Novothyrox (levothyroxine sodium)
The following drug information is obtained from various newswires, published
medical journal articles, and medical conference presentations.
Hypothyroidism and suppression of thyroid-stimulating hormone
Novothyrox (levothyroxine sodium) is a thyroid hormone
replacement drug to treat Hypothyroidism and suppression of
thyroid-stimulating hormone. Novothyrox is a tablet administered as
a once-daily therapy. The dose necessary to achieve normal thyroid
hormone levels is dependent on several factors, including, but not
limited to the patient's age, weight, and cardiovascular
status, as well as the nature of the condition being treated. The
average full replacement dose of levothyroxine is approximately 1.7
Adverse reactions associated with levothyroxine therapy are
usually symptoms of hyperthyroidism due to therapeutic
Mechanism of Action
Synthetic levothyroxine (T4) is identical to that
produced naturally in the human thyroid gland.
Thyroid hormone synthesis and secretion is regulated by the
hypothalamic-pituitarythyroid axis. Thyrotropin-releasing hormone
(TRH) released from the hypothalamus stimulates secretion of
thyrotropin-stimulating hormone, TSH, from the anterior pituitary.
TSH, in turn, is the physiologic stimulus for the synthesis and
secretion of thyroid hormones, L-thyroxine (T4) and
L-triiodothyronine (T3), by the thyroid gland.
Circulating serum T3 and T4 levels exert a
feedback effect on both TRH and TSH secretion. When serum
T3 and T4 levels increase, TRH and TSH
secretion decrease. When thyroid hormone levels decrease, TRH and
TSH secretion increase. (From Novothyrox prescription label)
In July 2001, the FDA announced that it would require all
manufacturers of levothyroxine sodium products to submit New Drug
Applications for approval of these products. This guidline applies
to both original and generic forms of the levothyroxine sodium