Liothyronine Capsule

Liothyronine Capsules
Usage
Liothyronine capsules contain synthetic triiodothyronine (T3), the active thyroid hormone, and are used for the management of thyroid hormone deficiency and selected endocrine conditions. Compared with levothyroxine (T4), liothyronine has a more rapid onset and shorter duration of action.
They may be prescribed for:
• Hypothyroidism (in selected patients or when T4 alone is inadequate)
• Myxoedema coma (specialist setting)
• TSH suppression therapy (e.g., certain thyroid cancers)
• Situations requiring rapid thyroid hormone effect
• Other practitioner-directed endocrine uses
Compounded capsules may be used when precise or individualised dosing is required.

Dosage
Dosage should be individualised and prescribed by a qualified healthcare professional, based on clinical response and thyroid function tests.
Typical dosing considerations include:
• Usually administered once or multiple times daily due to shorter half-life
• Often started at a low dose and titrated gradually
• May be taken with or without food, but consistency is important
• Dose adjustments are guided by TSH, free T3, and free T4 levels
Careful monitoring is essential to avoid over- or under-replacement.

Mechanisms of Action
Liothyronine is a synthetic form of triiodothyronine (T3), the biologically active thyroid hormone.
Its mechanisms include:
Direct hormonal activity
Liothyronine acts directly on thyroid hormone receptors without requiring conversion.
Regulation of gene expression
It influences transcription of genes involved in metabolism, growth, and development.
Increase in metabolic rate
Enhances basal metabolic rate, oxygen consumption, and energy production.
Effects on multiple organ systems
Affects cardiovascular, neurological, and musculoskeletal systems, supporting normal physiological function.

Contraindications
Liothyronine should not be used in patients with:
• Untreated thyrotoxicosis (hyperthyroidism)
• Uncorrected adrenal insufficiency
• Hypersensitivity to liothyronine or formulation components

Precautions
Liothyronine should be used with caution in patients with:
• Cardiovascular disease (e.g., angina, arrhythmias, hypertension)
• Elderly patients, who may require lower initial doses
• Adrenal insufficiency
• Diabetes mellitus, as thyroid hormones may affect glycaemic control
Additional considerations include:
• Risk of over-replacement, which may cause symptoms such as:
• Palpitations
• Tachycardia
• Anxiety
• Insomnia
• Regular monitoring of thyroid function tests is essential
• Abrupt dose changes should be avoided
• May interact with medications affecting thyroid hormone absorption or metabolism
Patients should seek medical advice if they experience chest pain, rapid heartbeat, or worsening symptoms.

Storage
• Store below 25°C unless otherwise directed
• Keep capsules in a tightly closed container
• Protect from heat, moisture, and light, as liothyronine may be sensitive to degradation
• Keep out of reach of children and pets
Patients should follow the storage instructions provided on the dispensing label supplied by the pharmacy.