Methimazole

Methimazole Brand Names- Northyx | Tapazole

What is Methimazole

Methimazole is an oral thioimidazole antithyroid agent.

Antithyroid agents are indicated for various hyperthyroid conditions including maintenance of a euthyroid state in patients with Graves’ disease until spontaneous remission occurs.

Methimazole is less likely to induce hepatotoxicity than propylthiouracil, especially in pediatric patients.

The drug is the preferred antithyroid agent for hyperthyroidism treatment when drug therapy must be used, except in the first trimester of pregnancy, where teratogenesis is a concern, or in cases of drug allergy or intolerance.

Methimazole was approved by the FDA in 1950.

Indications

  • Graves’ disease
  • hyperthyroidism
  • thyrotoxicosis

For the treatment of hyperthyroidism, including Graves’ disease or toxic multinodular goiter when surgery or radioactive iodine therapy (RAI) is not appropriate, or for symptomatic treatment in preparation for thyroidectomy or RAI

Side Effects

  1. agranulocytosis
  2. alopecia
  3. anorexia
  4. aplastic anemia
  5. arthralgia
  6. bleeding
  7. drowsiness
  8. dysgeusia
  9. edema
  10. elevated hepatic enzymes
  11. exfoliative dermatitis
  12. fever
  13. headache
  14. hepatic encephalopathy
  15. hepatic necrosis
  16. hepatitis
  17. hypoglycemia
  18. hypoprothrombinemia
  19. hypothyroidism
  20. jaundice
  21. leukopenia
  22. lupus-like symptoms
  23. lymphadenopathy
  24. myalgia
  25. nausea
  26. nephrotic syndrome
  27. neuritis
  28. neutropenia
  29. pancytopenia
  30. paresthesias
  31. periarteritis
  32. peripheral neuropathy
  33. pruritus
  34. rash
  35. sialadenitis
  36. skin hyperpigmentation
  37. teratogenesis
  38. thrombocytopenia
  39. urticaria
  40. vasculitis
  41. vertigo
  42. vomiting

Monitoring Parameters

  • CBC with differential
  • LFTs
  • thyroid function tests (TFTs)

Contraindications

  • agranulocytosis
  • aplastic anemia
  • bone marrow suppression
  • breast-feeding
  • geriatric
  • hepatic disease
  • hepatitis
  • hepatotoxicity
  • jaundice
  • leukopenia
  • neutropenia
  • pregnancy
  • serious rash
  • thrombocytopenia
  • vasculitis

Interactions

  • Acebutolol
  • Amiodarone
  • Atenolol
  • Atenolol; Chlorthalidone
  • Bendroflumethiazide; Nadolol
  • Beta-blockers
  • Betaxolol
  • Bisoprolol
  • Bisoprolol; Hydrochlorothiazide, HCTZ
  • Brimonidine; Timolol
  • Carteolol
  • Carvedilol
  • Deferiprone
  • Digoxin
  • Dorzolamide; Timolol
  • Esmolol
  • Hydrochlorothiazide, HCTZ; Metoprolol
  • Hydrochlorothiazide, HCTZ; Propranolol
  • Iodine; Potassium Iodide, KI
  • Iodoquinol
  • Labetalol
  • Levobetaxolol
  • Levobunolol
  • Macimorelin
  • Metoprolol
  • Nadolol
  • Nebivolol
  • Nebivolol; Valsartan
  • Penbutolol
  • Pindolol
  • Potassium Iodide, KI
  • Propranolol
  • Sodium Iodide
  • Sotalol
  • Theophylline, Aminophylline
  • Thyroid hormones
  • Timolol
  • Warfarin
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