Levotiroxina Teva (Levothyroxine Sodium)

Levotiroxina Teva is a thyroid hormone replacement that acts on the hypothalamic‑pituitary‑thyroid axis to normalize metabolic function.

• Hypothyroidism: restores normal thyroid hormone levels and alleviates symptoms such as fatigue, weight gain, and cold intolerance.
• Post‑thyroidectomy: provides necessary hormone replacement after surgical removal of the thyroid gland.
• Goiter: reduces gland enlargement by supplying adequate hormone and suppressing TSH stimulation.

• Levothyroxine sodium is a synthetic form of the endogenous hormone thyroxine (T4). After oral absorption, it is converted to the active hormone triiodothyronine (T3) in peripheral tissues. The hormone binds nuclear thyroid receptors, modulating gene transcription that regulates basal metabolic rate, protein synthesis, and growth. By restoring circulating thyroid hormone concentrations, it normalizes the feedback loop with the pituitary gland, reducing elevated thyroid‑stimulating hormone (TSH) levels.

Levotiroxina Teva may cause adverse reactions that vary in frequency and severity.

Common Side Effects

• Headache: mild to moderate pain often occurring early in therapy.
• 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 or limbs.

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: heart attack in susceptible individuals.
• Osteoporosis: decreased bone mineral density with long‑term overtreatment.
• Severe allergic reaction: rash, swelling, or difficulty breathing.
• Adrenal crisis: life‑threatening insufficiency in patients with adrenal disease.

Levotiroxina Teva requires careful monitoring and patient education to minimize risks.

• Thyroid function monitoring: regularly assess TSH and free T4 levels to adjust dose.
• Cardiovascular disease: start with low dose and titrate slowly in patients with heart disease.
• Elderly patients: consider reduced initial dose due to altered metabolism.
• Pregnancy and lactation: use only if clearly needed; discuss risks with a healthcare provider.
• Discontinuation: do not stop abruptly without medical guidance.
• Store at room temperature: keep in the original container, protect from moisture and direct sunlight.

Levotiroxina Teva can interact with several medicines and supplements, affecting its absorption or action.

Major Interactions (Avoid)

• Calcium supplements: bind levothyroxine and reduce its absorption.
• Iron salts: significantly decrease oral bioavailability.
• Antacids containing aluminum or magnesium: impair absorption when taken concurrently.
• Cholestyramine: sequesters the drug and lowers systemic exposure.
• Sucralfate: forms complexes that limit levothyroxine uptake.

Moderate Interactions (Monitor Closely)

• Warfarin: levothyroxine may enhance anticoagulant effect; monitor INR.
• Oral contraceptives: may increase thyroid‑binding globulin, altering hormone levels.
• Amiodarone: can affect thyroid function and require dose adjustments.
• Carbamazepine: induces hepatic enzymes, potentially lowering levothyroxine levels.
• Phenytoin: increases metabolism of thyroid hormone, necessitating monitoring.