Levotiroxina Sódica Teva (Levothyroxine Sodium)

Levotiroxina Sódica Teva is a synthetic thyroid hormone used in disorders of thyroid hormone deficiency.

• Hypothyroidism: restores normal metabolic activity by supplying the missing thyroxine (T4).
• Post‑thyroidectomy hormone replacement: provides the thyroid hormone that the body can no longer produce after surgical removal of the gland.
• Goiter: helps normalize thyroid hormone levels, reducing compensatory gland enlargement.

• Levothyroxine sodium is a synthetic analogue of the endogenous hormone thyroxine (T4). After oral absorption, it is converted to the active triiodothyronine (T3) within peripheral tissues. The hormone binds nuclear thyroid receptors, modulating gene transcription that regulates basal metabolic rate, protein synthesis, and growth. By restoring normal hormone concentrations, it normalizes the physiological processes that depend on thyroid activity.

Levotiroxina Sódica Teva may cause a range of adverse reactions, most of which are dose‑related and reversible upon adjustment.

Common Side Effects

• Headache: mild to moderate intensity.
• Insomnia: difficulty falling or staying asleep.
• Palpitations: sensation of rapid or irregular heartbeat.
• Weight loss: unintended reduction in body weight.
• Heat intolerance: increased sensitivity to warm environments.
• Tremor: fine shaking of the hands.

Serious or Rare Side Effects

• Cardiac arrhythmia: abnormal heart rhythm that may require medical attention.
• Angina pectoris: chest pain due to reduced coronary blood flow.
• Myocardial infarction: rare but possible heart attack in susceptible patients.
• Severe allergic reaction: rash, swelling, or anaphylaxis.
• Bone loss (osteoporosis): long‑term overtreatment may affect bone density.
• Adrenal insufficiency: may precipitate adrenal crisis in patients with untreated adrenal disease.

Levotiroxina Sódica Teva requires careful monitoring to avoid over‑ or under‑replacement.

• Dose titration: adjust gradually, especially in elderly or cardiac patients.
• Thyroid function monitoring: check serum TSH and free T4 levels regularly.
• Cardiovascular risk: use caution in patients with coronary artery disease or arrhythmias.
• Pregnancy and lactation: discuss risks with a healthcare professional; data are limited.
• Drug discontinuation: do not stop abruptly without medical guidance.
• Store at ambient temperature: keep below 25°C, retain in original container, protect from moisture and direct sunlight.

Levotiroxina Sódica Teva can interact with several medicines that affect its absorption or metabolism.

Major Interactions (Avoid)

• Calcium supplements: reduce levothyroxine absorption.
• Iron salts: markedly decrease oral bioavailability.
• Sucralfate: binds the drug and impairs uptake.
• Cholestyramine and other bile‑acid sequestrants: lower systemic exposure.
• Antacids containing aluminum or magnesium: interfere with absorption.

Moderate Interactions (Monitor Closely)

• Warfarin: may enhance anticoagulant effect, requiring INR monitoring.
• Oral contraceptives: can increase levothyroxine requirements.
• Amiodarone: alters thyroid hormone metabolism.
• Rifampin: accelerates clearance, possibly necessitating dose increase.
• Carbamazepine: induces hepatic enzymes, reducing drug levels.