroid function. Drug Intell Clin Pharm 1980 May;14(5):331-4.

11.Costigan DC, Freedman MH, Ehrlich RM. Potentiation of oral anticoagulant effect by L-thyroxine. Clin Pediatr (Phila) 1984 Mar;23(3):172-4.

12.Akin F, Yaylali GF, Bastemir M, Yapar B. Effect of methimazole on warfarin anticoagulation in a case of Graves' disease. Blood Coagul Fibrinolysis 2008 Jan;19(1):89-91.

13.Squizzato A, Vitale J, Gerdes VE, Romualdi E, Buller HR, Ageno W. Recurrent deep venous thrombosis during optimal anticoagulation and overt hyperthyroidism: a case report. Blood Coagul Fibrinolysis 2007 Dec; 18(8):801-3.

14.Busenbark LA, Cushnie SA. Effect of Graves' disease and methimazole on warfarin anticoagulation. Ann Pharmacother 2006 Jun;40(6):1200-3.

Selected from data included with permission and copyrighted by First Databank, Inc. This copyrighted material has been downloaded from a licensed data provider and is not for distribution, expect as may be authorized by the applicable terms of use.

CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.

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