Generic Name

Liothyronine Sodium

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Classification

FDA Approved Indications

• Treatment of myxedema coma or severe hypothyroidism

Mechanism of Action

Liothyronine sodium is a synthetic form of the active thyroid hormone T3, which increases metabolic rate, protein synthesis, and overall growth and development processes by binding to nuclear thyroid hormone receptors and modulating gene transcription.

Dosage and Administration

Adult: Typically 25 mcg daily, titrated based on response and laboratory tests.

Pediatric: Dosage varies based on age and weight; consult pediatric endocrinology guidelines.

Geriatric: Start at lower doses due to increased sensitivity and risk of cardiovascular side effects.

Renal Impairment: Use with caution; adjust dose based on clinical response.

Hepatic Impairment: Use cautiously; monitor closely, as metabolism may be altered.

Pharmacokinetics

Absorption: Rapidly absorbed from gastrointestinal tract

Distribution: Widely distributed in body tissues, crosses placenta, present in breast milk

Metabolism: Metabolized primarily in the liver and kidneys

Excretion: Excreted mainly in urine

Half Life: Approximately 2.5 days in healthy adults, shorter in hyperthyroid states

Contraindications

• Untreated thyrotoxicosis
• Recent myocardial infarction

Precautions

• Cardiovascular disease, elderly patients, and those with adrenal insufficiency should be monitored closely.
• Use with caution in patients with diabetes mellitus, as dose adjustments may be necessary.

Adverse Reactions - Common

• Heat intolerance (Common)
• Tachycardia (Common)
• Sweating (Common)

Adverse Reactions - Serious

• Arrhythmias (Rare)
• Osteoporosis with long-term use (Rare)

Drug-Drug Interactions

• Warfarin (increased anticoagulant effect), catecholamines (enhanced cardiotoxicity), digoxin (altered levels)

Drug-Food Interactions

• High iodine foods may influence thyroid function, but not directly interact with T3

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Take medication exactly as prescribed, usually in the morning on an empty stomach.
• Report symptoms of hyperthyroidism (e.g., rapid heartbeat, weight loss, nervousness) or hypothyroidism (e.g., fatigue, cold intolerance).
• Regular follow-up appointments and lab tests are important for dose adjustments.

Special Considerations

Black Box Warnings:

• None specific for this medication.

Genetic Factors: Thyroid drug response may vary based on genetic differences affecting metabolism.

Lab Test Interference: Can alter thyroid function test results, leading to misinterpretation if not aware.

Overdose Management

Signs/Symptoms: Symptoms of overdose include hyperthyroidism, including tachycardia, agitation, tremors, weight loss, and heat intolerance.

Treatment: Discontinue medication, provide supportive care such as beta-blockers for symptomatic relief, and hospitalize if severe symptoms occur.

Storage and Handling

Storage: Store at room temperature, away from light and moisture.

Stability: Stable when stored properly, check manufacturer’s expiration date.