Liothyronine Sodium

RECENT MAJOR CHANGES Indications and Usage ( 1.1 , 1.2 , 1.3 ) 12/2018 Dosage and Administration ( 2.1 , 2.2 , 2.3 , 2.4 , 2.5 , 2.6 ) 12/2018 Contraindications ( 4 ) 12/2018 Warnings and Precautions ( 5.1 , 5.2 , 5.3 , 5.4 , 5.5 , 5.6 ) 12/2018

1 INDICATIONS AND USAGE Liothyronine sodium is an L-triiodothyronine (T3) indicated for: Hypothyroidism: As replacement in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism ( 1.1 ) Pituitary Thyrotropin (Thyroid-Stimulating Hormone, TSH) Suppression: As an adjunct to surgery and radioiodine therapy in the management of well-differentiated thyroid cancer ( 1.2 ) Thyroid Suppression Test: As a diagnostic agent in suppression tests to differentiate suspected mild hyperthyroidism or thyroid gland autonomy ( 1.3 ) Limitations of Use: - Not indicated for suppression of benign thyroid nodules and nontoxic diffuse goiter in iodine-sufficient patients. ( 1 ) - Not indicated for treatment of hypothyroidism during the recovery phase of subacute thyroiditis. ( 1 ) 1.1 Hypothyroidism Liothyronine Sodium Tablets, USP are indicated as a replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism. 1.2 Pituitary Thyrotropin (Thyroid-Stimulating Hormone, TSH) Suppression Liothyronine Sodium Tablets, USP are indicated as an adjunct to surgery and radioiodine therapy in the management of well-differentiated thyroid cancer. 1.3 Thyroid Suppression Test Liothyronine Sodium Tablets, USP are indicated as a diagnostic agent in suppression tests to differentiate suspected mild hyperthyroidism or thyroid gland autonomy. Limitations of Use Liothyronine Sodium Tablets, USP are 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 Liothyronine Sodium Tablets, USP may induce hyperthyroidism [see Warnings and Precautions (5.4) ]. Liothyronine Sodium Tablets, USP are not indicated for treatment of hypothyroidism during the recovery phase of subacute thyroiditis.

2 DOSAGE AND ADMINISTRATION Administer Liothyronine Sodium Tablets, USP orally once daily and individual dosage according to patient response and laboratory findings ( 2.1 ) See full prescribing information for recommended dosage for hypothyroidism ( 2.2 ) TSH suppression in well-differentiated thyroid cancer ( 2.3 ) and for thyroid suppression test ( 2.4 ) When switching a patient to Liothyronine Sodium Tablets, USP discontinue levothyroxine therapy and initiate Liothyronine Sodium Tablets, USP at a low dosage. Gradually increase the dose according to the patient's response ( 2.5 ) Adequacy of therapy determined with periodic monitoring of TSH and T3 levels as well as clinical status ( 2.6 ) 2.1 General Principles of Dosing The dose of Liothyronine Sodium Tablets, USP for hypothyroidism or pituitary Thyroid-Stimulating Hormone (TSH) suppression depends on a variety of factors including: the patient's age, body weight, cardiovascular status, concomitant medical conditions (including pregnancy), concomitant medications, co-administered food and the specific nature of the condition being treated [see Dosage and Administration (2.2 , 2.3 , 2.4 ), Warnings and Precautions (5) , and Drug Interactions (7) ] . Dosing must be individualized to account for these factors and dose adjustments made based on periodic assessment of the patient's clinical response and laboratory parameters [see Dosage and Administration (2.4) ]. Administer Liothyronine Sodium Tablets, USP orally once daily. 2.2 Recommended Dosage for Hypothyroidism Adults The recommended starting dosage is 25 mcg orally once daily. Increase the dose by 25 mcg daily every 1 or 2 weeks, if needed. The usual maintenance dose is 25 mcg to 75 mcg once daily. For elderly patients or patients with underlying cardiac disease, start with Liothyronine Sodium Tablets, USP 5 mcg once daily and increase by 5 mcg increments at the recommended intervals. Serum TSH is not a reliable measure of liothyronine sodium dose adequacy in patients with secondary or tertiary hypothyroidism and should not be used to monitor therapy. Use the serum T3 level to monitor adequacy of therapy in this patient population. Pediatric Patients The recommended starting dosage is 5 mcg once daily, with a 5 mcg increase every 3 to 4 days until the desired response is achieved. Infants a few months old may require 20 mcg once daily for maintenance. At 1 year of age, 50 mcg once daily may be required. Above 3 years of age, the full adult dosage may be necessary [see Use in Specific Populations (8.4) ]. Newborns (0 to 3 months) at Risk for Cardiac Failure: Consider a lower starting dose in infants at risk for cardiac failure. Increase the dose as needed based on clinical and laboratory response. Pediatric Patients at Risk for Hyperactivity: To minimize the risk of hyperactivity in pediatric patients, start at one-fourth the recommended full replacement dose, and increase on a weekly basis by one-fourth the full recommended replacement dose until the full recommended replacement dose is reached. Pregnancy Pre-existing Hypothyroidism: Thyroid hormone dose requirements may increase during pregnancy. Measure serum TSH and free-T4 as soon as pregnancy is confirmed and, at minimum, during each trimester of pregnancy. In patients with primary hypothyroidism, maintain serum TSH in the trimester-specific reference range. For patients with serum TSH above the normal trimester-specific range, increase the dose of thyroid hormone and measure TSH every 4 weeks until a stable dose is reached and serum TSH is within the normal trimester-specific range. Reduce thyroid hormone dosage to pre-pregnancy levels immediately after delivery and measure serum TSH levels 4 to 8 weeks postpartum to ensure thyroid hormone dose is appropriate. 2.3 Recommended Dosage for TSH Suppression in Well-Differentiated Thyroid Cancer The dose of Liothyronine Sodium Tablets, USP should target TSH levels within the desired therapeutic range. This may require h …

3 DOSAGE FORMS AND STRENGTHS Tablets available as follows: 5 mcg: white to off white, round, flat faced beveled edge, uncoated tablets, debossed with '582' on one side and plain on the other side. 25 mcg: white to off white, oval shaped, uncoated tablets, debossed with '583' on one side and scored on the other side. 50 mcg: white to off white, capsule shaped, beveled edge, uncoated tablets, debossed with '584' on one side and scored on the other side. Tablets: 5 mcg, 25 mcg, 50 mcg (3)

CONTRAINDICATIONS Thyroid hormone preparations are generally contraindicated in patients with diagnosed but as yet uncorrected adrenal cortical insufficiency, untreated thyrotoxicosis and apparent hypersensitivity to any of their active or extraneous constituents. There is no well-documented evidence from the literature, however, of true allergic or idiosyncratic reactions to thyroid hormone.

6 ADVERSE REACTIONS Adverse reactions associated with liothyronine sodium therapy are primarily those of hyperthyroidism due to therapeutic overdosage [see Warnings and Precautions (5.4) and Overdosage (10) ] . They include the following: General: fatigue, increased appetite, weight loss, heat intolerance, fever, excessive sweating Central nervous system: headache, hyperactivity, nervousness, anxiety, irritability, emotional lability, insomnia Musculoskeletal : tremors, muscle weakness and cramps Cardiovascular: palpitations, tachycardia, arrhythmias, increased pulse and blood pressure, heart failure, angina, myocardial infarction, cardiac arrest Respiratory: dyspnea Gastrointestinal: diarrhea, vomiting, abdominal cramps, elevations in liver function tests Dermatologic: hair loss, flushing Endocrine: decreased bone mineral density Reproductive: menstrual irregularities, impaired fertility Adverse Reactions in Pediatric Patients Pseudotumor cerebri and slipped capital femoral epiphysis have been reported in pediatric patients receiving thyroid replacement therapy. Overtreatment may result in craniosynostosis in infants and premature closure of the epiphyses in pediatric patients with resultant compromised adult height. Hypersensitivity Reactions 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. To report SUSPECTED ADVERSE REACTIONS , contact Sigmapharm Laboratories, LLC, Pharmacovigilance at 1-855-332-0731 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. Most common adverse reactions for Liothyronine Sodium Tablets, USP are primarily those of hyperthyroidism due to therapeutic overdosage: arrhythmias, myocardial infarction, dyspnea, headache, nervousness, irritability, insomnia, tremors, muscle weakness, increased appetite, weight loss, diarrhea, heat intolerance, menstrual irregularities, and skin rash To report SUSPECTED ADVERSE REACTIONS, contact Sigmapharm Laboratories, LLC, Pharmacovigilance at 1-855-332-0731 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

7 DRUG INTERACTIONS See full prescribing information for drugs that affect thyroid hormone pharmacokinetics and metabolism (e.g., absorption, synthesis, secretion, catabolism, protein binding, and target tissue response) and may alter the therapeutic response to liothyronine sodium tablets ( 7 ) 7.1 Drugs Known to Affect Thyroid Hormone Pharmacokinetics Many drugs can exert effects on thyroid hormone pharmacokinetics (e.g. absorption, synthesis, secretion, catabolism, protein binding, and target tissue response) and may alter the therapeutic response to liothyronine sodium tablets (see Tables 1 to 4). Table 1: Drugs That May Decrease T3 Absorption (Hypothyroidism) Potential impact: Concurrent use may reduce the efficacy of liothyronine sodium tablets by binding and delaying or preventing absorption, potentially resulting in hypothyroidism. Drug or Drug Class Effect Bile Acid Sequestrants -Colesevelam -Cholestyramine -Colestipol Ion Exchange Resins -Kayexalate -Sevelamer Bile acid sequestrants and ion exchange resins are known to decrease thyroid hormones absorption. Administer liothyronine sodium tablets at least 4 hours prior to these drugs or monitor thyrotropin-stimulating hormone (TSH) levels. Table 2: Drugs That May Alter Triiodothyronine (T3) Serum Transport Without Affecting Free Thyroxine (FT4) Concentration (Euthyroidism) Drug or Drug Class Effect Clofibrate Estrogen-containing oral contraceptives Estrogens (oral) Heroin / Methadone 5-Fluorouracil Mitotane Tamoxifen These drugs may increase serum thyroxine-binding globulin (TBG) concentration. Androgens / Anabolic Steroids Asparaginase Glucocorticoids Slow-Release Nicotinic Acid These drugs may decrease serum TBG concentration. Salicylates (>2 g/day) Salicylates inhibit binding of T4 and T3 to TBG and transthyretin. An initial increase in serum FT4 is followed by return of FT4 to normal levels with sustained therapeutic serum salicylate concentrations, although total T4 levels may decrease by as much as 30%. Other drugs: Carbamazepine Furosemide (>80 mg IV) Heparin Hydantoins Non-Steroidal Anti- inflammatory Drugs - Fenamates These drugs may cause protein binding site displacement. Furosemide has been shown to inhibit the protein binding of T4 to TBG and albumin, causing an increased free-T4 fraction in serum. Furosemide competes for T4-binding sites on TBG, prealbumin, and albumin, so that a single high dose can acutely lower the total T4 level. Phenytoin and carbamazepine reduce serum protein binding of thyroid hormones, and total and FT4 may be reduced by 20% to 40%, but most patients have normal serum TSH levels and are clinically euthyroid. Closely monitor thyroid hormone parameters. Table 3: Drugs That May Alter Hepatic Metabolism of Thyroid hormones Potential impact: Stimulation of hepatic microsomal drug-metabolizing enzyme activity may cause increased hepatic degradation of thyroid hormones, resulting in increased liothyronine sodium tablets requirements. Drug or Drug Class Effect Phenobarbital Rifampin Phenobarbital has been shown to reduce the response to thyroxine. Phenobarbital increases L-thyroxine metabolism by inducing uridine 5'-diphospho-glucuronosyltransferase (UGT) and leads to a lower T4 serum levels. Changes in thyroid status may occur if barbiturates are added or withdrawn from patients being treated for hypothyroidism. Rifampin has been shown to accelerate the metabolism of thyroid hormones. Table 4: Drugs That May Decrease Conversion of T4 to T3 Potential impact: Administration of these enzyme inhibitors decreases the peripheral conversion of T4 to T3, leading to decreased T3 levels. However, serum T4 levels are usually normal but may occasionally be slightly increased. Drug or Drug Class Effect Beta-adrenergic antagonists (e.g., Propranolol >160 mg/day) In patients treated with large doses of propranolol (>160 mg/day), T3 and T4 levels change, TSH levels remain normal, and patients are clinically euthyroid. Actions of particular beta-adrenerg …

8 USE IN SPECIFIC POPULATIONS Pregnancy may require the use of higher doses of thyroid hormone ( 2.2 , 8.1 ) 8.1 Pregnancy Risk Summary Experience with liothyronine use in pregnant women, including data from post-marketing studies, have not reported increased rates of major birth defects or miscarriages (see Data). There are risks to the mother and fetus associated with untreated hypothyroidism in pregnancy. Since TSH levels may increase during pregnancy, TSH should be monitored and liothyronine sodium tablets dosage adjusted during pregnancy (see Clinical Considerations). There are no animal studies conducted with liothyronine during pregnancy. Liothyronine sodium tablets should not be discontinued during pregnancy and hypothyroidism diagnosed during pregnancy should be promptly treated. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. 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. Clinical Considerations Disease-associated maternal and/or embryo/fetal risk Maternal hypothyroidism during pregnancy is associated with a higher rate of complications, including spontaneous abortion, gestational hypertension, pre-eclampsia, stillbirth, and premature delivery. Untreated maternal hypothyroidism may have an adverse effect on fetal neurocognitive development. Dose adjustments during pregnancy and the postpartum period Pregnancy may increase liothyronine sodium tablets requirements. Serum TSH levels should be monitored and the liothyronine sodium tablets dosage adjusted during pregnancy. Since postpartum TSH levels are similar to preconception values, the liothyronine sodium tablets dosage should return to the pre-pregnancy dose immediately after delivery [see Dosage and Administration ( 2.3 )] . Data Human Data Liothyronine is approved for use as a replacement therapy for hypothyroidism. Data from post-marketing studies have not reported increased rates of fetal malformations, miscarriages, or other adverse maternal or fetal outcomes associated with liothyronine use in pregnant women. 8.2 Lactation Risk Summary Limited published studies report that liothyronine is present in human milk. However, there is insufficient information to determine the effects of liothyronine on the breastfed infant and no available information on the effects of liothyronine on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for liothyronine sodium tablets and any potential adverse effects on the breastfed infant from liothyronine sodium tablets or from the underlying maternal condition. 8.4 Pediatric Use The initial dose of liothyronine sodium tablets varies with age and body weight. Dosing adjustments are based on an assessment of the individual patient’s clinical and laboratory parameters [see Dosage and Administration ( 2.3 , 2.4 )] . In pediatric patients in whom a diagnosis of permanent hypothyroidism has not been established, discontinue thyroid hormone for a trial period, but only after the child is at least 3 years of age. Obtain serum TSH, T4, and T3 levels at the end of the trial period, and use laboratory test results and clinical assessments to guide diagnosis and treatment, if warranted [see Dosage and Administration ( 2.6 )] . Congenital Hypothyroidism [see Dosage and Administration ( 2.2 , 2.6 )] Rapid restoration of normal serum T4 concentrations is essential for preventing the adverse effects of congenital hypothyroidism on intellectual development as well as on overall physical growth and maturation. Therefore, initiate thyroid hormone immediately upon diagnosis. Thyroid hormone is generally continued for life in these patients. Closely monitor infants during the first 2 weeks of thyroid hormone therapy for cardiac overload, arrhythmias, and aspiration from avid sucklin …

12.1 Mechanism of Action Thyroid hormones exert their physiologic actions through control of DNA transcription and protein synthesis. Triiodothyronine (T3) and L-thyroxine (T4) diffuse into the cell nucleus and bind to thyroid receptor proteins attached to DNA. This hormone nuclear receptor complex activates gene transcription and synthesis of messenger RNA and cytoplasmic proteins. The physiological actions of thyroid hormones are produced predominantly by T3, the majority of which (approximately 80%) is derived from T4 by deiodination in peripheral tissues.

DESCRIPTION Thyroid hormone drugs are natural or synthetic preparations containing tetraiodothyronine (T 4 , levothyroxine) sodium or triiodothyronine (T 3 , liothyronine) sodium or both. T 4 and T 3 are produced in the human thyroid gland by the iodination and coupling of the amino acid tyrosine. T 4 contains four iodine atoms and is formed by the coupling of two molecules of diiodotyrosine (DIT). T 3 contains three atoms of iodine and is formed by the coupling of one molecule of DIT with one molecule of monoiodotyrosine (MIT). Both hormones are stored in the thyroid colloid as thyroglobulin. Thyroid hormone preparations belong to two categories: (1) natural hormonal preparations derived from animal thyroid, and (2) synthetic preparations. Natural preparations include desiccated thyroid and thyroglobulin. Desiccated thyroid is derived from domesticated animals that are used for food by man (either beef or hog thyroid), and thyroglobulin is derived from thyroid glands of the hog. The United States Pharmacopeia (USP) has standardized the total iodine content of natural preparations. Thyroid USP contains not less than (NLT) 0.17 percent and not more than (NMT) 0.23 percent iodine, and thyroglobulin contains not less than (NLT) 0.7 percent of organically bound iodine. Iodine content is only an indirect indicator of true hormonal biologic activity. Liothyronine sodium tablets contain liothyronine (L-triiodothyronine or LT 3 ), a synthetic form of a natural thyroid hormone, and is available as the sodium salt. The structural and empirical formulas and molecular weight of liothyronine sodium are given below. Liothyronine Sodium L-Tyrosine, O-(4-hydroxy-3-iodophenyl)-3,5-diiodo-,monosodium salt Twenty-five mcg liothyronine is equivalent to approximately 1 grain of desiccated thyroid or thyroglobulin and 0.1 mg of L-thyroxine. Inactive ingredients consist of calcium sulfate dihydrate, corn starch, gelatin, magnesium stearate and mannitol. image description

OVERDOSAGE Signs and Symptoms - Headache, irritability, nervousness, sweating, arrhythmia (including tachycardia), increased bowel motility and menstrual irregularities. Angina pectoris or congestive heart failure may be induced or aggravated. Shock may also develop. Massive overdosage may result in symptoms resembling thyroid storm. Chronic excessive dosage will produce the signs and symptoms of hyperthyroidism. Treatment Of Overdosage - Dosage should be reduced or therapy temporarily discontinued if signs and symptoms of overdosage appear. Treatment may be reinstituted at a lower dosage. In normal individuals, normal hypothalamic-pituitary-thyroid axis function is restored in 6 to 8 weeks after thyroid suppression. Treatment of acute massive thyroid hormone overdosage is aimed at reducing gastrointestinal absorption of the drugs and counteracting central and peripheral effects, mainly those of increased sympathetic activity. Vomiting may be induced initially if further gastrointestinal absorption can reasonably be prevented and barring contraindications such as coma, convulsions, or loss of the gagging reflex. Treatment is symptomatic and supportive. Oxygen may be administered and ventilation maintained. Cardiac glycosides may be indicated if congestive heart failure develops. Measures to control fever, hypoglycemia, or fluid loss should be instituted if needed. Antiadrenergic agents, particularly propranolol, have been used advantageously in the treatment of increased sympathetic activity. Propranolol may be administered intravenously at a dosage of 1 to 3 mg over a 10-minute period or orally, 80 to 160 mg/day, especially when no contraindications exist for its use.

16 HOW SUPPLIED/STORAGE AND HANDLING Liothyronine sodium tablets, USP are white to off-white, circular, uncoated tablets. They are supplied as follows: Liothyronine sodium tablets, containing 5 mcg liothyronine are debossed ‘589’ on one side and plain on other side. Bottles of 30 with child-resistant closure, NDC 62756-589-83 Bottles of 90 with child-resistant closure, NDC 62756-589-01 Bottles of 100 with child-resistant closure, NDC 62756-589-88 Bottles of 100, NDC 62756-589-08 Bottles of 1000, NDC 62756-589-18 Liothyronine sodium tablets, containing 25 mcg liothyronine are debossed ‘590’ on one side and breakline on other side. Bottles of 30 with child-resistant closure, NDC 62756-590-83 Bottles of 90 with child-resistant closure, NDC 62756-590-01 Bottles of 100 with child-resistant closure, NDC 62756-590-88 Bottles of 100, NDC 62756-590-08 Bottles of 1000, NDC 62756-590-18 Liothyronine sodium tablets, containing 50 mcg liothyronine are debossed ‘591’ on one side and breakline on other side. Bottles of 30 with child-resistant closure, NDC 62756-591-83 Bottles of 90 with child-resistant closure, NDC 62756-591-01 Bottles of 100 with child-resistant closure, NDC 62756-591-88 Bottles of 100, NDC 62756-591-08 Bottles of 1000, NDC 62756-591-18 Store at 20° to 25°C (68° to 77°F); excursions permitted between 15° and 30°C (59° and 86°F) [see USP Controlled Room Temperature].