Synthroid

SYNTHROID- levothyroxine sodium tablet
Avera McKennan Hospital

WARNING: NOT FOR TREATMENT OF OBESITY OR FOR WEIGHT LOSS

  • Thyroid hormones, including SYNTHROID, 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

Hypothyroidism

SYNTHROID is indicated as a replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism.

Pituitary Thyrotropin (Thyroid‑Stimulating Hormone, TSH) Suppression

SYNTHROID is indicated as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer.

  • Limitations of Use:
  • SYNTHROID is 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 SYNTHROID may induce hyperthyroidism [see Warnings and Precautions (5.4)].
  • SYNTHROID is not indicated for treatment of hypothyroidism during the recovery phase of subacute thyroiditis.

2 DOSAGE AND ADMINISTRATION

2.1 General Administration Information

Administer SYNTHROID as a single daily dose, on an empty stomach, one-half to one hour before breakfast.

Administer SYNTHROID at least 4 hours before or after drugs known to interfere with SYNTHROID absorption [see Drug Interactions (7.1)].

Evaluate the need for dose adjustments when regularly administering within one hour of certain foods that may affect SYNTHROID absorption [see Drug Interactions (7.9) and Clinical Pharmacology (12.3)].

Administer SYNTHROID to infants and children who cannot swallow intact tablets by crushing the tablet, suspending the freshly crushed tablet in a small amount (5 to 10 mL or 1 to 2 teaspoons) of water and immediately administering the suspension by spoon or dropper. Do not store the suspension. Do not administer in foods that decrease absorption of SYNTHROID, such as soybean-based infant formula [see Drug Interactions (7.9)].

2.2 General Principles of Dosing

The dose of SYNTHROID 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 dose adjustments made based on periodic assessment of the patient’s clinical response and laboratory parameters [see Dosage and Administration (2.4)].

The peak therapeutic effect of a given dose of SYNTHROID may not be attained for 4 to 6 weeks.

2.3 Dosing in Specific Patient Populations

Primary Hypothyroidism in Adults and in Adolescents in Whom Growth and Puberty are Complete

Start SYNTHROID at the full replacement dose in otherwise healthy, non-elderly individuals who have been hypothyroid for only a short time (such as a few months). The average full replacement dose of SYNTHROID is approximately 1.6 mcg per kg per day (for example: 100 to 125 mcg per day for a 70 kg adult).

Adjust the dose by 12.5 to 25 mcg increments every 4 to 6 weeks until the patient is clinically euthyroid and the serum TSH returns to normal. Doses greater than 200 mcg per day are seldom required. An inadequate response to daily doses of greater than 300 mcg per day is rare and may indicate poor compliance, malabsorption, drug interactions, or a combination of these factors.

For elderly patients or patients with underlying cardiac disease, start with a dose of 12.5 to 25 mcg per day. Increase the dose every 6 to 8 weeks, as needed until the patient is clinically euthyroid and the serum TSH returns to normal. The full replacement dose of SYNTHROID may be less than 1 mcg per kg per day in elderly patients.

In patients with severe longstanding hypothyroidism, start with a dose of 12.5 to 25 mcg per day. Adjust the dose in 12.5 to 25 mcg increments every 2 to 4 weeks until the patient is clinically euthyroid and the serum TSH level is normalized.

Secondary or Tertiary Hypothyroidism

Start SYNTHROID at the full replacement dose in otherwise healthy, non-elderly individuals. Start with a lower dose in elderly patients, patients with underlying cardiovascular disease or patients with severe longstanding hypothyroidism as described above. Serum TSH is not a reliable measure of SYNTHROID dose adequacy in patients with secondary or tertiary hypothyroidism and should not be used to monitor therapy. Use the serum free-T4 level to monitor adequacy of therapy in this patient population. Titrate SYNTHROID dosing per above instructions until the patient is clinically euthyroid and the serum free-T4 level is restored to the upper half of the normal range.

Pediatric Dosage — Congenital or Acquired Hypothyroidism

The recommended daily dose of SYNTHROID in pediatric patients with hypothyroidism is based on body weight and changes with age as described in Table 1. Start SYNTHROID at the full daily dose in most pediatric patients. Start at a lower starting dose in newborns (0-3 months) at risk for cardiac failure and in children at risk for hyperactivity (see below). Monitor for clinical and laboratory response [see Dosage and Administration (2.4)].

Table 1. SYNTHROID Dosing Guidelines for Pediatric Hypothyroidism
AGE Daily Dose Per Kg Body Weighta
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
  1. The dose should be adjusted based on clinical response and laboratory parameters [see Dosage and Administration (2.4) and Use in Specific Populations (8.4)].

Newborns (0-3 months) at risk for cardiac failure: Consider a lower starting dose in newborns at risk for cardiac failure.

Increase the dose every 4 to 6 weeks as needed based on clinical and laboratory response.

Children at risk for hyperactivity: To minimize the risk of hyperactivity in children, 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.

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