1.SYNTHROID HISTORY
(How was Synthroid discovered?)

Synthroid is the brand name used by Abbott Laboratories for Levothyroxine sodium (T4, a synthetic thyroid hormone) product. Levothyroxine is the basic T4 thyroid hormone responsible for metabolism. Patients who suffer from hypothyroidism, either for endogenous disease or after radioactive iodine ablation or thyroid resection, require exogenous thyroid hormone, and Synthroid is the most prescribed brand of T4.

Synthroid was marketed in 1955, but was not FDA approved at that time as it was considered "generally regarded safe". In the 1990s, in response to various complaints, all Levothyroxine preparations were required to undergo the formal FDA approval process.

The FDA approved Synthroid on 24th July 2002.

Abbott Laboratories is a pharmaceuticals and health care company. It has around 56,000 employees and operates in 130 countries. The corporate headquarters are in Abbott Park, IL, a northern suburb of Chicago, IL, near its manufacturing center in North Chicago, Illinois. In 2001, Abbott acquired Knoll, the phamaceutical division of BASF. In 2003, Abbott had nearly $20 billion in sales.

In 2004, Abbott spun off its hospital products division into a new 14,000 employee company named Hospira.

In 1985, the company developed the first HIV blood-screening test. The company's drug portfolio includes Humira, a drug for rheumatoid arthritis, Norvir, a treatment for HIV, Depakote, an anticonvulsant drug, Synthroid, a synthetic thyroid hormone, and Ensure for adult nutrition.

Abbott also has a broad range of diagnostics and immunoassay products. 

2.SYNTHROID FACTS

The thyroid gland produces and releases two hormones: thyroxine and liothyronine. In other areas of the body, thyroxine is subsequently converted into liothyronine, which is a more active form of thyroxine. These hormones are responsible for maintaining a normal rate of metabolism in the body.

When the thyroid gland is unable to produce normal amounts of thyroxine, the level of thyroid hormones in the blood decreases (hypothyroidism). This results in a reduced rate of metabolism, leading to symptoms such as weight gain, intolerance to cold and tiredness.

Synthroid tablets are given to replace the thyroxine that would normally be produced naturally by the thyroid gland. 

3.ABOUT SYNTHROID MEDICATION

The thyroid gland makes, stores, and releases two hormones �?T4 (thyroxine) and T3 (triiodothyronine). Thyroid hormones control the rate at which every part of your body works. This is called your metabolism.

The thyroid gland is controlled by the pituitary gland (a gland in your brain). The pituitary gland makes thyroid-stimulating hormone (TSH).

If there is not enough thyroid hormone in the bloodstream, the body's metabolism slows down. This is called hypothyroidism (underactive thyroid). If there is too much thyroid hormone, your metabolism speeds up. This is called hyperthyroidism (overactive thyroid). 

Thyroid Disease
The thyroid is a gland that controls key functions of your body. Disease of the thyroid gland can affect nearly every organ in your body and harm your health. Thyroid disease is eight times more likely to occur in women than in men. In some women it occurs during or after pregnancy. In most cases, treatment of Thyroid disease is safe and simple. 

Your doctor will use tests to help find the exact cause of the problem. You may have:

• Blood tests
• Ultrasound exam (during pregnancy)
• Thyroid scan

Hypothyroidism

Hypothyroidism occurs when the thyroid gland is not working hard enough.

Causes

The causes of Hypothyroidism are

• Inflammation of the thyroid gland, which leaves a large percentage of the cells of the thyroid.
• Hashimoto's Thyroiditis : The most common cause of hypothyroidism is an inherited condition called Hashimoto's thyroiditis. This condition is named after Dr. Hakaru Hashimoto who first described it in 1912. In this condition, the thyroid gland is usually enlarged (goiter) and has a decreased ability to make thyroid hormones. Hashimoto's is an autoimmune disease in which the body's immune system inappropriately attacks the thyroid tissue.

• If the total mass of thyroid producing cells left within the body are not enough to meet the needs of the body, the patient will develop hypothyroidism. This can develop after partial surgical removal of the thyroid gland.
• Lymphocytic Thyroiditis following hyperthyroidism : Thyroiditis refers to inflammation of the thyroid gland. When the inflammation is caused by a particular type of white blood cell known as a lymphocyte, the condition is referred to as lymphocytic thyroiditis. This condition is particularly common after pregnancy.
• Thyroid Destruction (from radioactive iodine or surgery).
• Pituitary or Hypothalamic Disease
• Medications that are used to treat an over-active thyroid (hyperthyroidism) may actually cause hypothyroidism. The psychiatric medication, lithium, is also known to alter thyroid function and cause hypothyroidism.
• Severe Iodine Deficiency : In areas of the world where there is an iodine deficiency in the diet, severe hypothyroidism can be seen in 5 to 15% of the population. Examples of these areas include Zaire, Ecuador, India, and Chile. Severe iodine deficiency is also seen in remote mountain areas such as the Andes and the Himalayas. Since the addition of iodine to table salt and to bread, iodine deficiency is rarely seen in the United States.

Symptoms
The symptoms of hypothyroidism are slow to develop. Common symptoms of hypothyroidism are:

• Fatigue or weakness
• Weight gain
• Decreased appetite
• Change in menstrual periods
• Loss of sex drive
• Feeling cold when others don't
• Constipation
• Muscle aches
• Puffiness around the eyes
• Brittle nails
• Hair loss

If your lab tests show that the hormone levels are normal, some other condition may be causing your symptoms.

Treatment

In most cases, hypothyroidism is treated with medication that contains thyroid hormone like Synthroid.

Hyperthyroidism

Hyperthyroidism results when the thyroid gland is making too much thyroid hormone. This causes your metabolism to speed up.

Causes
The most common cause of hyperthyroidism is a disorder known as Graves' disease. It most often affects women between the ages of 20 and 40 years.

Symptoms
The more common symptoms of hyperthyroidism are:

• Fatigue
• Weight loss
• Nervousness
• Rapid heart beat
• Increased sweating
• Feeling hot when others don't
• Changes in menstrual periods
• More frequent bowel movements
• Tremors

Treatment

Treatment for hyperthyroidism will lower the amount of thyroid hormone and relieve your symptoms.

Thyroid Nodules

A nodule is a lump in the thyroid gland.

Nodules may be further examined by a procedure known as fine needle aspiration or biopsy.

Treatment Of Thyroid Disease

Abnormalities of thyroid function (hyper or hypothyroidism) are usually treated medically. If there is insufficient production of thyroid hormone, this may be given in a form of a thyroid hormone pill taken daily. Hyperthyroidism is treated mostly by medical means, but occasionally it may require the surgical removal of the thyroid gland.

If there is a lump of the thyroid or a diffused enlargement (goiter), your doctor will propose a treatment plan based on the examination and your test results. Most thyroid "lumps" are benign. Often they may be treated with thyroid hormone, and this is called "suppression" therapy. The object of this treatment is to attempt shrinkage of the mass over time, usually three-six months. If the lump continues to grow during treatment when you are taking the medication, most doctors will recommend removal of the affected lump.

If the fine needle aspiration is reported as suspicious for or suggestive of cancer, then thyroid surgery is required.

are rare. They include bleeding, a hoarse voice, difficulty swallowing, numbness of the skin on the neck, and low blood calcium. Most complications go away after a few weeks. Patients who have all of their thyroid gland removed have a higher risk of low blood calcium post-operatively.

Patients who have thyroid surgery may be required to take thyroid medication to replace thyroid hormones after surgery. Some patients may need to take calcium replacement if their blood calcium is low. This will depend on how much thyroid gland remains, and what was found during surgery. If you have any questions about thyroid surgery, ask your doctor and he or she will answer them in detail.  

4.SYNTHROID EFFECTIVENESS
(When is Synthroid best taken?)

The synthesis and secretion of the major thyroid hormones, L-thyroxine (T4) and L-triiodothyronine (T3), from the normally functioning thyroid gland are regulated by complex feedback mechanisms of the hypothalamic-pituitary-thyroid axis. The thyroid gland is stimulated to secrete thyroid hormones by the action of thyrotropin (thyroid stimulating hormone, TSH) which is produced in the anterior pituitary gland. TSH secretion is in turn controlled by thyrotropin-releasing hormone (TRH) produced in the hypothalamus, circulating thyroid hormones, and possibly other mechanisms. thyroid hormones circulating in the blood act as feedback inhibitors of both TSH and TRH secretion. Thus, when serum concentrations of T3 and T4 are increased, secretion of TSH and TRH is increased. Administration of exogenous thyroid hormones to euthyroid individuals results in suppression of endogenous thyroid hormone secretion.

The mechanisms by which thyroid hormones exert their physiologic actions have not been completely elucidated. T4 and T3 are transported into cells by passive and active mechanisms. T3 in cell cytoplasm and T3 generated from T4 within the cell diffuse into the nucleus and bind to thyroid receptor proteins, which appear to be primarily attached to DNA. Receptor binding leads to activation or repression of DNA transcription, thereby altering the amounts of mRNA and resultant proteins. Changes in protein concentrations are responsible for the metabolic changes observed in organs and tissues.

Thyroid hormones enhance oxygen consumption of most body tissues and increase the basal metabolic rate and metabolism of carbohydrates, lipids, and proteins. Thus, they exert a profound influence on every organ system and are of particular importance in the development of the central nervous system. Thyroid hormones also appear to have direct effects on tissues, such as increased myocardial contractility and decreased systemic vascular resistance.

The physiologic effects of thyroid hormones are produced primarily by T3, a large portion of which is derived from the from the deiodination of T4 in peripheral tissues. About 70 to 90 percent of peripheral T3 is produced by monodeoidination of T4 at the 5' position (outer ring). Peripheral monodeiodination of T4 at the 5 position (inner ring) results in the formation of reverse triiodothyronine (rT3), which is calorigenically inactive.

Few clinical studies have evaluated the kinetics of orally administered Synthroid (T4) . In animals, the most active sites of absorption appear to be the proximal and mid-jejunum. Synthroid is not absorbed from the stomach and little, if any, drug is absorbed from the duodenum. There seems to be no absorption of Synthroid from the distal colon in animals. A number of human studies have confirmed the importance of an intact jejunum and ileum for Synthroid absorption and have shown some absorption from the duodenum. Studies involving radioiodinated T4 fecal tracer excretion methods, equilibration, and AUC methods have shown that absorption varies from 48 to 80 percent of the administered dose. The extent of absorption is increased in the fasting state and decreased in malabsorption syndromes, such as sprue. Absorption may also decrease with age. The degree of T4 absorption is dependent on the product formulation as well as on the character of the intestinal contents, including plasma protein and soluble dietary factors, which bind thyroid hormone making it unavailable for diffusion. Decreased absorption may result from administration of infant soybean formula, ferrous sulfate, sodium polystyrene sulfonate, aluminum hydroxide sucralfate, or bile acid sequestrants.

Distribution of thyroid hormones in human body tissues and fluids has not been fully elucidated. More than 99% of circulating hormones is bound to serum proteins, including thyroxine-binding globulin (TBG), thyroxine-binding prealbumin (TBPA), and albumin (TBA).