THYROXINE SODIUM

The thyroid hormones act on nearly every cell in the body. They act to increase the basal metabolic rate, affect protein synthesis, help regulate long bone growth (synergy with growth hormone) and neural maturation, and increase the body's sensitivity to catecholamines (such as adrenaline) by permissiveness. The thyroid hormones are essential to proper development and differentiation of all cells of the human body. These hormones also regulate protein, fat, and carbohydrate metabolism, affecting how human cells use energetic compounds. They also stimulate vitamin metabolism. Numerous physiological and pathological stimuli influence thyroid hormone synthesis.

Both T3 and T4 are used to treat thyroid hormone deficiency (hypothyroidism). They are both absorbed well by the gut, so can be given orally. Levothyroxine is the pharmaceutical name of the manufactured version of T4, which is metabolised more slowly than T3 and hence usually only needs once-daily administration. 

C₁₅H₁₁I₄NO₄

LEVOTHYROXINE Available at JAN AUSHADHI STORES 

PRICE

50 mcg- 45 Rs /100 tab

100 mcg-Rs 56/100 tab

Levothyroxine, also known as L-thyroxine, is a manufactured form of the thyroid hormone, THYROXINE (T4). It is used to treat thyroid hormone deficiencyincluding the severe form known as myxedema coma. It may also be used to treat and prevent certain types of thyroid tumors. It is not indicated for weight loss. Levothyroxine is taken by mouth or given by injection into a vein. Maximum effect from a specific dose can take up to six weeks to occur.

Side effects from excessive doses include weight loss, trouble tolerating heat, sweating, anxiety, trouble sleeping, tremor, and fast heart rate. Use is not recommended in people who have had a recent heart attack. Use during pregnancy has been found to be safe. It is recommended that dosing be based on regular measurements of TSH and T4 levels in the blood. Much of the effect of levothyroxine is following its conversion to triiodothyronine (T3).

Levothyroxine was first made in 1927. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. Levothyroxine is available as a generic medication. 

USE

Levothyroxine is typically used to treat hypothyroidism, and is the treatment of choice for people with hypothyroidism, who often require lifelong thyroid hormone therapy. It may also be used to treat goiter via its ability to lower thyroid-stimulating hormone (TSH), a hormone that is considered goiter-inducing. Levothyroxine is also used as interventional therapy in people with nodular thyroid disease or thyroid cancer to suppress thyroid-stimulating hormone (TSH) secretion. A subset of people with hypothyroidism treated with an appropriate dose of levothyroxine will describe continuing symptoms despite TSH levels in the normal range. In these people, further laboratory and clinical evaluation is warranted as they may have another cause for their symptoms. Furthermore, it is important to review their medications and possible dietary supplements as several medications can affect thyroid hormone levels.

Levothyroxine is also used to treat subclinical hypothyroidism which is defined by an elevated TSH level and a normal-range free T4 level without symptoms. Such people may be asymptomatic and whether they should be treated is controversial. One benefit of treating this population with levothyroxine therapy is preventing development of hypothyroidism. As such, it is recommended that treatment should be taken into account for patients with initial TSH levels > 10 mIU/L, people with elevated thyroid peroxidase antibody titers, people with symptoms of hypothyroidism and TSH levels between 5–10 mIU/L, and women who are pregnant or want to become pregnant. Oral dosing for patients with subclinical hypothyroidism is 1 µg/kg/day.

It is also used to treat myxedema coma, which is a severe form of hypothyroidism characterized by mental status changes and hypothermia. As it is a medical emergency with a high mortality rate, it should be treated in the intensive care unit with thyroid hormone replacement and aggressive management of individual organ system complications.