Levothyroxine Teva Uk (Levothyroxine Sodium)

Levothyroxine is indicated for conditions related to thyroid hormone deficiency and thyroid tissue growth.

• Hypothyroidism: restores normal thyroid hormone levels, alleviating fatigue, weight gain, and cold intolerance.
• Goiter: reduces thyroid gland enlargement by normalizing hormone feedback mechanisms.
• Thyroid cancer suppression: provides hormone replacement after thyroidectomy to suppress TSH stimulation of residual cancer cells.

• Levothyroxine is a synthetic form of the endogenous hormone thyroxine (T4). After oral absorption, it is converted to the active hormone triiodothyronine (T3) within cells. The hormone binds nuclear thyroid hormone receptors, modulating gene transcription that controls basal metabolic rate, protein synthesis, and sympathetic nervous system activity, thereby compensating for deficient thyroid function.

Levothyroxine may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Headache: mild to moderate pain in the head.
• Insomnia: difficulty falling or staying asleep.
• Palpitations: sensation of rapid or irregular heartbeat.
• Weight loss: unintended decrease 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 be life‑threatening.
• Angina pectoris: chest pain due to reduced coronary blood flow.
• Myocardial infarction: heart attack resulting from blocked coronary arteries.
• Severe hyperthyroidism: excessive thyroid activity causing agitation and fever.
• Bone loss (osteoporosis): decreased bone mineral density with long‑term use.
• Anaphylaxis: rare severe allergic reaction requiring immediate medical attention.

When prescribing Levothyroxine, clinicians should observe several safety considerations to minimize risk.

• Monitor thyroid function: check TSH and free T4 levels regularly to adjust dose.
• Dose adjustment in elderly: start with lower doses and titrate slowly.
• Cardiovascular caution: evaluate patients with angina, arrhythmias, or recent myocardial infarction before initiating therapy.
• Avoid abrupt discontinuation: taper the dose to prevent rebound hypothyroidism.
• Pregnancy and lactation: use only if benefits outweigh potential risks, under medical supervision.
• Store at room temperature: keep tablets in the original container, protect from moisture and direct sunlight.

Levothyroxine's absorption and activity can be altered by several concomitant medicines.

Major Interactions (Avoid)

• Calcium supplements: bind levothyroxine in the gut, markedly reducing absorption.
• Iron salts: decrease levothyroxine uptake when taken simultaneously.
• Antacids containing aluminum or magnesium: impair absorption if co‑administered.
• Cholestyramine and other bile‑acid sequestrants: lower levothyroxine bioavailability.
• Sucralfate: forms complexes that diminish levothyroxine absorption.

Moderate Interactions (Monitor Closely)

• Warfarin: levothyroxine may enhance anticoagulant effect, requiring INR monitoring.
• Oral contraceptives: may increase levothyroxine binding, necessitating dose review.
• Amiodarone: can affect thyroid hormone metabolism, requiring careful thyroid function monitoring.
• Beta‑blockers: may mask symptoms of excess thyroid hormone.
• SSRIs: may potentiate mood changes when thyroid levels fluctuate.