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CYTOMEL® (liothyronine sodium) Highlights

HIGHLIGHTS OF PRESCRIBING INFORMATION

These highlights do not include all the information needed to use CYTOMEL safely and effectively. See full prescribing information for CYTOMEL.

CYTOMEL® (liothyronine sodium) tablets, for oral use
Initial U.S. Approval: 1956

WARNING: NOT FOR TREATMENT OF OBESITY OR FOR WEIGHT LOSS

See full prescribing information for complete boxed warning.

  • Thyroid hormones, including CYTOMEL, should not be used for the treatment of obesity or for weight loss.
  • Doses beyond the range of daily hormonal requirements may produce serious or even life-threatening manifestations of toxicity (6, 7.7, 10).

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

INDICATIONS AND USAGE

CYTOMEL 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 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)

DOSAGE AND ADMINISTRATION

  • Administer CYTOMEL 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 CYTOMEL, discontinue levothyroxine therapy and initiate CYTOMEL 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)

DOSAGE FORMS AND STRENGTHS

Tablets: 5 mcg, 25 mcg, 50 mcg (3)

CONTRAINDICATIONS

Uncorrected adrenal cortical insufficiency (4)

WARNINGS AND PRECAUTIONS

  • Cardiac adverse reactions in the elderly and in patients with underlying cardiovascular disease: Initiate CYTOMEL at less than the full replacement dose because of the increased risk of cardiac adverse reactions, including atrial fibrillation (2.3, 5.1, 8.5)
  • Myxedema coma: Do not use oral thyroid hormone drug products to treat myxedema coma. (5.2)
  • Acute adrenal crisis in patients with concomitant adrenal insufficiency: Treat with replacement glucocorticoids prior to initiation of CYTOMEL treatment (5.3)
  • Prevention of hyperthyroidism or incomplete treatment of hypothyroidism: Proper dose titration and careful monitoring is critical to prevent the persistence of hypothyroidism or the development of hyperthyroidism. (5.4)
  • Worsening of diabetic control: Therapy in patients with diabetes mellitus may worsen glycemic control and result in increased antidiabetic agent or insulin requirements. Carefully monitor glycemic control after starting, changing, or discontinuing thyroid hormone therapy (5.5)
  • Decreased bone mineral density associated with thyroid hormone over-replacement: Over-replacement can increase bone resorption and decrease bone mineral density. Give the lowest effective dose (5.6)

ADVERSE REACTIONS

Most common adverse reactions for CYTOMEL 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 (6)


To report SUSPECTED ADVERSE REACTIONS, contact Pfizer, Inc. at 1-800-438-1985 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

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 CYTOMEL (7)

USE IN SPECIFIC POPULATIONS

Pregnancy may require the use of higher doses of thyroid hormone (2.2, 8.1)

See 17 for PATIENT COUNSELING INFORMATION.

Revised: 7/2019

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