Thyroid supplements. (Medication Update).Mode of Action Replacement of thyroid hormones normally synthesized by the body. Contraindications In patients with untreated acute myocardial infarction acute myocardial infarction (  ·kyōōtˑ mī·ō·karˑ·dē· , adrenal adrenal /ad·re·nal/ (ah-dre´n'l)1. paranephric. 2. adrenal gland. 3. pertaining to an adrenal gland. ad·re·nal adj. 1. cortical insufficiency, angina, hypertension, and thyrotoxicosis thyrotoxicosis /thy·ro·tox·i·co·sis/ (thi?ro-tok?si-ko´sis) a morbid condition due to overactivity of the thyroid gland; see Graves' disease. thy·ro·tox·i·co·sis n. . 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 thyroid supplement or components of their formulation. Pregnancy category: A. Adverse Effects Adverse reactions are generally due to excessive doses of thyroid hormones and manifest as hyperthyroidism hyperthyroidism: see thyroid gland. (eg, angina, diarrhea, headache, heart palpitations, heat intolerance, nervousness, tachycardia tachycardia: see arrhythmia. tachycardia Heart rate over 100 (as high as 240) beats per minute. When it is a normal response to exercise or stress, it is no danger to healthy people, but when it originates elsewhere, it is an arrhythmia. , tremors, vomiting, and weight loss). Drug-Drug Interactions Cholestyramine cholestyramine /cho·le·sty·ra·mine/ (ko?le-sti´rah-men) see cholestyramine resin, under resin. cho·le·styr·a·mine n. , colestipol, and estrogens Estrogens Hormones produced by the ovaries, the female sex glands. Mentioned in: Acne, Polycystic Ovary Syndrome estrogens (es´trōjenz), n. may decrease the effectiveness of thyroid hormones. Thyroid hormones may increase the effectiveness of 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. and theophylline theophylline /the·oph·yl·line/ (the-of´i-lin) a xanthine derivative found in tea leaves and prepared synthetically; its salts and derivatives act as smooth muscle relaxants, central nervous system and cardiac muscle stimulants, and . Dose adjustments of warfarin and theophylline may be necessary when thyroid hormones are initiated or changed. Thyroid hormones may decrease the effectiveness of beta blockers and digoxin digoxin: see digitalis. . Dose adjustments of beta blockers and digoxin may be necessary when thyroid hormones are initiated or changed. Other Points of Interest Some thyroid preparations contain tartrazine tartrazine FD&C Yellow No. 5, see there , which may cause allergic reactions in sensitive patients.
TABLE.
Thyroid Supplement Products Available and Dosage
Drug Trade Names
Desiccated thyroid Armour thyroid,
Thyroid USP, Thyroid
strong, Thyrar, S-P-T
Levothyroxine Eltroxin, Levo-T,
([T.sub.4], L-thyroxine) Levothroid, Levoxyl,
Synthroid, and generic
Liothyronine Cytomel, Triostat,
sodium ([T.sub.3]) and generic
Liotrix Thyrolar
([T.sub.4] and [T.sub.5]
combination)
Drug Initial Dose
Desiccated thyroid 30 mg QD (15 mg QD if
long-standing myxedema
or cardiovascular
impairment present)
Levothyroxine 0.05 mg QD
([T.sub.4], L-thyroxine) [less than or equal to]
0.025 mg QD if
long-standing myxedema
or cardiovascular
impairment present)
Liothyronine 25 [micro]g QD (5
sodium ([T.sub.3]) [micro]g QD in myxedema,
elderly, simple goiter,
congenital hypothyroidism)
Liotrix 30 mg QD (15 mg QD if
([T.sub.4] and [T.sub.5] long-standing myxedema or
combination) cardiovascular impairment
present)
Drug Usual Dose
Desiccated thyroid 60-120 mg/day
Levothyroxine Adjust dose as
([T.sub.4], L-thyroxine) necessary, up to usual
maximum of 0.2 mg/day
Liothyronine Adjust dose as
sodium ([T.sub.3]) necessary, up to
usual maximum of
100 [micro]g/day
Liotrix 60-120 mg/day
([T.sub.4] and [T.sub.5]
combination)
Drug Comments
Desiccated thyroid Dose may be increased
by 15 mg/day every 2-3
weeks until desired
effect is achieved
Levothyroxine Dose may be increased
([T.sub.4], L-thyroxine) by 0.025 mg/day
every 2-3 weeks until
desired effect is
achieved.
Liothyronine Dose may be increased
sodium ([T.sub.3]) by 5-10 [micro]g/day
every 1-2 weeks until
25 [micro]g/day is reached,
then dose may be increased
by 12.5-25 [micro]g/day
every 1-2 weeks until
desired effect is
achieved
Liotrix Dose may be increased by
([T.sub.4] and [T.sub.5] 15 mg/day every 2-3
combination) weeks until desired
effect is achieved
References (1.) Hutchison TA, Shahan DR, Anderson ML (Eds): DRUGDEX System. MIGROMEDEX, Inc., Englewood, Cob (Edition expires 12/00) (2.) Hebel SK, Katstrup EK (Eds): Drug Facts and Comparisons. St. Louis, MO (2001) |
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