Levothyroxine is a synthetic form of thyroxine (T4), an endogenous hormone secreted by the thyroid gland, which is converted to its active metabolite, L-triiodothyronine (T3). T4 and T3 bind to thyroid receptor proteins in the cell nucleus and cause metabolic effects through the control of DNA transcription and protein synthesis. Thyroid hormone increases basal metabolic rate, increases utilization and mobilization of glycogen stores, promotes gluconeogenesis; involved in growth development and stimulates protein synthesis.



    Thormon Tablet: Each tablet contains Levothyroxine Sodium USP 50 mcg.


    Hypothyroidism:As replacement or supplemental therapy in congenital or acquired hypothyroidism of any etiology, except transient hypothyroidism during the recovery phase of subacute-thyroiditis.Specific indications: Primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) hypothyroidism and subclinical hypothyroidism.Pituitary TSH Suppression: In the treatment or prevention of various types of euthyroid goiters, subacute or chronic lymphocytic thyroiditis (Hashimoto's thyroiditis), multinodular goiter and, as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer.

Dosage & Administration

    Dosage & Administration:Thormon Tablet should be taken on an empty stomach, preferably before breakfast.Adult Dosage: lnitial starting dose: 25-50 mcg/day, with gradual increments in dose at 6-8 week intervals, as needed. The Levothyroxine Sodium dose is generally adjusted in 12.5-25 mcg increments until the patient with primary hypothyroidism is clinically euthyroid and the serum TSH has normalized.In patients with severe hypothyroidism:Initial dose is 12.5-25 mcg/day with increases of 25 mcg/day every 2-4 weeks, accompanied by clinical and laboratory assessment, until the TSH level is normalized. In patients with secondary (pituitary) or tertiary (hypothalamic) hypothyroidism:Levothyroxine Sodium dose should be titrated until the patient is clinically euthyroid and the serum free - T4 level is restored to the upper half of the normal range. For patients older than 50 years or for patients under 50 years of age with underlying cardiac disease: An initial dose of 25-50 mcg/day is recommended with gradual increments in dose at 6-8 week intervals.Pediatric Dosage: Newborns:The recommended starting dose is 10-15 mcg/kg/day. A lower starting dose should be considered in infants at risk for cardiac failure, and the dose should be increased in 4-6 weeks as needed based on clinical and laboratory response to treatment. In infants with very low (<5 mcg/dL) or undetectable serum T4 concentrations, the recommended initial starting dose is 50 mcg/day of Levothyroxine Sodium. Infants and Children:In children with chronic or severe hypothyroidism, initial dose of 25 mcg/day with increments of 25 mcg every 2-4 weeks until the desired effect is achieved. Hyperactivity in an older child can be minimized if the starting dose is one-fourth of the recommended full replacement dose, and the dose is then increased on a weekly basis by an amount equal to one-fourth the full-recommended replacement dose until the full recommended replacement dose is reached.Daily dose per kg body weight:0-3 months: 10-15 mcg/kg/day, 3-6 months: 8-10 mcg/kg/day, 6-12 months: 6-8 mcg/kg/day, 1-5 years: 5-6 mcg/kg/day, 6-12 years: 4-5 mcg/kg/day, >12 years but growth and puberty incomplete: 2-3 mcg/kg/day, Growth and puberty complete: 1.7 mcg/kg/day. The dose should be adjusted based on clinical response and laboratory parameters.


    This drug is contraindicated for patients who have hypersensitivity to any component of the preparation & in thyrotoxicosis.

Warning & Precautions

    Levothyroxine has a narrow therapeutic index. Careful dosage titration is necessary to avoid the consequences of over- or under-treatment. Exercise caution when administering levothyroxine to patients with cardiovascular disorders and to the elderly in whom there is an increased risk of occult cardiac disease. In these Patients, Levothyroxine therapy should be initiated at lower doses than those recommended in younger individuals or in patients without cardiac disease.

Side effects

    The side effects may include skin rash, pruritus, increased appetite, abdominal cramps, nausea, vomiting, diarrhea, insomnia, restlessness, headache, tremors, seizure, cramps in skeletal muscle, muscular weakness, sweating, flushing, heat intolerance etc.

Drug interaction

    Concurrent use of tri/tetracyclic antidepressants and levothyroxine may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. Toxic effects may include increased risk of cardiac arrhythmias and CNS stimulation; onset of action of tricyclics may be accelerated. Administration of sertraline in patients stabilized on levothyroxine may result in increased levothyroxine requirements. Addition of levothyroxine to antidiabetic or insulin therapy may result in increased antidiabetic agent or insulin requirements. Careful monitoring of diabetic control is recommended, especially when thyroid therapy is started, changed, or discontinued. Serum digitalis glycoside levels may be reduced in hyperthyroidism or when the hypothyroid patient is converted to the euthyroid state. Therapeutic effect of digitalis glycosides may be reduced.

Use in special groups

    Use in pregnancy: USFDA Pregnancy Category A. Studies in women taking levothyroxine sodium during pregnancy have not shown an increased risk of congenital abnormalities. Thormon should be continued during pregnancy.
    Use in nursing mothers : Although thyroid hormones are excreted only minimally in human milk, caution should be exercised when Thormon is administered to a nursing woman. However, adequate replacement doses of levothyroxine are generally needed to maintain normal lactation.


    Thormon Tablet: Each box contains 100 tablets in alu-alu blister pack