Dosing & Uses
Dosage Forms & Strengths
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
Hypothyroidism
1 tab of Thyrolar 1/2 daily; follow with increments of 1 tab of Thyrolar 1/4 q2-3wk
Lower starting dose of 1 tab recommended in long-standing myxedema, especially if cardiovascular impairment suspected where extreme caution recommended
Maintenance: 1 tab Thyrolar 1 to 1 tab Thyrolar 2 per day; failure to respond to tab Thyrolar 3 may suggest lack of compliance or malabsorption
Adjust dose within the first 4 weeks of therapy after proper clinical laboratory evaluations where serum levels of T4 bound and free TSH are measured
Administer before breakfast
Dosage Forms & Strengths
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
Congenital Hypothyroidism
0-6 months: 3.1/12.5 to 6.25/25 PO;
6-12 months: 6.25/25 to 9.35/37.5 PO;
1-5 years: 9.35/37.5-12.5/50 mcg PO;
6-12 years: 12.5/50-18.75/75 mcg PO;
>12 years: >18.75/75 mcg PO;
Administration: Before breakfast
Interactions
Interaction Checker
No Results
Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor
Contraindicated (1)
- sodium iodide I-131
liotrix will decrease the level or effect of sodium iodide I-131 by Other (see comment). Contraindicated. Use of thyroid products or iodine before and during treatment with sodium iodide I-131 decreases uptake of sodium iodide I-131 by the thyroid gland
Serious - Use Alternative (0)
Monitor Closely (8)
- didanosine
didanosine will decrease the level or effect of liotrix by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Applies to didanosine chewable tablets and powder for oral solution; administer 2 hr before or several hours after didanosine oral solution or chewable tablet administration
- insulin degludec
liotrix decreases effects of insulin degludec by pharmacodynamic antagonism. Use Caution/Monitor. Thyroid hormones regulate carbohydrate metabolism, gluconeogenesis, and glycogen stores mobilization; dose of antidiabetic agents may need adjustment and increased frequency of glucose monitoring may be required.
- insulin degludec/insulin aspart
liotrix decreases effects of insulin degludec/insulin aspart by pharmacodynamic antagonism. Use Caution/Monitor. Thyroid hormones regulate carbohydrate metabolism, gluconeogenesis, and glycogen stores mobilization; dose of antidiabetic agents may need adjustment and increased frequency of glucose monitoring may be required.
- insulin inhaled
liotrix decreases effects of insulin inhaled by pharmacodynamic antagonism. Use Caution/Monitor. Thyroid hormones regulate carbohydrate metabolism, gluconeogenesis, and glycogen stores mobilization; dose of antidiabetic agents may need adjustment and increased frequency of glucose monitoring may be required.
- lanthanum carbonate
lanthanum carbonate decreases levels of liotrix by cation binding in GI tract. Use Caution/Monitor. Administer oral thyroid products at least 2 hr before or after lanthanum. Interaction applies only to oral thyroid products only. .
- levonorgestrel oral/ethinylestradiol/ferrous bisglycinate
levonorgestrel oral/ethinylestradiol/ferrous bisglycinate will decrease the level or effect of liotrix by unknown mechanism. Modify Therapy/Monitor Closely. The estrogen component of combined hormonal contraceptives (CHCs) may raise the serum concentrations of thyroxine-binding globulin. Women on thyroid hormone replacement therapy may need increased doses of thyroid hormone with use of CHCs.
- metformin
liotrix decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor. Patient should be closely observed for loss of blood glucose control; when drugs are withdrawn from a patient receiving metformin, patient should be observed closely for hypoglycemia.
- nateglinide
liotrix decreases effects of nateglinide by pharmacodynamic antagonism. Use Caution/Monitor. Coadministration may reduce nateglinide's hypoglycemic action.
Minor (7)
- dexlansoprazole
dexlansoprazole decreases levels of liotrix by increasing gastric pH. Applies only to oral form of both agents. Minor/Significance Unknown. Conflicting evidence regarding this interaction exists.
- esomeprazole
esomeprazole decreases levels of liotrix by increasing gastric pH. Applies only to oral form of both agents. Minor/Significance Unknown. Conflicting evidence regarding this interaction exists.
- furosemide
furosemide increases toxicity of liotrix by Other (see comment). Minor/Significance Unknown. Comment: High doses (greater than 80 mg) of furosemide may inhibit binding of thyroid hormones to carrier proteins and result in transient increase in free thyroid hormones, followed by overall decrease in total thyroid hormone levels.
- lansoprazole
lansoprazole decreases levels of liotrix by increasing gastric pH. Applies only to oral form of both agents. Minor/Significance Unknown. Conflicting evidence regarding this interaction exists.
- omeprazole
omeprazole decreases levels of liotrix by increasing gastric pH. Applies only to oral form of both agents. Minor/Significance Unknown. Conflicting evidence regarding this interaction exists.
- pantoprazole
pantoprazole decreases levels of liotrix by increasing gastric pH. Applies only to oral form of both agents. Minor/Significance Unknown. Conflicting evidence regarding this interaction exists.
- rabeprazole
rabeprazole decreases levels of liotrix by increasing gastric pH. Applies only to oral form of both agents. Minor/Significance Unknown. Conflicting evidence regarding this interaction exists.
Adverse Effects
Frequency Not Defined
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
Black Box Warnings
Thyroid hormones, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight loss
In euthyroid patients, doses within the range of daily hormonal requirements are ineffective for weight reduction. Larger doses may produce serious or even life-threatening manifestations of toxicity, particularly when given in association with sympathomimetic amines such as those used for their anorectic effects.
Contraindications
Hypersensitivity to thyroid hormone
Acute MI uncomplicated by hypothyroidism, untreated thyrotoxicosis, untreated adrenal insufficiency
Treatment of obesity
Cautions
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 & Lactation
Pregnancy Category: A
Lactation: Small amount excreted into breast milk, use caution
Pregnancy Categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available.Pharmacology
Mechanism of Action
Natural thyroid hormone; increases basal metabolic rate, increases utilization and mobilization of glycogen store, promotes gluconeogenesis
Pharmacokinetics
Half-Life (T4): 6-7 days (euthyroid); 3-4 days (hyperthyroid); 9-10 days (hypothyroid)
Half-life (T3): 2.5 days
Onset: 48 hr
Absorption: 40-80% (T4); 95% (T3)
Max effect: 8-10 days
Peak Plasma Time: 12-48 hr
Bioavailability: 50-95%
Protein Bound: 99% (T4)
Metabolism: Liver, also in kidney & intestinal walls
Metabolites: Triiodothyronine (T3)
Excretion: Urine (major), feces
Images
| BRAND | FORM. | UNIT PRICE | PILL IMAGE |
|---|---|---|---|
| Thyrolar-1 oral - | 12.5-50 mcg tablet |  | |
| Thyrolar-2 oral - | 25-100 mcg tablet |  | |
| Thyrolar-1/4 oral - | 3.1-12.5 mcg tablet |  | |
| Thyrolar-3 oral - | 37.5-150 mcg tablet |  | |
| Thyrolar-1/2 oral - | 6.25-25 mcg tablet |  |
Copyright © 2010 First DataBank, Inc.
Patient Handout
liotrix oral
LIOTRIX - ORAL
(LYE-oh-tricks)
COMMON BRAND NAME(S): Thyrolar
WARNING: This medication should not be used for weight loss. Normal doses of this medication will not work for weight loss, and large doses of this medication may cause serious, possibly fatal side effects, especially when taken with diet pills.
USES: See also Warning section.Liotrix is used to treat an underactive thyroid (hypothyroidism). It replaces or provides more of a certain natural substance (thyroid hormone) that is normally produced by the thyroid gland. Low thyroid hormone levels can occur naturally or when the thyroid gland is injured by radiation/medications or removed by surgery. Having enough thyroid hormone in your bloodstream is important for maintaining normal mental and physical activity. In children, having enough thyroid hormone is important for normal mental and physical development.This medication is also used to treat other types of thyroid disorders (e.g., certain types of goiters, thyroid cancer). It can also be used to test for certain types of thyroid disease.This medication should not be used to treat infertility unless it is caused by low thyroid hormone levels.
HOW TO USE: Take this medication by mouth, usually once a day on an empty stomach, 30 minutes to 1 hour before breakfast, or as directed by your doctor.Dosage is based on your medical condition, laboratory test results, and response to treatment. For children, the dosage is also based on age. Your doctor will usually start you on a low dose and slowly increase your dose as needed.Use this medication regularly in order to get the most benefit from it. To help you remember, take it at the same time each day.Do not stop taking this medication without first consulting with your doctor. Thyroid replacement treatment is usually taken for life.Symptoms of low thyroid hormone levels include tiredness, muscle aches, constipation, dry skin, weight gain, slow heartbeat, or sensitivity to cold. Tell your doctor if your condition worsens or persists after several weeks of taking this medication.
SIDE EFFECTS: Some hair loss may occur during the first few months of starting this drug. This effect is usually temporary as your body adjusts to this medication. If this effect persists or worsens, tell your doctor or pharmacist promptly.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor right away if any of these unlikely but serious effects of high thyroid hormone levels occur: diarrhea, bone pain, headache, mental/mood changes (e.g., nervousness, mood swings), shaking (tremor), sensitivity to heat, increased sweating, tiredness.Seek immediate medical attention if any of these rare but very serious effects of high thyroid hormone levels occur: chest pain, fast/pounding/irregular heartbeat, seizures, swelling of the ankles/feet.A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
PRECAUTIONS: Before taking liotrix, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: increased thyroid hormones (thyrotoxicosis), a heart attack (acute myocardial infarction), adrenal gland problem (e.g., uncorrected adrenal insufficiency).Before using this medication, tell your doctor or pharmacist your medical history, especially of: heart disease (e.g., coronary artery disease, irregular heartbeat), high blood pressure, diabetes, other hormone disorders (e.g., decreased pituitary hormone).If you have diabetes, this medication may increase your blood sugar. Check your blood sugar regularly as directed and share the results with your doctor. Tell your doctor right away if you have symptoms of high blood sugar, such as increased thirst/urination. Your doctor may need to adjust your diabetes medication, exercise program, or diet.Before having surgery, tell your doctor or dentist that you are taking this medication.Caution is advised when using this drug in the elderly because they may be more sensitive to the effects on the heart caused by high thyroid hormone level.Current information shows that this drug may be used during pregnancy. Tell your doctor if you are pregnant or if you become pregnant because your dose may need to be adjusted.Small amounts of this medication pass into breast milk. Consult your doctor before breast-feeding.
DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.Some products that may interact with this drug include: androgens/anabolic steroids, beta blockers (e.g., propranolol), "blood thinners" (e.g., warfarin), corticosteroids (e.g., dexamethasone), cytokines (e.g., interferon-alpha, interleukin-2), digoxin, drugs affecting liver enzymes that remove liotrix from your body (such as phenobarbital, rifamycins including rifabutin, certain anti-seizure medicines including phenytoin), drugs that can decrease thyroid hormone levels (e.g., amiodarone, medications containing iodide/iodine, lithium), estrogen-containing products (including birth control pills), growth hormones, medications for depression (including maprotiline, tricyclic antidepressants such as amitriptyline, SSRIs such as sertraline).Certain medications (cholestyramine, colestipol, antacids, sucralfate, simethicone, iron, sodium polystyrene sulfonate, calcium carbonate, orlistat) can decrease the amount of liotrix that is absorbed by your body . If you are taking any of these drugs, separate them from this medication by at least 4 hours.Check the labels on all your medicines (e.g., cough-and-cold products, diet aids) because they may contain ingredients such as decongestants or caffeine that could increase your heart rate or blood pressure. Ask your pharmacist about using those products safely.
OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: fast/pounding/irregular heartbeat, loss of consciousness, confusion, trouble speaking, seizures.
NOTES: Do not share this medication with others.Laboratory and/or medical tests (e.g., thyroid stimulating hormone-TSH levels) should be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.
MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up unless your doctor instructs you to do so. Call your doctor if you miss 2 or more doses in a row. Ask your doctor ahead of time what to do about a missed dose and follow your doctor's specific directions.
STORAGE: Store in the refrigerator away from light. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.
Information last revised August 2021. Copyright(c) 2021 First Databank, Inc.
IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.
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