Levothyroxine Sodium Tablets (Euthyrox) is a medication used for the treatment of hypothyroidism and thyroid cancer. As a key drug in thyroid hormone replacement therapy, the correct use of Euthyrox is crucial for ensuring therapeutic efficacy.

How to Use Levothyroxine Sodium Tablets (Euthyrox)

Administration Timing

Levothyroxine Sodium Tablets should be taken once daily on an empty stomach, preferably 30-60 minutes before breakfast.

This administration method helps the drug be absorbed more effectively, ensuring optimal therapeutic results.

If a patient cannot take the drug before breakfast, taking it at bedtime is an alternative—however, it is essential to ensure the stomach has been empty for at least 4 hours before administration.

Administration Method

Levothyroxine Sodium Tablets should be swallowed whole with warm water.

For children who cannot swallow whole tablets, the tablets can be crushed and suspended in a small amount of water (5-10 mL or 1-2 teaspoons), then administered immediately using a spoon or dropper.

Crushed tablets cannot be stored and must be taken right away. They should not be administered together with foods that may reduce drug absorption (e.g., soy-based infant formula).

Precautions for Drug Interactions

Levothyroxine Sodium Tablets interact with a variety of medications—especially calcium-containing, iron-containing drugs, and antacids, which can impair its absorption.

These interacting medications should be taken at least 4 hours apart from Levothyroxine Sodium Tablets.

Soy flour, cottonseed meal, walnuts, and dietary fiber may bind to Levothyroxine Sodium Tablets and reduce their absorption.

Grapefruit juice may delay the absorption of levothyroxine and decrease its bioavailability.

Dose Adjustment of Levothyroxine Sodium Tablets (Euthyrox)

General Dosage Principles

The dose of Levothyroxine Sodium Tablets should be individually adjusted based on the patient’s age, body weight, cardiovascular status, concurrent diseases, concurrent medications, co-ingested foods, and the specific condition being treated.

The peak therapeutic effect may take 4-6 weeks to achieve, so dose adjustments should not be made too frequently.

Basis for Dose Adjustment

Dose adjustments of Levothyroxine Sodium Tablets should be based on regular laboratory tests and clinical evaluations.

For adult patients with primary hypothyroidism, serum thyroid-stimulating hormone (TSH) levels should be monitored 6-8 weeks after any dose change.

For patients with stable conditions and appropriate doses, clinical and biochemical responses should be evaluated every 6-12 months, or when the patient’s clinical status changes.

Management of Poor Therapeutic Response

For patients with poor therapeutic response, the first step is to assess medication adherence, administered dose, and administration method.

In adult patients, it is rare to see no adequate response even with a daily dose exceeding 300 mcg. If this occurs, the possibility of malabsorption should be considered.

Medication for Special Populations with Primary Hypothyroidism

Geriatric Patients

Due to the increased prevalence of cardiovascular diseases in the elderly, Levothyroxine Sodium Tablets should be initiated at a dose lower than the full replacement dose.

Geriatric patients may require a full replacement dose of less than 1 mcg/kg/day.

Atrial fibrillation is the most common arrhythmia in elderly patients receiving excessive thyroid hormone therapy.

Pediatric Patients

The recommended daily dose of Levothyroxine Sodium Tablets for children is based on body weight and varies with age.

Most pediatric patients should start with the full daily dose.

For neonates (0-3 months) at risk of heart failure and children at risk of hyperactivity, treatment should be initiated at a lower starting dose.