Product image of Levothyroxine (Levothyroxine Sodium) supplied by GNH India

Levothyroxine

Active Ingredient:
Levothyroxine Sodium
Origin:
EU

Levothyroxine (Levothyroxine Sodium)

Levothyroxine Sodium, the active ingredient in Levothyroxine, is a synthetic thyroid hormone presented as an oral tablet for oral use. It is used to treat hypothyroidism and related thyroid disorders in adults and children requiring hormone replacement throughout their lives under medical supervision.

GNH India supplies Levothyroxine as a licensed, GDP‑compliant international pharmaceutical supplier serving hospitals, pharmacies and clinics worldwide. The company adheres to stringent quality standards and provides reliable sourcing for regulated markets across Europe, Asia and the Americas through established distribution networks.

Manufacturer / TM Owner

Wockhardt Uk Ltd

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Indications & Clinical Uses

Levothyroxine is used to replace deficient thyroid hormone in conditions affecting the thyroid gland.

  • Hypothyroidism: restores normal metabolic rate and alleviates symptoms such as fatigue and weight gain.
  • Goiter: reduces thyroid‑stimulating hormone levels to help shrink enlarged thyroid tissue.
  • Post‑thyroidectomy: provides necessary hormone replacement after surgical removal of the thyroid.
  • Congenital hypothyroidism: ensures adequate thyroid hormone for growth and neurodevelopment in infants.

How It Works

  • Levothyroxine sodium supplies exogenous thyroxine (T4), which is absorbed from the gastrointestinal tract and converted peripherally to the active hormone triiodothyronine (T3). Both T4 and T3 bind nuclear thyroid hormone receptors, modulating gene transcription that regulates basal metabolic rate, protein synthesis, and growth. By restoring normal hormone levels, the drug normalizes the hypothalamic‑pituitary‑thyroid feedback loop.

Side Effects

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

Common Side Effects

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

Serious or Rare Side Effects

  • Arrhythmia: abnormal heart rhythm that may require medical attention.
  • Angina pectoris or myocardial infarction: chest pain or heart attack due to excess thyroid activity.
  • Severe hyperthyroidism: symptoms such as severe tachycardia, agitation, and fever.
  • Bone loss (osteoporosis): decreased bone mineral density with long‑term overtreatment.
  • Allergic reaction: rash, itching, swelling, or anaphylaxis in rare cases.

Precautions & Warnings

When prescribing Levothyroxine, clinicians should consider several safety measures.

  • Thyroid function monitoring: regular TSH and free T4 tests are required to adjust dose.
  • Dose adjustment in elderly: start with lower dose and titrate cautiously.
  • Cardiovascular disease: assess for angina or arrhythmia before increasing dose.
  • Adrenal insufficiency: ensure adequate glucocorticoid replacement before initiating therapy.
  • Pregnancy and lactation: use only if benefits outweigh risks, as safety data are limited.
  • Store at room temperature: keep in original container, protect from moisture and light.

Avoid Interactions

Levothyroxine interacts with several medicines that may alter its absorption or effect.

Major Interactions (Avoid)

  • Antacids containing aluminum or magnesium: reduce levothyroxine absorption.
  • Calcium supplements: interfere with absorption when taken concurrently.
  • Iron salts: markedly decrease levothyroxine bioavailability.
  • Warfarin: levothyroxine may enhance anticoagulant effect, requiring INR monitoring.
  • Amiodarone: alters thyroid hormone metabolism and may precipitate dysfunction.

Moderate Interactions (Monitor Closely)

  • Statins: may increase risk of myopathy when thyroid hormone levels are high.
  • Beta‑blockers: may mask symptoms of excess thyroid hormone.
  • Oral contraceptives: can increase thyroxine binding, possibly requiring dose adjustment.
  • SSRIs: may affect thyroid hormone levels, necessitating monitoring.
  • Diabetes medications: altered glucose metabolism may occur with thyroid hormone changes.

Frequently Asked Questions

Levothyroxine is prescribed to replace deficient thyroid hormone in patients with hypothyroidism, goiter, post‑thyroidectomy states, and congenital hypothyroidism. By restoring normal hormone levels, it helps regulate metabolism, energy production, and growth.

The drug provides synthetic thyroxine (T4) that is absorbed and converted to the active hormone triiodothyronine (T3). T3 and T4 bind to nuclear thyroid receptors, influencing gene expression that controls basal metabolic rate, protein synthesis, and developmental processes.

Dosage is individualized and set by the prescribing clinician based on factors such as age, weight, severity of thyroid deficiency, cardiac status, and laboratory results (TSH and free T4). Regular monitoring guides any dose adjustments.

Safety data are limited, so Levothyroxine should be used in pregnancy or lactation only when the expected benefit outweighs potential risks. Thyroid hormone is essential for fetal development, and untreated hypothyroidism can be harmful, so clinicians often continue therapy with careful monitoring.

Submit an enquiry on the product page at gnhindia.com, specifying the required quantity. GNH India works with hospitals, pharmacies and procurement teams worldwide, verifies trade or institutional credentials, and then provides pricing, availability, shipping details and any necessary import documentation.

Levothyroxine is the standard synthetic T4 replacement and is preferred for most patients because of its predictable pharmacokinetics and long half‑life. Alternatives such as liothyronine (synthetic T3) or desiccated thyroid extract provide T3 directly but may cause more fluctuations in hormone levels.

Store the tablets at room temperature, below 25 °C, in the original container to protect them from moisture and light. Do not expose the product to excessive heat or humidity, and keep it out of reach of children.

Levothyroxine is taken orally, usually on an empty stomach 30‑60 minutes before breakfast. The tablet should be swallowed whole with a full glass of water; it should not be crushed, chewed, or taken with other medications that could interfere with absorption.

Serious risks include cardiac arrhythmias, angina or myocardial infarction due to overtreatment, severe hyperthyroidism, and bone loss with long‑term excess dosing. Patients should be monitored for symptoms such as rapid heartbeat, chest pain, unexplained weight loss, or fractures.

Levothyroxine is contraindicated in individuals with untreated adrenal insufficiency, acute myocardial infarction, or uncorrected thyrotoxicosis. Patients with known hypersensitivity to levothyroxine or any of its excipients should also avoid the medication.

Published by

GNH India Pharmaceuticals Limited

Licensed pharmaceutical supplier

Last updated:

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