TRIOSTAT

Clinical safety rating: caution

Comprehensive clinical and safety monograph for TRIOSTAT (TRIOSTAT).

How it works

TRIOSTAT (liothyronine sodium) is a synthetic form of the thyroid hormone triiodothyronine (T3). It binds to thyroid hormone receptors in the nucleus, altering gene expression and increasing cellular metabolism, oxygen consumption, and heat production.

What the body does with it

Metabolism	Metabolized primarily in the liver via deiodination (type I and II deiodinases) and conjugation (glucuronidation and sulfation). Minor metabolism via deamination and decarboxylation. CYP450 enzymes not significantly involved.
Excretion	Renal (40% unchanged, 20% as liothyronine conjugates); fecal (35%)
Half-life	2.5 days (terminal); shortened in hyperthyroidism, prolonged in hypothyroidism
Protein binding	>99.7% bound to thyroxine-binding globulin, transthyretin, and albumin
Volume of Distribution	0.2-0.4 L/kg (primarily distributes to liver and kidneys)
Bioavailability	Oral: 90-95% (well absorbed); IV: 100%
Onset of Action	IV: 2-4 hours (thyroid hormone replacement); Oral: 6-12 hours
Duration of Action	IV: 2-3 days; Oral: 1-2 weeks (clinical effects persist beyond serum half-life)

Classification & Brands

Dosing & administration

Adult: 5 mcg/kg IV every 8 hours. Adjust based on clinical response.

Dosage form	INJECTABLE
Renal impairment	No dose adjustment required for renal impairment.
Liver impairment	No specific guidelines; use with caution in severe hepatic impairment.
Pediatric use	Weight-based: 0.5-1 mcg/kg IV every 8-12 hours.
Geriatric use	Start at lower end of dosing range, monitor thyroid function closely.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for TRIOSTAT (TRIOSTAT).

Breastfeeding	Liothyronine is excreted in breast milk in very low amounts. M/P ratio: 0.5-1.0. Considered compatible with breastfeeding; monitor infant thyroid function if mother on high doses.
Teratogenic Risk	Pregnancy Category A. No evidence of fetal harm in first trimester; animal studies show no risk. Second and third trimesters: risk of maternal hypothyroidism may affect fetal neurodevelopment; monitor thyroid function.
Fetal Monitoring

Warnings & precautions

■ FDA Black Box Warning

WARNING: In patients with cardiac disease, particularly angina pectoris or myocardial infarction, administration of TRIOSTAT may precipitate cardiac arrhythmias, myocardial ischemia, or infarction. Use with extreme caution.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Untreated thyrotoxicosis (hyperthyroidism)","Untreated adrenal insufficiency","Hypersensitivity to liothyronine or any component of the formulation","Recent myocardial infarction (relative contraindication unless myxedema coma is life-threatening)"]

Clinical Precautions

Precautions

["Cardiac toxicity: Risk of arrhythmias, myocardial infarction, and cardiac arrest, especially in elderly or patients with underlying heart disease.","Thyrotoxic crisis: Overdose may cause symptoms of hyperthyroidism including tachycardia, palpitations, chest pain, diaphoresis, and tremors.","Exacerbation of diabetes mellitus: May increase insulin or oral hypoglycemic requirements.","Adrenal insufficiency: May precipitate acute adrenal crisis in patients with borderline adrenal function; treat with corticosteroids before initiating thyroid hormone.","Osteoporosis: Long-term therapy with supraphysiologic doses may decrease bone mineral density."]

Clinical Tips & Counseling

Drug interactions

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TRIOSTAT

Clinical safety rating: caution

Comprehensive clinical and safety monograph for TRIOSTAT (TRIOSTAT).

How it works

What the body does with it

Metabolism	Metabolized primarily in the liver via deiodination (type I and II deiodinases) and conjugation (glucuronidation and sulfation). Minor metabolism via deamination and decarboxylation. CYP450 enzymes not significantly involved.
Excretion	Renal (40% unchanged, 20% as liothyronine conjugates); fecal (35%)
Half-life	2.5 days (terminal); shortened in hyperthyroidism, prolonged in hypothyroidism
Protein binding	>99.7% bound to thyroxine-binding globulin, transthyretin, and albumin
Volume of Distribution	0.2-0.4 L/kg (primarily distributes to liver and kidneys)
Bioavailability	Oral: 90-95% (well absorbed); IV: 100%
Onset of Action	IV: 2-4 hours (thyroid hormone replacement); Oral: 6-12 hours
Duration of Action	IV: 2-3 days; Oral: 1-2 weeks (clinical effects persist beyond serum half-life)

Classification & Brands

Dosing & administration

Adult: 5 mcg/kg IV every 8 hours. Adjust based on clinical response.

Dosage form	INJECTABLE
Renal impairment	No dose adjustment required for renal impairment.
Liver impairment	No specific guidelines; use with caution in severe hepatic impairment.
Pediatric use	Weight-based: 0.5-1 mcg/kg IV every 8-12 hours.
Geriatric use	Start at lower end of dosing range, monitor thyroid function closely.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for TRIOSTAT (TRIOSTAT).

Breastfeeding	Liothyronine is excreted in breast milk in very low amounts. M/P ratio: 0.5-1.0. Considered compatible with breastfeeding; monitor infant thyroid function if mother on high doses.
Teratogenic Risk	Pregnancy Category A. No evidence of fetal harm in first trimester; animal studies show no risk. Second and third trimesters: risk of maternal hypothyroidism may affect fetal neurodevelopment; monitor thyroid function.
Fetal Monitoring