Northyx

Dosage Forms & Strengths

tablet

• 5mg
• 10mg

Hyperthyroidism

Mild: 15 mg/day PO divided q8hr initially

Moderate: 30-40 mg/day PO divided q8hr initially

Severe: 60 mg/day PO divided q8hr initially

Maintenance: 5-30 mg/day PO divided q8hr

Graves Disease

10-20 mg/day PO once; after euthyroidism is achieved, reduce dosage by 50% and administer for 12-18 months; may subsequently taper or discontinue if TSH levels are normal

Thyrotoxicosis (Off-label)

15-20 mg PO q4hr during first day as adjunct to other agents; reduce frequency to qDay or q12hr once patient is stable

Orphan Designations

Brain metastases: Orphan designation (plus liothyronine) for brain metastases in patients with primary lung cancer

Glioblastoma mutiforme: Orphan designation (plus liothyronine) for treatment of glioblastoma multiforme

Sponsor

• Musli Thyropeutics Ltd; 6 Hagefen Street, P. O. Box 529; Zur Moshe, Israel

Dosage Forms & Strengths

tablet

• 5mg
• 10mg

Hyperthyroidism

Initial: 0.5-0.7 mg/kg/day PO qDay or divided q8hr 

Maintenance: 0.2 mg/kg/day PO qDay or divided q8hr

Not to exceed 30 mg/day

Graves Disease

0.2-0.5 mg/kg/day PO; after euthyroidism is achieved, reduce dosage by 50% and administer for 1-2 years  

Thyrotoxicosis (Off-label)

0.5-1 mg/kg/day PO divided q8hr; adjust subsequent doses and duration of treatment based on patient response

Frequency Not Defined

Agranulocytosis

Alopecia

Aplastic anemia

Dermatologic reactions (eg, rash, pruritus, skin pigmentation)

Hepatotoxicity

Leukocytoclastic vasculitis

Neuritis

Polyarthritis

Pruritus

Salivary gland swelling

Skin pigmentation

Thrombocytopenia

Urticaria

Vertigo

The initial adult dose of methimazole is:

• 15 mg/day for mild hyperthyroidism
• 30-40 mg/day for moderately severe hyperthyroidism
• 60 mg/day for severe hyperthyroidism

The daily dose is divided into three doses administered every 8 hours.

The maintenance dose is 5-15 mg/day.

The usual initial children's dose is 0.4 mg/kg given in 3 divided doses administered 8 hours apart, and the maintenance dose is half the initial dose.

: Warfarin (Coumadin) works by reducing the activity of vitamin K and therefore the formation of vitamin K dependent clotting factors. Methimazole may increase the activity of warfarin by further reducing the activity of vitamin K in the body.

Hyperthyroidism increases elimination of beta blockers. Correcting hyperthyroidism will cause less elimination of beta blockers. Therefore, the dose of beta blockers may require reduction when hyperthyroidism is corrected. A similar reaction may also occur with digoxin (Lanoxin) and theophylline (Respbid, Slo-Bid, Theo-24, Theolair).

Serious side effects have been reported with methimazole. See the "Drug Precautions" section.

Common side effects of methimazole include the following:

• rash
• nausea
• vomiting
• indigestion
• joint pain
• tingling sensation
• loss of taste
• hair loss
• muscle pain
• headache
• vertigo
• itchiness
• salivary gland inflammation
• lymph node inflammation

This is not a complete list of methimazole side effects. Ask your doctor or pharmacist for more information.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you take:

• a beta blocker such as acebutolol (Sectral), atenolol (Tenormin), betaxolol (Kerlone), bisoprolol (Zebeta), carvedilol (Coreg), esmolol (Brevibloc), labetalol (Trandate), metoprolol (Lopressor, Toprol XL), nadolol (Corgard), nebivolol (Bystolic), penbutolol (Levatol), propranolol (Inderal), sotalol (Betapace), timolol (Blocadren)
• digoxin (Digitek, Lanoxin)
• theophylline (Theo-24,  Theobid, Theo-Dur, Theolair, Elixophyllin, Elixophylline, Quibron-T, Uniphyl)
• warfarin (Coumadin, Jantoven)

This is not a complete list of methimazole drug interactions. Ask your doctor or pharmacist for more information.

Take methimazole exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The methimazole dose your doctor recommends will be based on the following:

• the condition being treated
• other medical conditions you have
• other medications you are taking
• how you respond to this medication
• your weight (children)

The recommended starting daily dosage is 15 mg for mild hyperthyroidism, 30 to 40 mg for moderately severe hyperthyroidism, and 60 mg for severe hyperthyroidism, divided into 3 doses at 8-hour intervals.

The maintenance dosage is 5 to 15 mg daily.

If you take too much methimazole, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.