Levothyroxine Sodium: Brands, Price & Uses in Bangladesh

Levothyroxine Sodium is a synthetic thyroid hormone (T4) used for the following indications:

Established / FDA-approved uses

• Hypothyroidism (primary, secondary/pituitary, and tertiary/hypothalamic): Levothyroxine Sodium is indicated as replacement or supplemental therapy in congenital or acquired hypothyroidism of any etiology, except transient hypothyroidism during the recovery phase of subacute thyroiditis.
• Pituitary TSH suppression: Levothyroxine Sodium is indicated as an adjunct to surgery and radioiodine therapy in the management of well-differentiated thyroid cancer, to suppress TSH secretion.

Uses that are NOT appropriate

• Levothyroxine Sodium is not indicated for treatment of euthyroid goiter or nodular thyroid disease in iodine-sufficient patients, and it is not indicated for suppression of benign thyroid nodules or non-toxic diffuse goiter.
• Levothyroxine Sodium is not indicated for weight loss; in euthyroid patients, doses within the range of daily hormone requirement are ineffective for weight reduction and larger doses may produce serious or life-threatening toxicity, particularly with concurrent use of sympathomimetic amines.

General administration instructions

• Take Levothyroxine Sodium as a single dose, on an empty stomach, 30-60 minutes before breakfast, with a full glass of water.
• Take it consistently at the same time each day to maintain stable blood levels.
• Separate administration by at least 4 hours from calcium supplements, iron supplements, antacids (aluminum/magnesium-containing), bile acid sequestrants (e.g., cholestyramine, colesevelam), sucralfate, and proton pump inhibitors, as these reduce absorption of Levothyroxine Sodium.
• Do not switch between brands or formulations of Levothyroxine Sodium without physician awareness, as bioavailability may differ and require dose re-titration with repeat TSH testing.

Dosing by indication

Renal/hepatic impairment

No well-established specific dose adjustment is required for renal or hepatic impairment; however, dosing should still be individualized and guided by periodic TSH monitoring, as with all patients.

Monitoring

Serum TSH (and free T4 where relevant) should be checked approximately 6-8 weeks after initiation or any dose change, and periodically thereafter (typically every 6-12 months once stable), to guide dose titration.

Adverse effects of Levothyroxine Sodium are generally dose-related and reflect iatrogenic hyperthyroidism from excessive dosing rather than a direct drug toxicity at therapeutic doses:

• Cardiovascular: Palpitations, tachycardia, arrhythmias (including atrial fibrillation, especially in the elderly), angina, increased blood pressure.
• Nervous system: Headache, nervousness, anxiety, insomnia, tremor.
• General/metabolic: Heat intolerance, fever, sweating, weight loss.
• Gastrointestinal: Diarrhea, vomiting, abdominal cramps.
• Musculoskeletal: Muscle weakness, muscle cramps; with long-term overtreatment, reduced bone mineral density.
• Dermatologic: Hair loss (often transient, especially in children in the first months of therapy), flushing.
• Reproductive: Menstrual irregularities.

Most of these effects resolve with dose reduction and represent overtreatment rather than a true idiosyncratic adverse reaction. Rare hypersensitivity reactions (rash, urticaria) can occur, generally related to inactive ingredients rather than the hormone itself.