Classes
DEA Class; Rx
Common Brand Names; Thyrolar
- Thyroid Products
Description
Oral mixture of 2 synthetic thyroid hormones: T4 (levothyroxine) and T3 (liothyronine), in a 4-to-1 ratio by weight, respectively
Used for hypothyroidism of almost any etiology, including congenital hypothyroidism (cretinism) and myxedema in adults and pediatric patients
Levothyroxine is the preferred replacement therapy for routine use; combination of T3 an T4 therapy may be useful in select patients, such as those with symptoms despite stabilization of a dose for T4 replacement
A “Liotrix-1” synthetic tablet is roughly comparable to a porcine thyroid USP 1 grain (60 mg) tablet (e.g., Armour Thyroid)
Indications
Contraindications
Hypersensitivity to thyroid hormone
Acute MI uncomplicated by hypothyroidism, untreated thyrotoxicosis, untreated adrenal insufficiency
Treatment of obesity
Adverse Effects
Arrhythmias
Increased blood pressure
Chest pain
Palpitation
Anxiety
Headache
Urticaria
Changes in menstrual cycle
Insomnia
Hyperhydrosis pruritus
Tachycardia
Nervousness
Tremor
Cramps
Increased appetite
Weight loss
Diarrhea
Warnings
Caution in angina, cardiovascular disease, HTN, endocrine disorders, elderly
Use caution in patients with adrenal insufficiency (symptoms may become exagerated or aggravated)
Euthroid withdrawn from U.S. market
Use caution in patients with myxedema (symptoms may become exagerated or aggravated)
No advantage over levothyroxine & may do more harm (T3 overdosage) than good
Not for the treatment of female infertility in euthyroid patients
Pregnancy and Lactation
Pregnancy Category: A
Lactation: Small amount excreted into breast milk, use caution
Maximum Dosage
Liotrix has a narrow therapeutic index; dosage must be individualized.
Doses greater than Thyrolar-2 (100 mcg T4 and 25 mcg T3)/day PO rarely needed.
Doses greater than Thyrolar-2 (100 mcg T4 and 25 mcg T3)/day PO rarely needed.
Adolescents in whom growth and puberty are complete: Doses greater than Thyrolar-2 (100 mcg T4 and 25 mcg T3)/day PO rarely needed.
Individualize dosage.
How supplied
Liotrix T3;T4
Each 60 mg tablet will replace approximately 60-65 mg (1 grain) of desicated thyroid
Liothyronine sodium (T3) is approximately 4 times as potent as levothyroxine (T4)
tablet, T3/T4
- Thyrolar 1/4 (15mg): 3.1/12.5mcg
- Thyrolar 1/2 (30mg): 6.25/25mcg
- Thyrolar 1 (60mg): 12.5/50mcg
- Thyrolar 2 (120mg): 25/100mcg
- Thyrolar 3 (180mg): 37.5/150mcg