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Northyx (methimazole) Disease Interactions

There are 3 disease interactions with Northyx (methimazole):

Major

Thioamide derivatives (applies to Northyx) blood dyscrasias

Major Potential Hazard, Moderate plausibility. Applicable conditions: Neutropenia, Thrombocytopenia

The use of thioamide antithyroid agents may infrequently be associated with the development of blood dyscrasias, primarily agranulocytosis but also leukopenia, thrombocytopenia, and aplastic anemia. Most cases of agranulocytosis occur within the first two months of therapy, with incidence declining gradually thereafter. Patients older than 40 years of age and those receiving more than 40 mg/day of methimazole appear to be at substantially increased risk (a dosage association has not been reported for propylthiouracil). Therapy with thioamide derivatives should be administered cautiously in patients with or predisposed to blood dyscrasias and/or bone marrow depression. Clinical monitoring of hematopoietic function is recommended, with particular focus on leukocyte and differential counts. Because leukopenia (i.e. leukocyte count < 4000/mm3) may also occur in 10% of patients with untreated hyperthyroidism and is often associated with relative granulocytopenia, baseline count should be determined prior to initiating antithyroid medication. Patients should be instructed to immediately report during therapy any signs or symptoms suggestive of myelosuppression such as fever, sore throat, local infection, easy bruising, or bleeding. Cessation of antithyroid drug and institution of appropriate supportive measures are necessary if agranulocytosis or aplastic anemia develops.

References

  1. Shambaugh GE, 3d Khoury N, Zonschein J, Sizemore GW "Hypocalcemia accompanying agranulocytosis during propylthiouracil therapy." Ann Intern Med 91 (1979): 576-7
  2. "Product Information. Propylthiouracil (propylthiouracil)." Lederle Laboratories, Wayne, NJ.
  3. Valenta LJ, Elias AN, Weber DJ "Hyperthyroidism and propylthiouracil-induced agranulocytosis during chronic lithium carbonate therapy." Am J Psychiatry 138 (1981): 1605-7
  4. Hoffman DM, Burgess J, Hill P "Agranulocytosis and hepatic dysfunction following propylthiouracil treatment." Aust N Z J Med 24 (1994): 409-10
  5. Tajiri J, Noguchi S, Murakami T, Murakami N "Antithyroid drug-induced agranulocytosis. The usefulness of routine white blood cell count monitoring." Arch Intern Med 150 (1990): 621-4
  6. Cooper DS "Antithyroid drugs." N Engl J Med 311 (1984): 1353-62
  7. American Medical Association, Division of Drugs and Toxicology "Drug evaluations annual 1994." Chicago, IL: American Medical Association; (1994):
  8. Bishara J, Cux S, Pitlik S "Methimazole-induced aplastic anemia." Ann Pharmacother 30 (1996): 684
  9. "Product Information. Tapazole (methimazole)." King Pharmaceuticals Inc, Bristol, TN.
  10. Biswas N, Ahn YH, Goldman JM, Schwartz JM "Aplastic anemia associated with antithyroid drugs." Am J Med Sci 301 (1991): 190-4
View all 10 references
Major

Thioamide derivatives (applies to Northyx) hepatotoxicity

Major Potential Hazard, Low plausibility. Applicable conditions: Liver Disease, Alcoholism

The use of thioamide antithyroid agents has been associated with hepatotoxic effects, including transient elevations of serum transaminases and, rarely, cholestatic jaundice, fulminant hepatitis, hepatic necrosis, encephalopathy and death. Therapy with thioamide derivatives should be administered cautiously in patients with preexisting liver disease, a history of alcohol abuse, or hepatitis. Treatment should be discontinued if deterioration in liver function or other signs of hepatic injury occur. The jaundice associated with methimazole-induced hepatitis may persist for several weeks after withdrawal of the medication.

References

  1. American Medical Association, Division of Drugs and Toxicology "Drug evaluations annual 1994." Chicago, IL: American Medical Association; (1994):
  2. "Product Information. Propylthiouracil (propylthiouracil)." Lederle Laboratories, Wayne, NJ.
  3. Limaye A, Ruffolo PR "Propylthiouracil-induced fatal hepatic necrosis." Am J Gastroenterol 82 (1987): 152-4
  4. "Product Information. Tapazole (methimazole)." King Pharmaceuticals Inc, Bristol, TN.
  5. Hardee JT, Barnett AL, Thannoun A, Eghtesad B, Wheeler D, Jamal MM "Propylthiouracil-induced hepatotoxicity." West J Med 165 (1996): 144-7
  6. Hanson JS "Propylthiouracil and hepatitis. Two cases and a review of the literature." Arch Intern Med 144 (1984): 994-6
  7. Safani MM, Tatro DS, Rudd P "Fatal propylthiouracil-induced hepatitis ." Arch Intern Med 142 (1982): 838-9
  8. Deidiker R, Demello DE "Propylthiouracil-induced fulminant hepatitis: case report and review of the literature." Pediatr Pathol Lab Med 16 (1996): 845-52
  9. Liaw YF, Huang MJ, Fan KD, Li KL, Wu SS, Chen TJ "Hepatic injury during propylthiouracil therapy in patients with hyperthyroidism. A cohort study." Ann Intern Med 118 (1993): 424-8
  10. Ozenirler S, Tuncer C, Boztepe U, Akyol G, Alkim H, Cakir N, Kandilci U "Propylthiouracil-induced hepatic damage." Ann Pharmacother 30 (1996): 960-3
  11. Westphal SA "Hepatotoxicity from propylthiouracil." South Med J 87 (1994): 943-7
  12. Hoffman DM, Burgess J, Hill P "Agranulocytosis and hepatic dysfunction following propylthiouracil treatment." Aust N Z J Med 24 (1994): 409-10
  13. Seidman DS, Livni E, Ilie B, Blum I "Propylthiouracil-induced cholestatic jaundice." J Toxicol Clin Toxicol 24 (1986): 353-60
View all 13 references
Major

Thioamide derivatives (applies to Northyx) hypoprothombinemia

Major Potential Hazard, Low plausibility. Applicable conditions: Bleeding, Coagulation Defect, Thrombocytopathy, Vitamin K Deficiency

Thioamide antithyroid agents may interfere with the action of vitamin K and have been reported in isolated cases to induce hypoprothombinemia and bleeding. Myelosuppression rarely resulting in thrombocytopenia has also been reported. Therapy with thioamide derivatives should be administered cautiously in patients with significant active bleeding or a hemorrhagic diathesis, including hemostatic and/or coagulation defects associated with hemophilia, vitamin K deficiency, hypoprothombinemia, thrombocytopenia, thrombocytopathy, or severe hepatic impairment. Clinical monitoring of prothrombin time or INR is recommended.

References

  1. "Product Information. Tapazole (methimazole)." King Pharmaceuticals Inc, Bristol, TN.
  2. Sammon TJ, Peden VH, Witzleben C, King JP "Disseminated intravascular coagulation complicating propylthiouracil therapy. A case description of a 16-year-old girl." Clin Pediatr (Phila) 10 (1971): 739-42
  3. "Product Information. Propylthiouracil (propylthiouracil)." Lederle Laboratories, Wayne, NJ.

Northyx (methimazole) drug interactions

There are 53 drug interactions with Northyx (methimazole)

Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.