levothyroxine sodium

Also found in: Dictionary.

levothyroxine sodium (L-thyroxine, T4)

Eltroxin (CA) (UK), Euthyrox (CA), Evotrox (UK), Levo-T, Levolet, Levothroid, Levoxyl, Nu-Thyro (CA), Soloxine, Synthroid, Unithroid

Pharmacologic class: Synthetic thyroxine hormone

Therapeutic class: Thyroid hormone replacement

Pregnancy risk category A

FDA Box Warning

• Drug shouldn't be used alone or with other agents to treat obesity or weight loss. In euthyroid patients, doses within range of daily hormonal requirements are ineffective for weight loss. Larger doses may cause serious or life-threatening toxicity, particularly when given with sympathomimetic amines (such as those used for anorectic effects).


Synthetic form of thyroxine that replaces endogenous thyroxine, increasing thyroid hormone levels. Thyroid hormones help regulate cell growth and differentiation and increase metabolism of lipids, protein, and carbohydrates.


Powder for injection: 200 mcg/vial in 6- and 10-ml vials, 500 mcg/vial in 6- and 10-ml vials

Tablets: 25 mcg, 50 mcg, 75 mcg, 88 mcg, 100 mcg, 112 mcg, 125 mcg, 137 mcg, 150 mcg, 175 mcg, 200 mcg, 300 mcg

Indications and dosages

Hypothyroidism; treatment or prevention of euthyroid goiter

Adults: For healthy adults younger than age 50 and those over age 50 who have recently been treated or undergone short-term therapy, start at full replacement dosage of 1.7 mcg/kg P.O. daily, given 30 minutes to 1 hour before breakfast. For patients older than age 50 or younger than age 50 with heart disease, 25 to 50 mcg P.O. daily, increased q 4 to 6 weeks. In severe hypothyroidism, initial dosage is 12.5 to 25 mcg P.O. daily, adjusted by 25 mcg daily q 2 to 4 weeks. For patients who can't tolerate oral doses, adjust I.M. or I.V. dosage to roughly half of oral dosage.

Congenital hypothyroidism

Children older than age 12 who have completed puberty and growth: 1.7 mcg/kg P.O. daily

Children older than age 12 who have not completed puberty and growth: Up to 150 mcg or 2 to 3 mcg/kg P.O. daily

Children ages 6 to 12: 4 to 5 mcg/kg P.O. daily

Children ages 1 to 5: 5 to 6 mcg/kg P.O. daily

Infants ages 6 to 12 months: 6 to 8 mcg/kg P.O. daily

levothyroxine sodium

a thyroid hormone. Also called l -thyroxine.
indication It is prescribed in the treatment of hypothyroidism.
contraindications Recent myocardial infarction or known hypersensitivity to this drug prohibits its use.
adverse effects The most serious adverse effects are angina, tachycardia, arrhythmias, and tremors.

levothyroxine sodium

(lē″vō-thī-rok′sēn″, sĕn) [ levo- + thyroxine],


The sodium salt of the natural isomer of thyroxine used to treat thyroid deficiency. A typical dosage used to treat hypothyroidism is1.6 mcg/kg/day given orally.

levothyroxine sodium (lē´vōthīrak´sēn),

n brand names: Levo-T, Synthroid;
drug class: thyroid hormone;
action: increases metabolic rate, with increase in cardiac output, O2 consumption, body temperature, blood volume, growth/development at cellular level;
uses: hypothroidism, myxedema coma, thyroid hormone replacement, cretinism.
References in periodicals archive ?
As of January 2007, four branded oral L-T4 products were available in the United States: levothyroxine sodium (Unithroid, Levoxyl, Synthroid and Levothroid).
As the sole manufacturer of Levothyroxine Sodium for Injection, APP Pharmaceuticals will be introducing an extension of its current product line in the next several months.
Due to the long half-life of levothyroxine, the peak therapeutic effect at a given dose of levothyroxine sodium may not be attained for 4-6 weeks.
An FDA spokesperson said that the "FDA believes that requiring all marketed levothyroxine sodium products to adhere to a tighter potency specification will minimize any clinical differences that may result from switching between different levothyroxine sodium products or refilling a prescription with the same prescribed product.
clopidogrel bisulfate, levothyroxine sodium, Montelukast sodium
A 10% loss in potency over the shelf life of levothyroxine sodium products--the maximum amount allowed under current regulations--raises clinically significant concerns, and current potency specifications for these products should be tightened, according to a majority of two Food and Drug Administration advisory panels.
She had received oral levothyroxine sodium in doses as high as 600 [micro]g along with 100 [micro]g of triiodothyronine daily with no symptomatic improvement; she had a persistently elevated TSH level as high as 607 IU/mL (normal, 0.
AMEX: LCI) today said it is encouraged by a legal development in Florida that could remove generic Levothyroxine Sodium from the state's negative drug formulary.
Bedrosian added, "Sales of our Levothyroxine sodium product, the only Levothyroxine product of its kind on the market that meets the FDA's new and more stringent standards throughout its 24-month expiry, are growing.
Studies in women taking levothyroxine sodium during pregnancy have not shown an increased risk of congenital abnormalities.
AMEX:LCI), a manufacturer of generic pharmaceuticals, is pleased to comment on the recent Food and Drug Administration (FDA) announcement regarding Levothyroxine sodium.