Cytomel

Cytomel is an FDA-registered drug product whose active ingredient is LIOTHYRONINE SODIUM. It is labelled by Pfizer Laboratories Div Pfizer Inc taken by oral and marketed as a human prescription drug product. Identifiers on file: NDC 60793-115, application NDA010379, label effective 20260518. It is one of 12 FDA drug label records sharing the active ingredient LIOTHYRONINE SODIUM. This page reproduces the FDA-approved label text so you can check what a product is, who makes it and how it is supplied before discussing it with a pharmacist or prescriber.

Across FDA labelling, products containing LIOTHYRONINE SODIUM are most often described in connection with: cytomel indicated, primary thyroidal, secondary pituitary, tertiary hypothalamic, congenital acquired, thyroid-stimulating hormone, tsh suppression, adjunct surgery. Wording differs between labels, and the full indications section on this page takes precedence when it is present.

1 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 ) 1.1 Hypothyroidism CYTOMEL is indicated as a replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism. 1.2 Pituitary Thyroid-Stimulating Hormone (TSH) Suppression CYTOMEL is indicated as an adjunct to surgery and radioiodine therapy in the management of well-differentiated thyroid cancer . 1.3 Thyroid Suppression Test CYTOMEL is indicated as a diagnostic agent in suppression tests to differentiate suspected mild hyperthyroidism or thyroid gland autonomy. Limitations of Use • CYTOMEL 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 CYTOMEL may induce hyperthyroidism [see Warnings and Precautions (5.4) ] . • CYTOMEL is not indicated for treatment of hypothyroidism during the recovery phase of subacute thyroiditis.

2 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 ) 2.1 General Principles of Dosing The dose of CYTOMEL 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 (2.2 , 2.3 , 2.4) , 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) ] . Administer CYTOMEL tablets orally once daily. 2.2 Recommended Dosage for Hypothyroidism Adults The recommended starting dosage is 25 mcg orally once daily. Increase the dose by 25 mcg daily every 1 or 2 weeks, if needed. The usual maintenance dose is 25 mcg to 75 mcg once daily. For elderly patients or patients with underlying cardiac disease, start with CYTOMEL 5 mcg once daily and increase by 5 mcg increments at the recommended intervals. Serum TSH is not a reliable measure of CYTOMEL dose adequacy in patients with secondary or tertiary hypothyroidism and should not be used to monitor therapy. Use the serum T3 level to monitor adequacy of therapy in this patient population. Pediatric Patients The recommended starting dosage is 5 mcg once daily, with a 5 mcg increase every 3 to 4 days until the desired response is achieved. Infants a few months old may require 20 mcg once daily for maintenance. At 1 year of age, 50 mcg once daily may be required. Above 3 years of age, the full adult dosage may be necessary [see Use in Specific Populations (8.4) ]. Newborns (0 to 3 months) at Risk for Cardiac Failure: Consider a lower starting dose in infants at risk for cardiac failure. Increase the dose as needed based on clinical and laboratory response. Pediatric Patients at Risk for Hyperactivity: To minimize the risk of hyperactivity in pediatric patients, 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. Pregnancy Pre-existing Hypothyroidism: Thyroid hormone dose requirements may increase during pregnancy. Measure serum TSH and free-T4 as soon as pregnancy is confirmed and, at minimum, during each trimester of pregnancy. In patients with primary hypothyroidism, maintain serum TSH in the trimester-specific reference range. For patients with serum TSH above the normal trimester-specific range, increase the dose of thyroid hormone and measure TSH every 4 weeks until a stable dose is reached and serum TSH is within the normal trimester-specific range. Reduce thyroid hormone dosage to pre-pregnancy levels immediately after delivery and measure serum TSH levels 4 to 8 weeks postpartum to ensure thyroid hormone dose is appropriate. 2.3 Recommended Dosage for TSH Suppression in Well-Differentiated Thyroid Cancer The dose of CYTOMEL should target TSH levels within the desired therapeutic range. This may require higher doses, depending on the target level for TSH suppression. 2.4 Recommended Dosage for Thyroid Suppression Test The recommended dose is 75 mcg to 100 mcg daily for 7 days, with radioactive iodine uptake being determined before and after the 7 day administration of CYTOMEL. If thyroid function is normal, the radioiodine uptake will drop significantly after treatment. A 50% or greater suppression of uptake indicates a normal thyroid-pituitary axis. 2.5 Switching from Levothyroxine to CYTOMEL CYTOMEL has a rapid onset of action and residual effects of the other thyroid preparation may persist for the first several weeks after initiating CYTOMEL therapy. When switching a patient to CYTOMEL, discontinue levothyroxine therapy and initiate CYTOMEL at a low dosage. Gradually increase the CYTOMEL dose according to the patient's response. 2.6 Monitoring TSH and Triiodothyronine (T3) Levels 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 CYTOMEL 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 periodically after initiation of the therapy or any change in dose. To check the immediate response to therapy before the TSH has had a chance to respond or if your patient's status needs to be assessed prior to that point, measurement of total T3 would be most appropriate. In patients on a stable and appropriate replacement dose, evaluate clinical and biochemical response every 6 to 12 months and whenever there is a change in the patient's clinical status. Pediatrics In pediatric patients with hypothyroidism, assess the adequacy of replacement therapy by measuring serum TSH and T3 levels. For pediatric patients three years of age and older, the recommended monitoring is every 3 to 12 months thereafter, following dose stabilization until growth and puberty are 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. While 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 TSH to decrease below 20 IU per liter after initiation of CYTOMEL therapy may indicate the child is not receiving adequate therapy. Assess compliance, dose of medication administered, and method of administration prior to increasing the dose of CYTOMEL [see Warnings and Precautions (5.1) and Use in Specific Populations (8.4) ] . Secondary and Tertiary Hypothyroidism Monitor serum T3 levels and maintain in the normal range.

4 CONTRAINDICATIONS CYTOMEL is contraindicated in patients with uncorrected adrenal insufficiency [see Warnings and Precautions (5.3) ] . Uncorrected adrenal cortical insufficiency ( 4 )

6 ADVERSE REACTIONS Adverse reactions associated with CYTOMEL therapy are primarily those of hyperthyroidism due to therapeutic overdosage [see Warnings and Precautions (5.4) 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 and cramps 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 Endocrine : decreased bone mineral density Reproductive : menstrual irregularities, impaired fertility 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 . Adverse Reactions in Pediatric Patients Pseudotumor cerebri and slipped capital femoral epiphysis have been reported in pediatric patients receiving thyroid replacement therapy. Overtreatment may result in craniosynostosis in infants and premature closure of the epiphyses in pediatric patients 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.

FDA lists 12 drug label records with LIOTHYRONINE SODIUM as the active ingredient. The most common dosage forms and the manufacturers with the most records are summarised below; strengths, pack sizes and inactive ingredients can still differ between apparently similar products.

What is Cytomel used for?
1 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 ( …

Who makes Cytomel?
Pfizer Laboratories Div Pfizer Inc is the labeler of record for Cytomel. 12 FDA label records share the active ingredient LIOTHYRONINE SODIUM, so generic and branded versions may come from different companies; the manufacturer named on your pack is the one that matters for any enquiry.

What form does Cytomel come in?
administered by oral. Strengths and pack sizes vary by label, so compare the NDC on your pack with the identifier listed on this page.

Is Cytomel prescription or over-the-counter?
The FDA label for this product is recorded as human prescription drug. Marketing status can differ between strengths and countries, so check the dispensing rules where you live.

Are there other products containing LIOTHYRONINE SODIUM?
Yes. 12 FDA drug label records list LIOTHYRONINE SODIUM as the active ingredient. Products with the same active ingredient can usually be substituted only when a prescriber or pharmacist confirms it is appropriate.

Has Cytomel been recalled?
No FDA recall record in our database matches this product name or manufacturer. Recall data is updated periodically, so a very recent notice may not appear here yet.

Where does this information come from?
All content is reproduced from FDA Structured Product Labelling data via openFDA. It is provided for identification and reference only and is not medical advice.