liotrix (Rx)

Brand and Other Names:Thyrolar
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Dosing & Uses

AdultPediatric

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

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Interactions

Interaction Checker

and liotrix

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    No Interactions Found
    Interactions Found

    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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            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.

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              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

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              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

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              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.

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              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

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              Patient Handout

              A Patient Handout is not currently available for this monograph.
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              Formulary

              FormularyPatient Discounts

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              Tier Description
              1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
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              NC NOT COVERED – Drugs that are not covered by the plan.
              Code Definition
              PA Prior Authorization
              Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
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              Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.