Levothyroxine

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. Pituitary Thyrotropin (Thyroid‑Stimulating Hormone, TSH) Suppression Levothyroxine sodium tablets are 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. …

• Administer once daily, preferably on an empty stomach, one-half to one hour before breakfast with a full glass of water
• 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
• Advise patients to stop biotin and biotin-containing supplements at least 2 days before assessing TSH and/or T4 levels
• Starting dose depends on a variety of factors, including age, body weight, cardiovascular status, and concomitant medications
• Peak therapeutic effect may not be attained for 4 to 6 weeks
• See full prescribing information for dosing in specific patient populations
• Adequacy of therapy determined with periodic monitoring of TSH and/or T4 as well as clinical status
• Important Administration Instructions Administer levothyroxine sodium tablets as a single daily dose, on an empty stomach, one-half to one hour before breakfast with a full glass of water to avoid choking or gagging [see Adverse Reactions ]
• Administer levothyroxine sodium tablets at least 4 hours before or after drugs known to interfere with levothyroxine sodium absorption [see Drug Interactions ]
• Evaluate the need for dosage adjustments when regularly administering within one hour of certain foods that may affect levothyroxine sodium tablets absorption [see Dosage and Administration (2.2 and 2.3) , Drug Interactions , and Clinical Pharmacology ]. …

All tablets having functional scoring Levothyroxine sodium tablets USP are available as follows (Table 4): Table 4: Levothyroxine Sodium Tablet Strengths and Identifying Features Tablet Strength Tablet Description 25 mcg Round shaped, Orange colored, uncoated tablets, break line on both side and debossed with "P" and "1" on one side and plain on other side. …

• Levothyroxine sodium is indicated in patients from birth to less than 17 years of age: As a replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism
• As an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer
• 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. …

Because of the increased prevalence of cardiovascular disease among the elderly, initiate levothyroxine sodium at less than the full replacement dose [see Dosage and Administration (2.3) and Warnings and Precautions (5.2) ] . Atrial arrhythmias can occur in elderly patients. Atrial fibrillation is the most common of the arrhythmias observed with levothyroxine overtreatment in the elderly.

• Inform the patient of the following information to aid in the safe and effective use of Levothyroxine sodium tablets: Dosing and Administration Instruct patients to take levothyroxine sodium tablets only as directed by their healthcare provider
• Instruct patients to take levothyroxine sodium tablets as a single dose, preferably on an empty stomach, one-half to one hour before breakfast with a full glass of water to avoid choking or gagging
• Inform patients that agents such as iron and calcium supplements and antacids can decrease the absorption of levothyroxine
• Instruct patients not to take levothyroxine sodium tablets within 4 hours of these agents. …

• Levothyroxine sodium tablets are contraindicated in patients with uncorrected adrenal insufficiency [see Warnings and Precautions ]
• Uncorrected adrenal insufficiency

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. (7) 7.1 Drugs Known to Affect Thyroid Hormone Pharmacokinetics 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 (Tables 5 to 8). Table 5. …

Serious risks related to overtreatment or undertreatment with levothyroxine sodium tablets: Titrate the dose of levothyroxine sodium carefully and monitor response to titration. (5.1) Cardiac adverse reactions in the elderly and in patients with underlying cardiovascular disease: Initiate levothyroxine sodium at less than the full replacement dose because of the increased risk of cardiac adverse reactions, including atrial fibrillation. (2.3 , 5.2 , 8.5) Myxedema coma: Do not use oral thyroid hormone drug products to treat myxedema coma. …

Adverse reactions associated with levothyroxine sodium 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, abdomi …

8.1 Pregnancy Risk Summary The clinical experience, including data from postmarketing studies, in pregnant women treated with oral levothyroxine to maintain euthyroid state have not reported increased rates of major birth defects, miscarriages, or other adverse maternal or fetal outcomes. There are risks to the mother and fetus associated with untreated hypothyroidism in pregnancy. …

The signs and symptoms of overdosage are those of hyperthyroidism [see Warnings and Precautions (5) and Adverse Reactions (6) ] . In addition, confusion and disorientation may occur. Cerebral embolism, shock, coma, and death have been reported. Seizures occurred in a 3-year-old child ingesting 3.6 mg of levothyroxine. Symptoms may not necessarily be evident or may not appear until several days after ingestion of levothyroxine sodium. Reduce the levothyroxine sodium dosage or discontinue temporarily if signs or symptoms of overdosage occur. …

تناولها عندما تتذكر، إلا إذا اقترب موعد الجرعة التالية. عندها تخطَّ الجرعة المنسية. لا تتناول جرعتين معًا أبدًا للتعويض. راجع النشرة، فبعض الأدوية مختلفة.