Also found in: Dictionary, Thesaurus.
liothyronine sodium (T3)
Cytomel, Tertroxin (UK), Triostat
Pharmacologic class: Synthetic thyroxine hormone
Therapeutic class: Thyroid hormone replacement
Pregnancy risk category A
FDA Box Warning
• Drug has been used (alone or with other agents) to treat obesity. In euthyroid patients, doses within range of daily hormonal requirements are ineffective for weight loss. Larger doses may cause serious or life-threatening toxicity, particularly when given with sympathomimetic amines (such as those used for anorectic effects).
Synthetic form of triiodothyronine (T3). Regulates cell growth and differentiation; increases metabolism of lipids, proteins, and carbohydrates; and enhances aerobic mitochondrial function. Also reduces tissue lactic acidosis.
Injection: 10 mcg/ml in 1-ml vials
Tablets: 5 mcg, 25 mcg, 50 mcg
⊘Indications and dosages
➣ Thyroid hormone replacement in mild hypothyroidism
Adults: All dosages individualized. Initially, 25 mcg P.O. daily; may increase in increments of 12.5 to 25 mcg/day q 1 to 2 weeks. Usual maintenance dosage is 25 to 75 mcg P.O. daily.
Adults: All dosages individualized. Initially, 5 mcg P.O. daily; increase in increments of 5 to 10 mcg/day q 1 to 2 weeks, up to 25 mcg/day. If response still isn't adequate, increase by 5 mcg to 25 mcg P.O. daily q 1 to 2 weeks until desired response occurs. Usual maintenance dosage is 50 to 100 mcg/day P.O.
➣ Myxedema coma
Adults: Initially, 25 to 50 mcg I.V.; after 4 hours, reassess patient's need for subsequent doses (up to 65 mcg in 24 hours). In cardiovascular disease, initial dosage is 10 to 20 mcg I.V.
➣ Simple goiter
Adults: All dosages individualized. Initially, 5 mcg P.O. daily. Increase by 5 to 10 mcg/day q 1 to 2 weeks, up to 25 mcg/day; then increase by 12.5 to 25 mcg P.O. daily q week until desired effect occurs. Usual maintenance dosage is 75 mcg P.O. daily.
Children or elderly adults: Initially, 5 mcg P.O once daily. Increase by 5 mcg q 1 to 2 weeks until desired effect occurs.
➣ T3 suppression test to distinguish hyperthyroidism from thyroid gland autonomy
Adults: 75 to 100 mcg P.O. daily for 7 days in conjunction with radioactive iodine
• Severe, long-standing hypothyroidism
• Cardiovascular disease
• Psychosis or agitation
• Elderly patients
• Hypersensitivity to drug or its components
• Acute myocardial infarction
• Untreated thyrotoxicosis
• Uncorrected adrenal insufficiency and coexisting hypothyroidism
• Artificial rewarming (I.V. form only)
Use cautiously in:
• cardiovascular disease, severe renal insufficiency, uncorrected adrenocortical disorders, diabetes mellitus
• elderly patients
• pregnant or breastfeeding patients.
• Know that all dosages are highly individualized.
• Administer single oral dose in morning with or without food.
• Injectable form is for I.V. use only. Don't give I.M.
• Infuse each 10-mcg dose over 1 minute.
• Give repeat I.V. doses more than 4 hours but less than 12 hours apart.
• Be aware that in T3 suppression test, radioactive iodine (131I) is given before and after 7-day liothyronine course.
CNS: insomnia, irritability, nervousness, headache
CV: tachycardia, angina pectoris, hypotension, hypertension, increased cardiac output, arrhythmias, cardiovascular collapse
GI: vomiting, diarrhea, cramps
GU: menstrual irregularities
Metabolic: hyperthyroidism, hyperglycemia
Musculoskeletal: accelerated bone maturation (in children), decreased bone density (with long-term use in women)
Skin: alopecia (in children), diaphoresis
Other: weight loss, heat intolerance
Drug-drug.Anabolic steroids, antithyroid drugs, asparaginase, barbiturates, carbamazepine, chloral hydrate, clofibrate, corticosteroids, danazol, estrogens, fluorouracil, heparin (with I.V. use), lithium, methadone, mitotane, oxyphenbutazone, perphenazine, phenylbutazone, phenytoin, propranolol, salicylates (large doses), sulfonylureas: altered thyroid function test results
Anticoagulants: increased anticoagulant action
Beta-adrenergic blockers (selected): impaired beta blocker action
Cardiac glycosides: decreased cardiac glycoside blood level
Cholestyramine, colestipol: liothyronine inefficacy
Theophyllines: decreased theophylline clearance
Drug-diagnostic tests.Thyroid function tests: altered values
Drug-food.Foods high in iron or fiber, soybeans: decreased drug absorption
☞ Monitor for evidence of overdose, including signs and symptoms of hyperthyroidism (weight loss, cardiac symptoms, and abdominal cramps).
• In patients with Addison's disease or diabetes mellitus, assess for evidence that these conditions are worsening. In diabetic patients, also monitor blood glucose level.
• Monitor vital signs and ECG routinely.
• Check thyroid and liver function tests.
• Teach patient to take in morning with or without food.
• Explain that patient may require lifelong therapy and will need to undergo regular blood testing.
• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
• Inform parents that hair loss may occur in children during first few months but that this effect is usually transient.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and foods mentioned above.
Pharmacologic: thyroid preparations
- Promote gluconeogenesis,
- Increase utilization and mobilization of glycogen stores,
- Stimulate protein synthesis,
- Promote cell growth and differentiation,
- Aid in the development of the brain and CNS.
|Liothyronine PO||unknown||24–72 hr||72 hr|
Adverse Reactions/Side EffectsUsually only seen when excessive doses cause iatrogenic hyperthyroidism
Central nervous system
- angina pectoris
- abdominal cramps
- menstrual irregularities
- weight loss
- heat intolerance
- accelerated bone maturation in children
Drug-Drug interactionBile acid sequestrants ↓ absorption of orally administered thyroid preparations.Alters the effectiveness of warfarin (INR will ↑ with thyroid hormone supplementation).May ↑ requirement for insulin or oral hypoglycemic agents in diabetics.Concurrent estrogen therapy may ↑ thyroid replacement requirements.↑ cardiovascular effects with adrenergics (sympathomimetics).
Availability (generic available)
- Assess apical pulse and BP prior to and periodically during therapy. Assess for tachyarrhythmias and chest pain.
- Children: Monitor height, weight, and psychomotor development.
- Lab Test Considerations: Monitor thyroid function studies prior to and during therapy.
Overdose is manifested as hyperthyroidism (tachycardia, chest pain, nervousness, insomnia, diaphoresis, tremors, weight loss). Usual treatment is to withhold dose for 2–6 days. Acute overdose is treated by induction of emesis or gastric lavage, followed by activated charcoal. Sympathetic overstimulation may be controlled by antiadrenergic drugs (beta blockers), such as propranolol. Oxygen and supportive measures to control symptoms are also used.
- Monitor blood and urine glucose in diabetic patients. Insulin or oral hypoglycemic dose may need to be increased.
Potential Nursing DiagnosesDeficient knowledge, related to medication regimen (Patient/Family Teaching)
- Oral: Administer as a single dose, preferably before breakfast to prevent insomnia.
- Initial dose is low, especially in geriatric and cardiac patients. Dose is increased gradually, based on thyroid function tests. Side effects occur more rapidly with liothyronine because of its rapid onset of effect.
- For patients with difficulty swallowing, tablets can be crushed and placed in 5–10 mL of water and administered immediately via dropper or spoon; do not store suspension.
- pH: No Data.
- Intravenous: Liothyronine injection is for IV use only. Do not give IM or subcut. Administer doses at least 4 hr and not more than 12 hr apart. Base doses on continuous monitoring of patient and response to therapy.
- Resume PO therapy as soon as patient is stable and able to take PO medication. When switching to PO therapy, discontinue IV liothyronine and initiate PO at low dose, increasing gradually according to patient’s response.
- May be administered undiluted.
- Rate: Administer as a bolus.
- Instruct patient to take medication as directed at the same time each day. Take missed doses as soon as remembered unless almost time for next dose. If more than 2–3 doses are missed, notify health care professional. Do not discontinue without consulting health care professional.
- Explain to patient that medication does not cure hypothyroidism; it provides a thyroid hormone supplement. Therapy is lifelong.
- Advise patient to notify health care professional if headache, nervousness, diarrhea, excessive sweating, heat intolerance, chest pain, increased pulse rate, palpitations, weight loss >2 lb/wk, or any unusual symptoms occur.
- Caution patient to avoid taking other medications concurrently with thyroid preparations unless instructed by health care professional.
- Instruct patient to inform health care professionals of thyroid therapy.
- Emphasize importance of follow-up exams to monitor effectiveness of therapy. Thyroid function tests are performed at least yearly.
- Pediatric: Discuss with parents the need for routine follow-up studies to ensure correct development. Inform patient that partial hair loss may be experienced by children on thyroid therapy. This is usually temporary.
- Resolution of symptoms of hypothyroidism and normalization of hormone levels.