Indications
Hypothyroidism
SYNTHROID® (levothyroxine sodium) tablets for oral use is an L-thyroxine (T4) indicated in adult and pediatric patients, including neonates, as a replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism.
Pituitary Thyrotropin (Thyroid Stimulating Hormone, TSH) Suppression
SYNTHROID is indicated in adult and pediatric patients, including neonates, as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer.
Limitation of Use
SYNTHROID is not indicated for suppression of benign thyroid nodules and nontoxic diffuse goiter in iodine-sufficient patients, as there are no clinical benefits and overtreatment with SYNTHROID may induce hyperthyroidism.
SYNTHROID is not indicated for treatment of hypothyroidism during the recovery phase of subacute thyroiditis.
Important Safety Information
WARNING:
Thyroid hormones, including SYNTHROID, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight loss. In euthyroid patients, doses within the range of daily hormonal requirements are ineffective for weight reduction. Larger doses may produce serious or even life-threatening manifestations of toxicity, particularly when given in association with sympathomimetic amines such as those used for their anorectic effects.
CONTRAINDICATIONS
- SYNTHROID is contraindicated in patients with uncorrected adrenal insufficiency.
WARNINGS AND PRECAUTIONS
- SYNTHROID has a narrow therapeutic index. Overtreatment or undertreatment with SYNTHROID may have negative effects on growth and development, cardiovascular function, bone metabolism, reproductive function, cognitive function, gastrointestinal function, and glucose and lipid metabolism in adult or pediatric patients. In pediatric patients with congenital and acquired hypothyroidism, undertreatment may adversely affect cognitive development and linear growth, and overtreatment is associated with craniosynostosis and acceleration of bone age. Titrate the dose of SYNTHROID carefully and monitor response to titration to avoid these effects.
- In the elderly and in patients with cardiovascular disease, SYNTHROID should be initiated at lower doses than those recommended in younger individuals or in patients without cardiac disease. If cardiac symptoms develop or worsen, the SYNTHROID dose should be reduced or withheld for one week and restarted at a lower dose.
- Patients with coronary artery disease who are receiving SYNTHROID should be monitored closely during surgical procedures for cardiac arrhythmias. Monitor patients during concomitant administration of SYNTHROID and sympathomimetic agents for signs and symptoms of coronary insufficiency.
- Use of oral thyroid hormone is not recommended in myxedema coma. Products formulated for IV administration should be used to treat myxedema coma.
- Patients with adrenal insufficiency should be treated with replacement glucocorticoids prior to initiating treatment with SYNTHROID. Failure to do so may precipitate an acute adrenal crisis when thyroid hormone therapy is initiated.
- Addition of levothyroxine therapy in patients with diabetes mellitus may worsen glycemic control and result in increased antidiabetic agent or insulin requirements. Carefully monitor glycemic control after starting, changing, or discontinuing SYNTHROID.
- Increased bone resorption and decreased bone mineral density may occur as a result of levothyroxine over-replacement, particularly in postmenopausal women. To mitigate this risk, patients receiving SYNTHROID should be given the minimum dose necessary that achieves the desired response.
ADVERSE REACTIONS
- Adverse reactions associated with SYNTHROID therapy are primarily those of hyperthyroidism due to therapeutic overdosage.
- In pediatric patients receiving levothyroxine therapy, pseudotumor cerebri and slipped capital femoral epiphysis have been reported. Overtreatment may result in craniosynostosis in infants who have not undergone complete closure of the fontanelles, and in premature closure of the epiphyses in pediatric patients still experiencing growth with resultant compromised adult height.
DRUG INTERACTIONS
- Many drugs and some foods affect thyroid hormone pharmacokinetics and metabolism and may alter the therapeutic response to SYNTHROID. In addition, thyroid hormones and thyroid status have varied effects on the pharmacokinetics and actions of other drugs. Administer at least 4 hours before or after drugs that are known to interfere with absorption. Evaluate the need for dose adjustments when regularly administering within one hour of certain foods that may affect absorption. Prescribers should consult appropriate reference sources for additional information on drug or food interactions with SYNTHROID.
USE IN SPECIFIC POPULATIONS
- SYNTHROID should not be discontinued during pregnancy, and hypothyroidism diagnosed during pregnancy should be promptly treated. TSH levels may increase during pregnancy, so TSH should be monitored and SYNTHROID dose adjusted as needed.
US-SYNT-220356