Levothyroxine
• Trade names:
Eutirox, Levoxyl, Levothroid, Synthroid, Unithroid.
• Classification:
It is a synthetic levoisomer of thyroxine (T4), similar to the
endogenous hormone produced by the thyroid gland.
• Indications:
• Hypothyroidism: 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 in the treatment and prevention
of euthyroid goiters (abnormal enlargement of the thyroid
gland) and in the management of thyroid cancer.
• Mechanism of action:
Thyroxine is de-iodinated to form triiodothyronine (T3) in
the peripheral tissues. T3 enters the cell and binds to
nuclear thyroid hormone receptors, and the hormone-
receptor complex in turn triggers gene expression and
produces proteins required in the regulation of cellular
respiration, thermogenesis, cellular growth and
differentiation, and metabolism of proteins, carbohydrates
and lipids. T4 and T3 also possess cardiac stimulatory
effect.
• Trade names:
Eutirox, Levoxyl, Levothroid, Synthroid, Unithroid.
• Classification:
It is a synthetic levoisomer of thyroxine (T4), similar to the
endogenous hormone produced by the thyroid gland.
• Indications:
• Hypothyroidism: 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 in the treatment and prevention
of euthyroid goiters (abnormal enlargement of the thyroid
gland) and in the management of thyroid cancer.
• Mechanism of action:
Thyroxine is de-iodinated to form triiodothyronine (T3) in
the peripheral tissues. T3 enters the cell and binds to
nuclear thyroid hormone receptors, and the hormone-
receptor complex in turn triggers gene expression and
produces proteins required in the regulation of cellular
respiration, thermogenesis, cellular growth and
differentiation, and metabolism of proteins, carbohydrates
and lipids. T4 and T3 also possess cardiac stimulatory
effect.
