SYNTHROID(levothyroxine sodium tablets, USP)
SYNTHROID Rx

Generic Name and Formulations:

Levothyroxine sodium 25mcg, 50mcg (dye-free), 75mcg, 88mcg, 100mcg, 112mcg, 125mcg, 137mcg, 150mcg, 175mcg, 200mcg, 300mcg; scored tabs.

Company:

AbbVie
Indications for SYNTHROID:

Hypothyroidism.

Adult:

Take in AM on empty stomach, ½ to 1hr before breakfast. Individualize. Primary hypothyroidism: 1.6mcg/kg once daily; titrate in increments of 12.5–25mcg every 4–6 weeks until euthyroid and serum TSH normalized. Elderly or underlying cardiovascular disease: initially 12.5–25mcg once daily; titrate every 6–8 weeks until euthyroid and serum TSH normalized. Usual max 200mcg/day. Severe hypothyroidism: initially 12.5–25mcg once daily; titrate in increments of 12.5–25mcg every 2–4 weeks until euthyroid and serum TSH normalized. Secondary or tertiary hypothyroidism: see full labeling.

Children:

Take in AM on empty stomach, ½ to 1hr before breakfast. May crush tabs and mix in 5–10mL water. Congenital or acquired hypothyroidism: 0–3months: 10–15mcg/kg per day; 3–6months: 8–10mcg/kg per day; 6–12months: 6–8mcg/kg per day; 1–5yrs: 5–6mcg/kg per day; 6–12yrs: 4–5mcg/kg per day; >12yrs but growth and puberty incomplete: 2–3mcg/kg per day; growth and puberty complete: as adult. Newborns at risk for cardiac failure: initiate at lower dose; increase dose every 4–6 weeks as needed. Risk for hyperactivity: initially ¼ full replacement dose; increase by ¼ dose weekly until full dose reached.

Contraindications:

Uncorrected adrenal insufficiency.

Warnings/Precautions:

Not for treatment of obesity or weight loss. Adults: Monitor TSH 6–8 weeks after dose change then every 6–12 months. Peds: Monitor TSH 2 and 4 weeks after initiation, 2 weeks after dose change then every 3–12 months thereafter. Cardiovascular disease; monitor for cardiac arrhythmias during surgery. Reduce or withhold dose for 1 week if cardiac symptoms develop or worsen; restart at lower dose. Tabs: not for treating myxedema coma. Correct adrenal insufficiency before initiation. Increased sensitivity in severe hypothyroidism. Diabetes; monitor glucose control. Use lowest effective dose. Elderly. Pregnancy: monitor TSH at least every trimester; adjust dose and do not discontinue (see full labeling). Nursing mothers.

Interactions:

See full labeling. Absorption reduced by some foods (eg, soy flour, cottonseed meal, walnuts, fiber, grapefruit juice), aluminum and magnesium hydroxide, simethicone, proton pump inhibitors, iron, sucralfate; monitor. Give at least 4hrs apart from calcium carbonate, ferrous sulfate, bile acid sequestrants (eg, colesevelam, cholestyramine, colestipol), ion exchange resins (eg, kayexalate, sevelamer). Potentiates, and is potentiated by, tri- and tetracyclic antidepressants. Concomitant sympathomimetics; monitor for coronary insufficiency. Antagonized by phenobarbital, rifampin, sertraline. Antagonizes digitalis glycosides. Marked hypertension and tachycardia with ketamine. Hypothyroidism risk with concomitant tyrosine kinase inhibitors (eg, imatinib). Estrogens, androgens, corticosteroids affect thyroid function tests. Monitor oral anticoagulants, antidiabetic agents, orlistat.

See Also:

Levothyroxine sodium Injection

Pharmacological Class:

T4 (synthetic).

Adverse Reactions:

Arrhythmias, myocardial infarction, dyspnea, muscle spasm, headache, nervousness, irritability, insomnia, tremors, muscle weakness, increased appetite, weight loss, diarrhea, heat intolerance, menstrual irregularities, skin rash; seizures (rare); Children: pseudotumor cerebri, slipped capital femoral epiphysis.

Generic Availability:

YES

How Supplied:

Tabs (all)—90, 1000; Tabs (25mcg, 50mcg, 75mcg, 88mcg, 100mcg, 125mcg, 175mcg)—100; Single-use vials—1