Dosing & Administration

Closely monitor coagulation tests to permit appropriate and timely dosage adjustments. For pregnant patients with pre-existing hypothyroidism, measure serum TSH and free-T4 as soon as pregnancy is confirmed and, at minimum, during each trimester of pregnancy. In pregnant patients with primary hypothyroidism, maintain serum TSH in the trimester-specific reference range. For adult patients with primary hypothyroidism, titrate until the patient is clinically euthyroid and the serum TSH returns to normal.

FDA Drug Information

Tell your doctor if you have an untreated or uncontrolled adrenal gland disorder or any heart problems such as a recent heart attack. Euthyrox (levothyroxine) is used to treat hypothyroidism and to treat or prevent goiter. This is not a complete list of side effects and others may occur. Levothyroxine injection is used in adults to treat myxedema coma. Additional laboratory testing and clinical findings may be necessary.

For adult patients with primary hypothyroidism, titrate until the patient is clinically euthyroid and the serum TSH returns to normal see Dosage and Administration (2.3). Synthroid is a medication that replaces hormones produced by your body. It is often prescribed to treat thyroid problems, but can be used to treat a variety of other medical issues, including diabetes, kidney and liver conditions, osteoporosis, problems with the adrenal or pituitary gland, and more. If you take it according to your doctor’s instructions, it is relatively safe, but you may need to manage some minor side effects. Get medical help right away if you notice any serious side effects, like an allergic reaction or chest pain, while taking synthroid.

Consider changes in TBG concentration when interpreting T4 and T3 values. Measure and evaluate unbound (free) hormone and/or determine the free-T4 index (FT4I) in this circumstance. Pregnancy, infectious hepatitis, estrogens, estrogen-containing oral contraceptives, and acute intermittent porphyria increase TBG concentration. Nephrosis, severe hypoproteinemia, severe liver disease, acromegaly, androgens, and corticosteroids decrease TBG concentration. Familial hyper- or hypo-thyroxine binding globulinemias have been described, with the incidence of TBG deficiency approximating 1 in 9000.

Pregnancy

Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of levothyroxine in children. However, your child’s doctor will check your child closely for heart problems during the first 2 weeks of treatment. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.

• Levothyroxine is one of the ten NTI drug classes most commonly prescribed.
• Additionally, levothyroxine has FDA approval for pituitary thyrotropin suppression as an adjunct to surgery and radioiodine therapy to manage thyrotropin-dependent well-differentiated thyroid cancer.
• Titrate the dosage (every 2 weeks) as needed based on serum TSH or free- T4 until the patient is euthyroid see Important Considerations For Dosing.

Consider the potential for food or drug interactions and adjust the administration or dosage of SYNTHROID as needed see Dosage and Administration (2.1), Drug Interactions (7.1), and Clinical Pharmacology (12.3). Do not administer in foods that decrease absorption of SYNTHROID, such as soybean-based infant formula see Drug Interactions (7.9). Do not administer in foods that decrease absorption of SYNTHROID, such as soybean-based infant formula. Levothyroxine is one of the ten NTI drug classes most commonly prescribed. These medications are those where small changes in the dose or blood concentration may lead to serious therapeutic failures and/or adverse drug reactions. Many drugs can inhibit Synthroid’s adsorption by the body; other medications may increase or decrease its effectiveness once it is adsorbed.

No adverse effects on the breastfed infant have been reported and there is no information on the effects of levothyroxine on milk production. Adequate levothyroxine treatment during lactation may normalize milk production in hypothyroid lactating mothers with low milk supply. Hypersensitivity reactions to inactive ingredients have occurred in patients treated with thyroid hormone products. These include urticaria, pruritus, skin rash, flushing, angioedema, various gastrointestinal symptoms (abdominal pain, nausea, vomiting and diarrhea), fever, arthralgia, serum sickness, and wheezing. Hypersensitivity to levothyroxine itself is not known to occur.

Other Medical Problems

Cotton seed meal, dietary fiber, soybean flour (infant formula), or walnuts may decrease the absorption of this medicine from your body. You may have to take this medicine at a different time of day from when you eat these foods. The major pathway of thyroid hormone metabolism is through sequential deiodination. Approximately 80% of circulating T3 is derived from peripheral T4 by monodeiodination.

• Do not administer in foods that decrease absorption of SYNTHROID, such as soybean-based infant formula see DRUG INTERACTIONS.
• It is also not indicated for the treatment of hypothyroidism during the recovery phase of subacute thyroiditis.
• Taking more than your recommended dose will not make this medicine more effective, and may cause serious side effects.
• Review of the history should be carried out to ensure the patient has not received iodine-containing contrast (e.g. for CT or angiography).
• Medications such as amiodarone, potassium iodide and some vitamin supplements should be ceased if safe to do so prior to scan.
• This document does not contain all possible side effects and others may occur.

Pituitary Thyrotropin (Thyroid-Stimulating Hormone, TSH) Suppression

Symptoms may not necessarily be evident or may not appear until several days after ingestion of levothyroxine sodium. Titrate the dose of SYNTHROID carefully and monitor response to titration to avoid these effects see DOSAGE AND ADMINISTRATION. Consider the potential for food or drug interactions and adjust the administration or dosage of SYNTHROID as needed see DOSAGE AND ADMINISTRATION, DRUG INTERACTIONS and CLINICAL PHARMACOLOGY.

For non-prescription products, read the label or package ingredients carefully. Oral levothyroxine sodium is a synthetic T4 hormone that exerts the same physiologic effect as endogenous T4, thereby maintaining normal T4 levels when a deficiency is present. Reduce the SYNTHROID dosage or discontinue temporarily synthroid tramadol if signs or symptoms of overdosage occur. Initiate appropriate supportive treatment as dictated by the patient’s medical status.