Levothyroxine Sodium Tablets are a synthetic form of thyroxine (T4), a hormone naturally produced by the thyroid gland. They are primarily used to treat hypothyroidism, a condition where the thyroid does not produce enough hormones. Levothyroxine helps restore normal metabolic activity by replacing or supplementing the body’s own thyroid hormone levels. It is also used in the management of certain types of goiter and, in some cases, thyroid cancer.

Levothyroxine is converted in the body to triiodothyronine (T3), the more active thyroid hormone, which then binds to thyroid hormone receptors in cells. This regulates gene expression and supports key physiological processes, including metabolism, energy production, brain development, and cardiovascular function. Adequate levels of thyroid hormones are essential for normal growth, neurological development, and overall metabolic balance.

It should be used cautiously in individuals with cardiovascular disease, hypertension, diabetes, and osteoporosis. Overreplacement can lead to symptoms of hyperthyroidism and increase the risk of heart complications, especially in older adults.

Levothyroxine has numerous drug interactions. It may have reduced absorption when taken with calcium, iron, antacids, or certain cholesterol-lowering agents (like cholestyramine or colesevelam). It may also interact with anticoagulants (e.g., warfarin), insulin, and oral diabetes medications, potentially altering their effects.

When dosed appropriately, levothyroxine is generally well tolerated. However, if the dose is too high, symptoms of hyperthyroidism can occur, including palpitations, anxiety, insomnia, weight loss, increased appetite, sweating, tremors, and heat intolerance. In rare cases, allergic reactions or hair thinning may occur, particularly at the start of therapy. Serious side effects are usually a result of overdosage or poor dose adjustment.

Levothyroxine is considered safe and essential during pregnancy, as untreated hypothyroidism can lead to miscarriage, preterm birth, and impaired fetal development. Dosing requirements often increase during pregnancy, and close monitoring of thyroid hormone levels is necessary. It is also safe to use while breastfeeding, as only minimal amounts are excreted in breast milk and do not adversely affect the nursing infant.

Store this medication at 68°F to 77°F (20°C to 25°C) and away from heat, moisture and light. Keep all medicine out of the reach of children. Throw away any unused medicine after the beyond use date. Do not flush unused medications or pour down a sink or drain.

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