Liothyronine

Liothyronine

Drug monograph · NCLEX study reference
Trade names	Cytomel
Therapeutic class	Thyroid hormone replacement
Pharmacologic class	Synthetic T3
Onset / peak / duration	Onset within hours; shorter duration than levothyroxine.
Half-life / level	Half-life about 1 to 2 days; goal normal thyroid status.
Routes	PO (oral), IV
High-alert (ISMP)	No
Black box warning	Yes (see Safety)
Antidote / reversal	Dose reduction.
Pregnancy / lactation	Levothyroxine usually preferred.

Nursing pharmacology study reference (NCLEX-style monograph). Numeric values are standard teaching ranges for study and must be verified against current manufacturer labeling before clinical use. This is educational content, not prescribing guidance.

Liothyronine (brand name Cytomel) — Thyroid hormone replacement; Synthetic T3.

Identification

• Therapeutic class: Thyroid hormone replacement.
• Pharmacologic class: Synthetic T3.

Pharmacology

• Mechanism of action: Replaces triiodothyronine; faster onset and shorter action than T4.
• Onset / peak / duration: Onset within hours; shorter duration than levothyroxine.
• Half-life / therapeutic level: Half-life about 1 to 2 days; goal normal thyroid status.

Clinical use

• Indications: Hypothyroidism, myxedema coma (IV), thyroid suppression testing.
• Usual dose, route, frequency: 5 to 25 mcg PO daily; IV in myxedema coma.
• Maximum dose / adjustments: Start low in elderly and cardiac disease.

Safety

• Contraindications: Acute MI, untreated adrenal insufficiency, thyrotoxicosis.
• Black box warning: Not for weight loss.
• Interactions: Same as levothyroxine.
• Pregnancy / lactation: Levothyroxine usually preferred.
• High-alert: No.

Adverse effects

• Common side effects: Usually none at correct dose.
• Serious effects to report: Overtreatment symptoms, chest pain, arrhythmia.
• Antidote / reversal: Dose reduction.

Nursing process

• Assessment before administration: Thyroid labs, heart rate, cardiac history.
• Interventions during therapy: Monitor closely because of rapid action.
• Monitor: Thyroid labs, heart rate, symptoms.
• Evaluation / expected outcome: Normalized thyroid status.

Patient teaching

• Patient teaching: Consistent timing; report palpitations.
• Notify provider if: Chest pain, palpitations, tremor.
• Administration tips: Consistent daily timing.