LEVOTHYROXINE SODIUM- levothyroxine sodium tablet
A-S Medication Solutions
WARNING: NOT FOR TREATMENT OF OBESITY OR FOR WEIGHT LOSS
- Thyroid hormones, including levothyroxine sodium, 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 [see Adverse Reactions (6), Drug Interactions (7.7), and Overdosage (10)].
1 INDICATIONS AND USAGE
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.
Limitations of Use:
- Levothyroxine sodium tablets 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 levothyroxine sodium may induce hyperthyroidism [see Warnings and Precautions (5.1)].
- Levothyroxine sodium tablets are not indicated for treatment of hypothyroidism during the recovery phase of subacute thyroiditis.
2 DOSAGE AND ADMINISTRATION
2.1 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 (6)].
Administer levothyroxine sodium tablets at least 4 hours before or after drugs known to interfere with levothyroxine sodium absorption [see Drug Interactions (7.1)].
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 (7.9) and Clinical Pharmacology (12.3)].
Administer levothyroxine sodium tablets 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. Ensure the patient ingests the full amount of the suspension. Do not store the suspension. Do not administer in foods that decrease absorption of levothyroxine sodium tablets, such as soybean-based infant formula [see Drug Interactions (7.9)].
2.2 Important Considerations for Dosing
The dosage of levothyroxine sodium tablets for hypothyroidism or pituitary 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 (2.3), Warnings and Precautions (5), and Drug Interactions (7)] . Dosing must be individualized to account for these factors and dosage adjustments made based on periodic assessment of the patient’s clinical response and laboratory parameters [see Dosage and Administration (2.4)].
For adult patients with primary hypothyroidism, titrate until the patient is clinically euthyroid and the serum TSH returns to normal [see Dosage and Administration (2.3)].
For secondary or tertiary hypothyroidism, serum TSH is not a reliable measure of levothyroxine sodium dosage adequacy and should not be used to monitor therapy. Use the serum free-T4 level to titrate levothyroxine sodium tablets dosing until the patient is clinically euthyroid and the serum free-T4 level is restored to the upper half of the normal range [see Dosage and Administration (2.3)].
The peak therapeutic effect of a given dose of levothyroxine sodium tablets may not be attained for 4 to 6 weeks.
2.3 Recommended Dosage and Titration
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)].
|*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)].|
|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 than 1.6 mcg/kg/day)||Titrate dosage every 6 to 8 weeks, as needed until the patient is euthyroid.|
|Geriatric patients||Lower starting dose (less than 1.6 mcg/kg/day)|
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)].
Starting Daily Dosage Per Kg Body Weight*
0 to 3 months
10 to 15 mcg/kg/day
3 to 6 months
8 to 10 mcg/kg/day
6 to 12 months
6 to 8 mcg/kg/day
1 to 5 years
5 to 6 mcg/kg/day
6 to 12 years
4 to 5 mcg/kg/day
Greater than 12 years but growth and puberty incomplete
2 to 3 mcg/kg/day
Growth and puberty complete
*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.
|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 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 dosage to pre-pregnancy levels immediately after delivery. Monitor serum TSH 4 to 8 weeks postpartum.|
|New onset hypothyroidism (TSH ≥10 IU per liter)||1.6 mcg/kg/day||Monitor serum TSH every 4 weeks and adjust levothyroxine sodium dosage until serum TSH is within normal trimester-specific range.|
|New onset hypothyroidism (TSH < 10 IU per liter)||1.0 mcg/kg/day|
TSH Suppression in Well-differentiated Thyroid Cancer in Adult and Pediatric Patients
The levothyroxine sodium dosage is based on the target level of TSH suppression for the stage and clinical status of thyroid cancer.
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