Antithyroid medications. (Medication Update).Mode of Action Propylthiouracil and methimazole inhibit thyroid hormone Thyroid hormone Any of the chemical messengers produced by the thyroid gland, including thyrocalcitonin, a polypeptide, and thyroxine and triiodothyronine, which are iodinated thyronines. See Hormone, Thyrocalcitonin, Thyroid gland, Thyroxine production. Sodium iodide I"' is taken up by the thyroid and protein bound there, where it irradiates the thyroid with beta and gamma emissions. Contraindications Nursing mothers. Known hypersensitivity hypersensitivity, heightened response in a body tissue to an antigen or foreign substance. The body normally responds to an antigen by producing specific antibodies against it. The antibodies impart immunity for any later exposure to that antigen. to the agent or components of their formulation. Pregnancy category: D (propyithiouracil and methimazole). Pregnancy category X: (sodium iodide I (131). Adverse Efftcts For propylthiouracil and methimazole: Less than 1% of patients experience the following adverse reactions: agranulocytosis agranulocytosis (əgrăn'yəlōsītō`sis), disease in which the production of granulated white blood cells by the bone marrow is impaired. (O.3%-1%), arthralgia arthralgia /ar·thral·gia/ (ahr-thral´jah) pain in a joint. ar·thral·gia n. Severe pain in a joint. Also called arthrodynia. , cholestatic hepatitis, jaundice jaundice (jôn`dĭs, jän`–), abnormal condition in which the body fluids and tissues, particularly the skin and eyes, take on a yellowish color as a result of an excess of bilirubin. , myalgia myalgia /my·al·gia/ (mi-al´jah) muscular pain.myal´gic epidemic myalgia see under pleurodynia. my·al·gia n. , nephritis nephritis (nəfrī`təs), inflammation of the kidney. The earliest finding is within the renal capillaries (glomeruli); interstitial edema is typically followed by interstitial infiltration of lymphocytes, plasma cells, eosinophils, and a , or taste disturbances. Rash occurs in 5%-6% of patients. For sodium iodide I (131): Adverse effects are infrequent, except with large doses. Cough, neck tenderness and swelling, pain with swallowing, and sore throat may be seen three days after treatment. Temporary hair loss has been noted 2-3 months after treatment. Anemia and other blood dyscrasias are possible, especially with large doses. Drug-Drug Interactions INR INR In currencies, this is the abbreviation for the Indian Rupee. Notes: The currency market, also known as the Foreign Exchange market, is the largest financial market in the world, with a daily average volume of over US $1 trillion. may be increased in patients taking warfarin warfarin (wôr`fərĭn), anticoagulant used to treat blood clots. In large doses it causes bleeding. Warfarin, mixed with bait, is used in rodent control. warfarin Anticoagulant drug, marketed as Coumadin. in combination with propyithiouracil. Other Points of Interest Prothrombin time should be monitored in patients undergoing surgery who are taking propylthiouracil, as it may cause hypopro-thrombinemia and increased bleeding risk.
TABLE.
Antithyroid Medication Products Available and Dosage
Drug Trade Names
Propylthiouracil Generic
Methimazole Tapazole
Sodium iodide [I.sup.131] Iodotope, Sodium
iodide [I.sup.131]
thera-
just peutic
Drug Initial Dose
Propylthiouracil 300 mg/day (with large
goiters 400 mg/day) in
three divided doses
Methimazole 15 mg/day for mild,
30-40 mg/day for moderate,
and 60 mg/day for severe
hyperthyroidism. Should be
given in three divided doses.
Sodium iodide [I.sup.131] Variable dose:
Graves' disease ~ 10 MCi;
just Multinodular goiter
and thyrotoxicosis ~ 30 Mci;
Thyroid cancer~100-150 MCi
Drug Maintenance Dose Comments
Propylthiouracil 100-150 mg/day Some patients may require
initial doses of 600-1,200
mg/day
Methimazole 5-15 mg/day
Sodium iodide [I.sup.131] N/A Dose must be calibrated for
appropriate radioactivity
just before administration
References (1.) Hutchison TA, Shahan DR, Anderson ML (Eds): DRUGDEX System. MICROMEDEX, Inc., Englewood, Colo St. Louis, MO (2001) (2.) Hebel SK, Katstrup EK (Eds): Drug Facts and Comparisons: St. Louis, MO (2001) |
|
||||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion