Drug Facts
Composition & Profile
Identifiers & Packaging
HOW SUPPLIED Methimazole Tablets, USP, for oral administration, are available as 5 mg White, round scored tablet, de-bossed with "CE" over "36" on one side and functional score on the other side and supplied as: NDC 62135-205-30 bottles of 30 NDC 62135-205-90 bottles of 90 NDC 62135-205-01 bottles of 100 NDC 62135-205-18 bottles of 180 NDC 62135-205-05 bottles of 500 10 mg White, round scored tablet, de-bossed with "CE" over "37" on one side and functional score on the other side and supplied as: NDC 62135-206-30 bottles of 30 NDC 62135-206-90 bottles of 90 NDC 62135-206-01 bottles of 100 NDC 62135-206-18 bottles of 180; PACKAGE LABEL.PRINCIPAL DISPLAY PANEL Methimazole Tablets, USP 5 mg - NDC 62135-205-30 - 30 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-90 - 90 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-01 - 100 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-18 - 180 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-05 - 500 Tablets Label Methimazole Tablets, USP 10 mg - NDC 62135-206-30 - 30 Tablets Label Methimazole Tablets, USP 10 mg - NDC 62135-206-90 - 90 Tablets Label Methimazole Tablets, USP 10 mg - NDC 62135-206-01 - 100 Tablets Label Methimazole Tablets, USP 10 mg - NDC 62135-206-18 - 180 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-30 - 30 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-90 - 90 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-01 - 100 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-18 - 180 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-18 - 500 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-30 - 30 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-90 - 90 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-01 - 100 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-18 - 180 Tablets Label
- HOW SUPPLIED Methimazole Tablets, USP, for oral administration, are available as 5 mg White, round scored tablet, de-bossed with "CE" over "36" on one side and functional score on the other side and supplied as: NDC 62135-205-30 bottles of 30 NDC 62135-205-90 bottles of 90 NDC 62135-205-01 bottles of 100 NDC 62135-205-18 bottles of 180 NDC 62135-205-05 bottles of 500 10 mg White, round scored tablet, de-bossed with "CE" over "37" on one side and functional score on the other side and supplied as: NDC 62135-206-30 bottles of 30 NDC 62135-206-90 bottles of 90 NDC 62135-206-01 bottles of 100 NDC 62135-206-18 bottles of 180
- PACKAGE LABEL.PRINCIPAL DISPLAY PANEL Methimazole Tablets, USP 5 mg - NDC 62135-205-30 - 30 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-90 - 90 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-01 - 100 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-18 - 180 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-05 - 500 Tablets Label Methimazole Tablets, USP 10 mg - NDC 62135-206-30 - 30 Tablets Label Methimazole Tablets, USP 10 mg - NDC 62135-206-90 - 90 Tablets Label Methimazole Tablets, USP 10 mg - NDC 62135-206-01 - 100 Tablets Label Methimazole Tablets, USP 10 mg - NDC 62135-206-18 - 180 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-30 - 30 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-90 - 90 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-01 - 100 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-18 - 180 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-18 - 500 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-30 - 30 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-90 - 90 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-01 - 100 Tablets Label Methimazole Tablets, USP 5 mg - NDC 62135-205-18 - 180 Tablets Label
Overview
Methimazole, USP (1-methylimidazole-2-thiol) is a white, crystalline substance that is freely soluble in water. It differs chemically from the drugs of the thiouracil series primarily because it has a 5- instead of a 6-membered ring. Each tablet contains 5 mg or 10 mg (43.8 mcmol or 87.6 mcmol) methimazole USP, an orally administered antithyroid drug. Each tablet also contains anhydrous lactose, colloidal silicon dioxide, lactose monohydrate, magnesium stearate, pregelatinized starch (corn) and talc. The molecular weight is 114.16, and the molecular formula is C 4 H 6 N 2 S. The structural formula is as follows: image description
Indications & Usage
Methimazole tablets, USP are indicated: In patients with Graves’ disease with hyperthyroidism or toxic multinodular goiter for whom surgery or radioactive iodine therapy is not an appropriate treatment option. To ameliorate symptoms of hyperthyroidism in preparation for thyroidectomy or radioactive iodine therapy.
Dosage & Administration
Methimazole tablets, USP are administered orally. The total daily dosage is usually given in 3 divided doses at approximately 8-hour intervals. Adult The initial daily dosage is 15 mg for mild hyperthyroidism, 30 mg 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 mg to 15 mg daily. Pediatric Initially, the daily dosage is 0.4 mg/kg of body weight divided into 3 doses and given at 8-hour intervals. The maintenance dosage is approximately 1/2 of the initial dose.
Warnings & Precautions
WARNINGS First Trimester Use of Methimazole and Congenital Malformations Methimazole crosses the placental membranes and can cause fetal harm, when administered in the first trimester of pregnancy. Rare instances of congenital defects, including aplasia cutis, craniofacial malformations (facial dysmorphism; choanal atresia) gastrointestinal malformations (esophageal atresia with or without tracheoesophageal fistula) omphalocele and abnormalities of the omphalomesenteric duct have occurred in infants born to mothers who received methimazole in the first trimester of pregnancy. If methimazole is used during pregnancy or if the patient becomes pregnant while taking this drug, the patient should be warned of the potential hazard to the fetus. Because of the risk for congenital malformations associated with use of methimazole in the first trimester of pregnancy it may be appropriate to use other agents in pregnant women requiring treatment for hyperthyroidism. If methimazole is used, the lowest possible dose to control the maternal disease should be given. Agranulocytosis Agranulocytosis is potentially a life-threatening adverse reaction of methimazole therapy. Patients should be instructed to immediately report to their physicians any symptoms suggestive of agranulocytosis, such as fever or sore throat. Leukopenia, thrombocytopenia, and aplastic anemia (pancytopenia) may also occur. The drug should be discontinued in the presence of agranulocytosis or aplastic anemia (pancytopenia), and the patient’s bone marrow indices should be monitored. Liver Toxicity Although there have been reports of hepatotoxicity (including acute liver failure) associated with methimazole, the risk of hepatotoxicity appears to be less with methimazole than with propylthiouracil, especially in the pediatric population. Symptoms suggestive of hepatic dysfunction (anorexia, pruritis, right upper quadrant pain, etc.) should prompt evaluation of liver function (bilirubin, alkaline phosphatase) and hepatocellular integrity (ALT, AST). Drug treatment should be discontinued promptly in the event of clinically significant evidence of liver abnormality including hepatic transaminase values exceeding 3 times the upper limit of normal. Hypothyroidism Methimazole can cause hypothyroidism necessitating routine monitoring of TSH and free T4 levels with adjustments in dosing to maintain a euthyroid state. Because the drug readily crosses placental membranes, methimazole can cause fetal goiter and cretinism when administered to a pregnant woman. For this reason, it is important that a sufficient, but not excessive, dose be given during pregnancy (see PRECAUTIONS, Pregnancy ). Vasculitis Cases of vasculitis resulting in severe complications have been reported in patients receiving Methimazole therapy. These cases of vasculitis include: leukocytoclastic cutaneous vasculitis, acute kidney injury and glomerulonephritis, alveolar/pulmonary hemorrhage, CNS vasculitis, and neuropathy. Most cases were associated with anti-neutrophilic cytoplasmic antibodies (ANCA)-positive vasculitis. In some cases, vasculitis resolved/improved with drug discontinuation; however, more severe cases required treatment with additional measures including corticosteroids, immunosuppressant therapy, and plasmapheresis. If vasculitis is suspected, discontinue therapy and initiate appropriate intervention.
Contraindications
Methimazole is contraindicated in the presence of hypersensitivity to the drug or any of the other product components.
Adverse Reactions
Major adverse reactions (which occur with much less frequency than the minor adverse reactions) include inhibition of myelopoieses (agranulocytosis, granulocytopenia, thrombocytopenia, and aplastic anemia), drug fever, a lupus-like syndrome, insulin autoimmune syndrome (which can result in hypoglycemic coma), hepatitis (jaundice may persist for several weeks after discontinuation of the drug), periarteritis, and hypoprothrombinemia. Nephritis occurs very rarely. Minor adverse reactions include skin rash, urticaria, nausea, vomiting, epigastric distress, arthralgia, paresthesia, loss of taste, abnormal loss of hair, myalgia, headache, pruritus, drowsiness, neuritis, edema, vertigo, skin pigmentation, jaundice, sialadenopathy, and lymphadenopathy. There are reports of a vasculitis, often associated with the presence of anti-neutrophilic cytoplasmic antibodies (ANCA), resulting in severe complications (see WARNINGS ).
Storage & Handling
STORAGE Store at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature]. Dispense contents in a tight, light-resistant container as defined in the USP with a child-resistant closure, as required. KEEP TIGHTLY CLOSED. KEEP THIS AND ALL MEDICATION OUT OF THE REACH OF CHILDREN. WARNING – This drug may cause toxic reaction. If such reactions occur, discontinue the drug. Constant supervision of patient is essential. To report SUSPECTED ADVERSE REACTIONS, contact Chartwell RX, LLC. at 845-232-1683 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. Manufactured by: Chartwell Pharmaceuticals, LLC. Congers, NY 10920 Manufactured for: Chartwell RX, LLC. Congers, NY 10920 L70634 Rev: 10/2021
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