Alvogen, Inc.

Levothyroxine sodium

Brand

Generic: Levothyroxine sodium

ID: 47781065990

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LEVOTHYROXINE SODIUM 137 MCG TABLET 4778165990

📜 Prescription Required

FORM

Tablet

STRENGTH

137 mcg

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TL;DR — Quick Summary

Key facts from the full medication guide below

RECENT MAJOR CHANGES SECTION WARNING: NOT FOR TREATMENT OF OBESITY OR FOR WEIGHT LOSS 1 INDICATIONS AND USAGE 2 DOSAGE AND ADMINISTRATION 2.1 Important Administration Instructions

🩺What it's for

Hypothyroidism 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.

💊How to take it

Administer once daily, preferably on an empty stomach, one-half to one hour before breakfast. (2.1) Administer at least 4 hours before or after drugs that are known to interfere with absorption. (2.1) Evaluate the need for dose adjustments when regularly administering within one hour of certain foods that may affect absorption. (2.1) Starting dose depends on a variety of factors, including age, body weight, cardiovascular status, and concomitant medications.

ℹ️Common side effects

Overtreatment with levothyroxine may cause an increase in heart rate, cardiac wall thickness, and cardiac contractility and may precipitate angina or arrhythmias, particularly in patients with cardiovascular disease and in elderly patients. Initiate Levothyroxine Sodium Tablets therapy in this population at lower doses than those recommended in younger individuals or in patients without cardiac disease [see Dosage and Administration (2.3) and Use in Specific Populations (8.5)].

⚠️Serious risks

Thyroid hormones, including Levothyroxine Sodium Tablets, 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.

📋Interactions & cautions

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 Levothyroxine Sodium Tablets.

📦Storage & missed dose

How Supplied Levothyroxine Sodium Tablets, in the shape of caplet are supplied as follows (Table 11): Table 11.

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Primary, Secondary, and Tertiary Hypothyroidism in Adults The recommended starting daily dosage of Levothyroxine Sodium Tablets in adults with primary, secondary, or tertiary hypothyroidism is based on age and comorbid cardiac conditions, as described in Table 1. For patients at risk of atrial fibrillation or patients with underlying cardiac disease, start with a lower dosage and titrate the dosage more slowly to avoid exacerbation of cardiac symptoms. Dosage titration is based on serum TSH or free-T4 [see Dosage and Administration (2.2)]. Table 1. Levothyroxine Sodium Tablets Dosing Guidelines for Hypothyroidism in Adults* Patient Population Starting Dosage Dosage Titration Based on Serum TSH or Free-T4 Adults diagnosed with hypothyroidism Full replacement dose is 1.6 mcg/kg/day. Some patients require a lower starting dose. Titrate dosage by 12.5 to 25 mcg increments every 4 to 6 weeks, as needed until the patient is euthyroid. Adults at risk for atrial fibrillation or with underlying cardiac disease Lower starting dose (less than1.6 mcg/kg/day) Titrate dosage every 6 to 8 weeks, as needed until the patient is euthyroid. Geriatric patients Lower starting dose (less than1.6 mcg/kg/day) *Dosages greater than 200 mcg/day are seldom required. An inadequate response to daily dosages greater than 300 mcg/day is rare and may indicate poor compliance, malabsorption, drug interactions, or a combination of these factors [see Dosage and Administration (2.1) and Drug Interactions (7)]. Primary, Secondary, and Tertiary Hypothyroidism in Pediatric Patients The recommended starting daily dosage of Levothyroxine Sodium Tablets in pediatric patients with primary, secondary, or tertiary hypothyroidism is based on body weight and changes with age as described in Table 2. Titrate the dosage (every 2 weeks) as needed based on serum TSH or free-T4 until the patient is euthyroid [see Dosage and Administration (2.2)]. Table 2. Levothyroxine Sodium Tablets Dosing Guidelines for Hypothyroidism in Pediatric Patients Age Starting Daily Dosage Per Kg Body Weight* 0-3 months 10-15 mcg/kg/day 3-6 months 8-10 mcg/kg/day 6-12 months 6-8 mcg/kg/day 1-5 years 5-6 mcg/kg/day 6-12 years 4-5 mcg/kg/day Greater than 12 years but growth and puberty incomplete 2-3 mcg/kg/day Growth and puberty complete 1.6 mcg/kg/day *Adjust dosage based on clinical response and laboratory parameters [see Dosage and Administration (2.4) and Use in Specific Populations (8.4)]. Pediatric Patients from Birth to 3 Months of Age at Risk for Cardiac Failure Start at a lower starting dosage and increase the dosage every 4 to 6 weeks as needed based on clinical and laboratory response. Pediatric Patients at Risk for Hyperactivity To minimize the risk of hyperactivity, start at one-fourth the recommended full replacement dosage, and increase on a weekly basis by one-fourth the full recommended replacement dosage until the full recommended replacement dosage is reached. Hypothyroidism in Pregnant Patients 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. The recommended daily dosage of Levothyroxine Sodium Tablets in pregnant patients is described in Table 3. Table 3. Levothyroxine Sodium Tablets Dosing Guidelines for Hypothyroidism in Pregnant Patients Patient Population Starting Dosage Dose Adjustment and Titration Pre-existing primary hypothyroidism with serum TSH above normal trimester-specific range Pre-pregnancy dosage may increase during pregnancy Increase Levothyroxine Sodium Tablets dosage by 12.5 to 25 mcg per day. Monitor TSH every 4 weeks until a stable dose is reached and serum TSH is within normal trimester-specific range. Reduce Levothyroxine Sodium Tablets dosage to pre-pregnancy levels immediately after delivery. Monitor serum TSH 4 to 8 weeks postpartum. New onset hypothyroidism(TSH 10 mIU per liter) 1.6 mcg/kg/day Monitor serum TSH every 4 weeks and adjust Levothyroxine Sodium Tablets dosage until serum TSH is within normal trimester-specific range. New onset hypothyroidism(TSH < 10 mIU per liter) 1.0 mcg/kg/day TSH Suppression in Well-differentiated Thyroid Cancer in Adult and Pediatric Patients The Levothyroxine Sodium Tablets dosage is based on the target level of TSH suppression for the stage and clinical status of thyroid cancer.

Assess the adequacy of therapy by periodic assessment of laboratory tests and clinical evaluation. Persistent clinical and laboratory evidence of hypothyroidism despite an apparent adequate replacement dose of Levothyroxine Sodium Tablets may be evidence of inadequate absorption, poor compliance, drug interactions, or a combination of these factors. Adults In adult patients with primary hypothyroidism, monitor serum TSH levels after an interval of 6 to 8 weeks after any change in dosage. In patients on a stable and appropriate replacement dosage, evaluate clinical and biochemical response every 6 to 12 months and whenever there is a change in the patient s clinical status. Pediatric Patients In patients with congenital hypothyroidism, assess the adequacy of replacement therapy by measuring both serum TSH and total or free-T4. Monitor TSH and total or free-T4 in pediatric patients as follows: 2 and 4 weeks after the initiation of treatment, 2 weeks after any change in dosage, and then every 3 to 12 months thereafter following dosage stabilization until growth is completed. Poor compliance or abnormal values may necessitate more frequent monitoring. Perform routine clinical examination, including assessment of development, mental and physical growth, and bone maturation, at regular intervals. The general aim of therapy is to normalize the serum TSH level, TSH may not normalize in some patients due to in utero hypothyroidism causing a resetting of pituitary-thyroid feedback. Failure of the serum T4 to increase into the upper half of the normal range within 2 weeks of initiation of Levothyroxine Sodium Tablets therapy and/or of the serum TSH to decrease below 20 units per liter within 4 weeks may indicate the patient is not receiving adequate therapy. Assess compliance, dose of medication administered, and method of administration prior to increasing the dose of Levothyroxine Sodium Tablets [see Warnings and Precautions (5.1) and Use in Specific Populations (8.4)]. Secondary and Tertiary Hypothyroidism Monitor serum free-T4 levels and maintain in the upper half of the normal range in these patients.

Adverse reactions associated with Levothyroxine Sodium Tablets therapy are primarily those of hyperthyroidism due to therapeutic overdosage [see Warnings and Precautions (5) 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, muscle spasm 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, rash Endocrine: decreased bone mineral density Reproductive: menstrual irregularities, impaired fertility Seizures have been reported rarely with the institution of levothyroxine therapy. Adverse Reactions in Pediatric Patients Pseudotumor cerebri and slipped capital femoral epiphysis have been reported in pediatric patients receiving levothyroxine therapy. 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. 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. Hypersensitivity to levothyroxine itself is not known to occur. Adverse reactions associated with Levothyroxine Sodium Tablets therapy are primarily those of hyperthyroidism due to therapeutic overdosage: arrhythmias, myocardial infarction, dyspnea, muscle spasm, headache, nervousness, irritability, insomnia, tremors, muscle weakness, increased appetite, weight loss, diarrhea, heat intolerance, menstrual irregularities, and skin rash. (6) To report SUSPECTED ADVERSE REACTIONS, contact Alvogen, Inc. at 1-866-770-3024 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Many drugs can exert effects on thyroid hormone pharmacokinetics and metabolism (e.g., absorption, synthesis, secretion, catabolism, protein binding, and target tissue response) and may alter the therapeutic response to Levothyroxine Sodium Tablets (Tables 5 to 8). Table 5. Drugs That May Decrease T4 Absorption (Hypothyroidism) Potential impact: Concurrent use may reduce the efficacy of Levothyroxine Sodium Tablets by binding and delaying or preventing absorption, potentially resulting in hypothyroidism. Drug or Drug Class Effect Phosphate Binders(e.g., calcium carbonate, ferrous sulfate, sevelamer, lanthanum) Phosphate binders may bind to levothyroxine. Administer Levothyroxine Sodium Tablets at least 4 hours apart from these agents. Orlistat Monitor patients treated concomitantly with orlistat and Levothyroxine Sodium Tablets for changes in thyroid function. Bile Acid Sequestrants(e.g., colesevelam, cholestyramine, colestipol) Ion Exchange Resins(e.g., Kayexalate) Bile acid sequestrants and ion exchange resins are known to decrease levothyroxine absorption. Administer Levothyroxine Sodium Tablets at least 4 hours prior to these drugs or monitor TSH levels. Proton Pump InhibitorsSucralfate Antacids(e.g., aluminum & magnesium hydroxides, simethicone) Gastric acidity is an essential requirement for adequate absorption of levothyroxine. Sucralfate, antacids and proton pump inhibitors may cause hypochlorhydria, affect intragastric pH, and reduce levothyroxine absorption. Monitor patients appropriately. Table 6. Drugs That May Alter T4 and 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 SteroidsAsparaginase Glucocorticoids Slow-Release Nicotinic Acid These drugs may decrease serum TBG concentration. Potential impact (below): Administration of these agents with Levothyroxine Sodium Tablets results in an initial transient increase in FT4. Continued administration results in a decrease in serum T4 and normal FT4 and TSH concentrations. Salicylates (greater than 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 (greater than 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 increase 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 levothyroxine, and total and free T4 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 7. Drugs That May Alter Hepatic Metabolism of T4 (Hypothyroidism) Potential impact: Stimulation of hepatic microsomal drug-metabolizing enzyme activity may cause increased hepatic degradation of levothyroxine, resulting in increased Levothyroxine 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 levothyroxine. Table 8. 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 greater than 160 mg/day) In patients treated with large doses of propranolol (greater than 160 mg/day), T3 and T4 levels change, TSH levels remain normal, and patients are clinically euthyroid. Actions of particular beta-adrenergic antagonists may be impaired when a hypothyroid patient is converted to the euthyroid state. Glucocorticoids (e.g., Dexamethasone greater than or equal to 4 mg/day) Short-term administration of large doses of glucocorticoids may decrease serum T3 concentrations by 30% with minimal change in serum T4 levels. However, long-term glucocorticoid therapy may result in slightly decreased T3 and T4 levels due to decreased TBG production (See above). Other drugs: Amiodarone Amiodarone inhibits peripheral conversion of levothyroxine (T4) to triiodothyronine (T3) and may cause isolated biochemical changes (increase in serum free-T4, and decreased or normal free-T3) in clinically euthyroid patients.

Absorption Absorption of orally administered T4 from the gastrointestinal tract ranges from 40% to 80%. The majority of the Levothyroxine Sodium Tablets dose is absorbed from the jejunum and upper ileum. The relative bioavailability of Levothyroxine Sodium Tablets, compared to an equal nominal dose of oral levothyroxine sodium solution, is approximately 94%. T4 absorption is increased by fasting, and decreased in malabsorption syndromes and by certain foods such as soybeans. Dietary fiber decreases bioavailability of T4. Absorption may also decrease with age. In addition, many drugs and foods affect T4 absorption [see Drug Interactions (7)]. Distribution Circulating thyroid hormones are greater than 99% bound to plasma proteins, including thyroxine-binding globulin (TBG), thyroxine-binding prealbumin (TBPA), and albumin (TBA), whose capacities and affinities vary for each hormone. 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. Only unbound hormone is metabolically active. 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)]. Elimination Metabolism T4 is slowly eliminated (Table 10). The major pathway of thyroid hormone metabolism is through sequential deiodination. Approximately 80% of circulating T3 is derived from peripheral T4 by monodeiodination. The liver is the major site of degradation for both T4 and T3, with T4 deiodination also occurring at a number of additional sites, including the kidney and other tissues. Approximately 80% of the daily dose of T4 is deiodinated to yield equal amounts of T3 and reverse T3 (rT3). T3 and rT3 are further deiodinated to diiodothyronine. Thyroid hormones are also metabolized via conjugation with glucuronides and sulfates and excreted directly into the bile and gut where they undergo enterohepatic recirculation. Excretion Thyroid hormones are primarily eliminated by the kidneys. A portion of the conjugated hormone reaches the colon unchanged and is eliminated in the feces. Approximately 20% of T4 is eliminated in the stool. Urinary excretion of T4 decreases with age. Table 10. Pharmacokinetic Parameters of Thyroid Hormones in Euthyroid Patients * Includes TBG, TBPA, and TBA ** 3 to 4 days in hyperthyroidism, 9 to 10 days in hypothyroidism Hormone Ratio in Thyroglobulin Biologic Potency t1/2 (days) Protein Binding (%)* Levothyroxine (T4) 10 - 20 1 6-7** 99.96 Liothyronine (T3) 1 4 2 99.5