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February 3, 2012
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levothyroxine sodium, Synthroid, Levoxyl, Levothroid, Unithroid

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GENERIC NAME: levothyroxine sodium

BRAND NAME: Synthroid, Levoxyl, Levothroid, Unithroid

DRUG CLASS AND MECHANISM: Levothyroxine is a synthetic (man-made) version of the principle thyroid hormone, thyroxine (T4) that is made and released by the thyroid gland. Thyroid hormone increases the metabolic rate of cells of all tissues in the body. In the fetus and newborn, thyroid hormone is important for the growth and development of all tissues including bones and the brain. In adults, thyroid hormone helps to maintain brain function, food metabolism, and body temperature, among other effects.

GENERIC AVAILABLE: Yes. Generic and branded tablets of levothyroxine may differ:

  • in the amount of levothyroxine they contain,

  • the absorption of the levothyroxine into the body, and

  • the distribution of levothyroxine throughout the body.

This means that ingestion of 1 mg of generic levothyroxine may not have the same effect on the body as 1 mg of another generic or branded levothyroxine. Practically speaking, this means that when changing between levothyroxine manufactured by different pharmaceutical companies, a change in dose may be necessary to maintain the desired effect, or to prevent toxicity.

PRESCRIPTION: Yes.

PREPARATIONS: Tablets: 0.025, 0.05, 0.075, 0.088, 0.1, 0.112, 0.125, 0.137, 0.15, 0.175, 0.2, and 0.3 mg. Powder for intravenous injection: 200 mcg and 500 mcg per vial.

STORAGE: Levothyroxine tablets and dry powder should be kept at room temperature, 15-30°C (59-86°F) in a light-resistant, tight container.

Powdered levothyroxine for intravenous injection should be used immediately once mixed with a liquid.

PRESCRIBED FOR: Levothyroxine is approved to treat hypothyroidism and to suppress thyroid hormone release in the management of cancerous thyroid nodules and growth of goiters. In addition, Synthroid, Levoxyl and Levothroid also are prescribed with anti-thyroid drugs, for example methimazole (Tapazole), to manage thyrotoxicosis (high thyroid hormone levels due to over-activity of the thyroid gland). Thyrotoxicosis may result in the growth of goiters and/or hypothyroidism.

DOSING: For adult hypothyroidism levothyroxine is started at 12.5-125 mcg/day administered orally. Starting doses and dose changes may differ with individual patients based upon age, the presence of cardiovascular disease, the development of tolerance (reduced effectiveness with continued use), side effects to the medication, and blood levels of thyroid hormone. It may take one to three weeks after initiating therapy with levothyroxine or changing the dose before effects are seen. The goal of replacement therapy is to maintain a normal blood thyroxine level.

DRUG INTERACTIONS: Initiation or discontinuation of therapy with levothyroxine in diabetic patients may create a need for an increase or decrease in the required dose of insulin and/or antidiabetic drug, [for example, glyburide (Micronase)].

Levothyroxine may increase the effect of blood thinners such as warfarin (Coumadin). Therefore, monitoring of blood clotting is necessary, and a decrease in the dose of warfarin may be necessary.

Intravenous administration of epinephrine to patients with coronary artery disease may lead to complications ranging from difficulty in breathing to a heart attack. These complications may occur more frequently among patients also taking levothyroxine. Therefore, careful observation is needed when intravenous epinephrine is given to patients receiving levothyroxine who also have coronary artery disease.




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Suggested Reading on levothyroxine sodium, Synthroid, Levoxyl, Levothroid, Unithroid by Our Doctors

  • Related Diseases & Conditions

    • Hypothyroidism
      • Hypothyroidism is any state in which thyroid hormone production is below normal. Normally, the rate of thyroid hormone production is controlled by the brain at the pituitary. Hypothyroidism is a very common condition and the symptoms of hypothyroidism are often subtle.
    • Hashimoto's Thyroiditis
      • Hashimoto's thyroiditis is the most common cause of hypothyroidism in the US. This conditions is caused by inflammation of the thyroid gland. Symptoms may include: fatigue, weight gain, cold intolerance, excessive sleepiness, dry or coarse hair, difficulty swallowing, a lump in the front of the throat, and many more. Treatment is usually hypothyroid medication.
    • Thyroid Nodules
      • Thyroid nodules are the most common endocrine problem in the United States. The term "thyroid nodule" refers to any abnormal growth that forms a lump in the thyroid gland. The vast majority of thyroid nodules are benign.
    • Thyroid Disease
      • There are many types of thyroid disease. Some occur due to the function of the thyroid itself such as hypothyroidism, hyperthyroidism, Hashimoto's thyroiditis, etc. Some causes of thyroid disease occur due to problems with the structure of the thyroid gland such as goiters, thyroid nodules, and thyroid cancer. Treatment of thyroid disease depends on the cause of the disease.
    • Hypothyroidism During Pregnancy
      • Hypothyroidism during pregnancy can be treated with synthetic thyroid hormones to maintain the proper thyroid hormone balance. Hypothyroidism symptoms include fatigue, weight gain, lethargy, and constipation. Treatment of hypothyroidism in pregnant women is important, because inadequate levels of thyroid hormones may affect the fetus, and child during growth and development.
    • Thyroiditis
      • Thyroiditis is the inflammation of the thyroid gland. The inflamed thyroid gland can release an excess of thyroid hormones into the blood stream, resulting in a temporary hyperthyroid state. Some forms of thyroiditis can be diagnosed based on tenderness and enlargement of the thyroid gland. A thyroid scan sometimes is used in making the diagnosis. Thyroiditis can also be diagnosed with a biopsy of the thyroid gland.
    • Pendred Syndrome
      • Pendred syndrome, a genetic disorder that causes hearing loss. Generally, the hearing loss is affected in early childhood. Pendred syndrome also affects other parts fo the body (for example, the thyroid gland). Treatment is generally cochlear ear implants.
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Related Drugs - WebMD Health Network

levothyroxine sodium, Synthroid, Levoxyl, Levothroid, Unithroid

What is thyroiditis?

Thyroiditis (thy-roi-DY-tiss) is inflammation, or swelling, of the thyroid. There are several types of thyroiditis, one of which is Hashimoto's thyroiditis.

What are other types and symptoms of thyroiditis?

Postpartum thyroiditis

Like Hashimoto's thyroiditis, postpartum thyroiditis seems to be caused by a problem with the immune system. In the United States, postpartum thyroiditis occurs in about 5 to 10 percent of women. The first phase starts 1 to 4 months after giving birth. In this phase, you may get symptoms of hyperthyroidism because the damaged thyroid is leaking thyroid hormones out into the bloodstream. The second phase starts about 4 to 8 months after delivery. In this phase, you may get symptoms of hypothyroidism because, by this time, the thyroid has lost most of its hormones. Not everyone with postpartum thyroiditis goes through both phases. In most women who ha...

Read the Thyroiditis article »







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