SYNTHROID®levothyroxine sodium tablets, USP

The relative bioavailability of levothyroxine sodium tablets, compared to an equal nominal dose of oral levothyroxine sodium solution, is approximately 93%. T4 absorption is increased by fasting, and decreased in malabsorption syndromes and by certain foods such as soybeans. In addition, many drugs and foods affect T4 absorption see Drug Interactions (7) . Rapid restoration of normal serum T4 concentrations is essential for preventing the adverse effects of congenital hypothyroidism on cognitive development as well as on overall physical growth and maturation. Therefore, initiate levothyroxine sodium tablets therapy immediately upon diagnosis. Levothyroxine is generally continued for life in these patients see Warnings and Precautions (5.1) .

3 Oral Anticoagulants

• 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).
• However, long-term glucocorticoid therapy may result in slightly decreased T3 and T4 levels due to decreased TBG production (See above).
• When prescribing SYNTHROID, protecting your script can ensure your patients receive SYNTHROID every time they refill their prescription.
• The recommended daily dosage of SYNTHROID in pregnant patients is described in Table 3.

In patients with secondary or tertiary hypothyroidism, additional hypothalamic/pituitary hormone deficiencies should be considered, and, if diagnosed, treated (see PRECAUTIONS – Autoimmune polyglandular syndrome for adrenal insufficiency). The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for SYNTHROID and any potential adverse effects on the breastfed infant from SYNTHROID or from the underlying maternal condition. Pseudotumor cerebri and slipped capital femoral epiphysis synthroid pcos have been reported in pediatric patients receiving levothyroxine therapy. Carefully monitor glycemic control after starting, changing, or discontinuing SYNTHROID see Drug Interactions (7.2). Treat patients with adrenal insufficiency with replacement glucocorticoids prior to initiating treatment with SYNTHROID see Contraindications (4).

Careful titration of medication and monitoring is required in that setting. It occurs more in the elderly and is much more common in women than men. We anticipate reposting the images once we are able identify and filter out images that do not match the information provided in the drug labels. The presence of concomitant medical conditions should be considered in certain clinical circumstances and, if present, appropriately treated (see PRECAUTIONS ).

4 Monitoring TSH and/or Thyroxine (T Levels

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.

• Closely monitor infants during the first 2 weeks of SYNTHROID therapy for cardiac overload and arrhythmias.
• Levothyroxine, at doses individualized according to patient response, is effective as replacement or supplemental therapy in hypothyroidism of any etiology, except transient hypothyroidism during the recovery phase of subacute thyroiditis.
• If so, advise them to stop biotin supplementation at least 2 days before assessing TSH and/or T4 levels see Dosage and Administration (2.4) and Drug Interactions (7.10).
• Concurrent use of sympathomimetics and levothyroxine sodium tablets may increase the effects of sympathomimetics or thyroid hormone.
• Serum TSH levels should be monitored and the SYNTHROID dosage adjusted during pregnancy.

The higher affinity of both TBG and TBPA for T4 partially explains the higher serum levels, slower metabolic clearance, and longer half-life of T4 compared to T3. Protein-bound thyroid hormones exist in reverse equilibrium with small amounts of free hormone. Many drugs and physiologic conditions affect the binding of thyroid hormones to serum proteins see Drug Interactions (7) . Thyroid hormones do not readily cross the placental barrier see Use in Specific Populations (8.1) .

Information for Patients

Levothyroxine is contraindicated in patients with untreated subclinical (suppressed serum TSH level with normal T3 and T4 levels) or overt thyrotoxicosis of any etiology and in patients with acute myocardial infarction. Levothyroxine is contraindicated in patients with uncorrected adrenal insufficiency since thyroid hormones may precipitate an acute adrenal crisis by increasing the metabolic clearance of glucocorticoids (see PRECAUTIONS). SYNTHROID is contraindicated in patients with hypersensitivity to any of the inactive ingredients in SYNTHROID tablets (See DESCRIPTION – Inactive Ingredients ). Absorption of orally administered T4 from the gastrointestinal (GI) tract ranges from 40% to 80%. The majority of the levothyroxine dose is absorbed from the jejunum and upper ileum. The relative bioavailability of SYNTHROID tablets, compared to an equal nominal dose of oral levothyroxine sodium solution, is approximately 93%.

The 25 mcg tablets are orange, capsule-shaped, scored tablets debossed with L to the left of the score and to the right of the score on one side of the tablet and M on the other side. Levothyroxine Sodium Tablets, USP are available containing 25 mcg, 50 mcg, 75 mcg, 88 mcg, 100 mcg, 112 mcg, 125 mcg, 137 mcg, 150 mcg, 175 mcg, 200 mcg or 300 mcg of levothyroxine sodium, USP. Treated children may manifest a period of catch-up growth, which may be adequate in some cases to normalize adult height. In children with severe or prolonged hypothyroidism, catch-up growth may not be adequate to normalize adult height. Closely monitor infants during the first 2 weeks of SYNTHROID therapy for cardiac overload and arrhythmias.

Use our dose calculator for adults

Symptoms may not necessarily be evident or may not appear until several days after ingestion of levothyroxine sodium. Administer SYNTHROID to pediatric patients who cannot swallow intact tablets by crushing the tablet, suspending the freshly crushed tablet in a small amount (5 to 10 mL) of water and immediately administering the suspension by spoon or dropper. Do not administer in foods that decrease absorption of SYNTHROID, such as soybean-based infant formula see Drug Interactions ( 7.9) . The signs and symptoms of overdosage are those of hyperthyroidism (see PRECAUTIONS and ADVERSE REACTIONS). The initial dose of levothyroxine varies with age and body weight (see DOSAGE AND ADMINISTRATION – Table 3). Dosing adjustments are based on an assessment of the individual patient’s clinical and laboratory parameters (see PRECAUTIONS – Laboratory Tests).

Levothyroxine sodium tablets are indicated in adult and pediatric patients, including neonates, as a replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism. The goal of replacement therapy is to achieve and maintain a clinical and biochemical euthyroid state. The goal of suppressive therapy is to inhibit growth and/or function of abnormal thyroid tissue.

The goal of treatment in pediatric patients with hypothyroidism is to achieve and maintain normal intellectual and physical growth and development. Exercise caution when administering levothyroxine to patients with nontoxic diffuse goiter or nodular thyroid disease in order to prevent precipitation of thyrotoxicosis (see WARNINGS ). If the serum TSH is already suppressed, levothyroxine sodium should not be administered (see CONTRAINDICATIONS ). The signs and symptoms of overdosage are those of hyperthyroidism see Warnings and Precautions (5) and Adverse Reactions (6). Do not administer in foods that decrease absorption of SYNTHROID, such as soybean-based infant formula see Drug Interactions (7.9). Overtreatment or undertreatment with levothyroxine may have negative effects on different systems throughout the human body.