Levothyroxine Capsule

Levothyroxine Capsules
Usage
Levothyroxine capsules are an oral formulation of a synthetic thyroid hormone (T4) used to replace or supplement endogenous thyroid hormone in patients with thyroid hormone deficiency.
They may be prescribed for:
• Hypothyroidism (primary, secondary, or tertiary)
• Thyroid hormone replacement therapy after thyroidectomy
• Suppression of thyroid-stimulating hormone (TSH) in certain thyroid conditions (e.g., thyroid cancer)
• Other practitioner-directed endocrine indications
Compounded capsules may be used when precise or customised dosing is required.

Dosage
Dosage should be individualised and determined by the prescribing practitioner based on clinical response and laboratory values (e.g., TSH, free T4).
Typical dosing considerations include:
• Usually administered once daily
• Taken on an empty stomach, preferably 30–60 minutes before breakfast
• Capsules should be taken with water only
• Dose adjustments are made gradually based on thyroid function tests
Consistency in timing and administration is important for optimal effect.

Mechanisms of Action
Levothyroxine is a synthetic form of thyroxine (T4).
Its mechanisms include:
Conversion to active hormone (T3)
Levothyroxine is converted in peripheral tissues to triiodothyronine (T3), the active form of thyroid hormone.
Regulation of metabolism
Thyroid hormones regulate metabolic rate, energy production, and oxygen consumption.
Effects on multiple organ systems
They influence cardiovascular function, growth, development, and neurological function.
Replacement therapy restores normal physiological thyroid hormone levels.

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

Precautions
Levothyroxine should be used with caution in patients with:
• Cardiovascular disease (e.g., coronary artery disease, arrhythmias)
• Elderly patients, who may require lower starting doses
• Adrenal insufficiency
• Diabetes mellitus, as thyroid hormone may affect glucose control
Additional considerations include:
• Regular monitoring of TSH and thyroid hormone levels is essential
• Over-replacement may cause symptoms of hyperthyroidism, such as:
• Palpitations
• Weight loss
• Anxiety
• Insomnia
• Under-treatment may result in persistent hypothyroid symptoms
• Absorption may be affected by certain foods and medications (e.g., calcium, iron supplements)
Patients should seek medical advice if they experience chest pain, rapid heartbeat, or significant changes in symptoms.

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