Synthroid

Synthroid Information

Generic Name: Levothyroxine Sodium

Other Common Names: Eutirox, Sintrocid

Synthroid (levothyroxine sodium) is intended to replace a hormone that is normally produced by thethyroid gland. It is generally taken for life, except in cases of temporary hypothyroidism associated with an inflammation of the thyroid gland.

Since the mechanisms affected by Synthroid also affect the metabolism, it has been additionally used as a weigh-loss drug. The Pharma-Help Team discourages this.

Synthroid is prescribed as:

a replacement or supplemental therapy in patients of any age or state (including pregnancy) with hypothyroidism of any etiology except transient hypothyroidism during the recovery phase of subacute thyroiditis: primary hypothyroidism resulting from thyroid dysfunction, primary atrophy, or partial or total absence of the thyroid gland, or from the effects of surgery, radiation or drugs, with or without the presence of goiter, including subclinical hypothyroidism; secondary (pituitary) hypothyroidism; and tertiary (hypothalamic) hypothyroidism. Levothyroxine sodium injection can be used intravenously when rapid repletion is required, and either intravenously or intramuscularly when the oral route is precluded.
a pituitary TSH supressant in the treatment or prevention of various types of euthyroid goiters, including thyroid nodules, subacute or chronic lymphocytic thydroiditis (Hashimoto's), multinodular goiter, and in conjunction with surgery and radioactive iodine therapy in the management of thyrotropin-dependent well-differentiated papillary or follicular carcinoma of the thyroid.

How Does Synthroid Work?

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.

How To Take Synthroid and Synthroid Dosage and Administration

The dosage and rate of administration of levothyroxine sodium is determined by the indication, and must in every case be individualized according to patient response and laboratory findings.

Synthroid comes in the following forms:

Synthroid Tablets: Synthroid tablets are round, color coded, scored, and debossed with FLINT and potency:

25 mcg, orange
50 mcg, white
75 mcg, violet
88 mcg, olive
100 mcg, yellow
112 mcg, rose
125 mcg, brown
150 mcg, blue
175 mcg, lilac
200 mcg, pink
300 mcg, green

Synthroid Injection: Synthroid injection is a lyophilized powder. It is supplied in color coded vials as follows:

200 mcg, gray
500 mcg, yellow

If you suspect a Synthroid Overdose

Excessive doses of levothyroxine sodium result in a hypermetabolic state indistinguishable from thyrotoxicosis of endogenous (thyroid-caused) origin.

Signs and symptoms of thyrotoxicosis include:

weight loss
increased appetite
palpitations
nervousness
diarrhea
abdominal cramps
sweating
tachycardia
increased pulse and blood pressure
cardiac arrhythmias
tremors
insomnia
heat intolerance
fever
menstrual irregularities.

Symptoms are not always evident or may not appear until several days after ingestion.

Temporarily discontinue the dosage should this occur.

Synthroid Ingredients and Composition

Synthroid Side Effects

Synthroid Precautions and Contraindications

Before or at any time while using levothyroxine sodium, you should tell your doctor if you are allergic to any foods or medicines, are pregnant or intend to become pregnant, are breast-feeding, are taking or start taking any other prescription or non-prescription (OTC) medications, or have any other medical problems (especially hardening of the arteries, heart disease, high blood pressure, or history of thyroid, adrenal or pituitary gland problems).

You should inform your doctor or dentist that you are taking levothyroxine sodium before having any kind of surgery.

You should notify your doctor if you experience any of the following symptoms:

chest pain
shortness of breath
hives or skin rash
rapid or irregular heartbeat
headache
irritability
nervousness
sleeplessness
diarrhea
excessive sweating
heat intolerance
changes in appetite
vomiting
weight gain or loss
changes in menstrual periods
fever
hand tremors
leg cramps

If you have diabetes, your dose of insulin or oral antidiabetic agent may need to be changed after starting levothyroxine sodium. You should monitor your blood or urinary glucose levels as directed by your doctor and report any changes to your doctor immediately.

Taking Synthroid during Pregnancy or Breast-feeding

You should notify your doctor if you become pregnant while taking levothyroxine sodium. Your dose of this medicine will likely have to be increased while you are pregnant.

Minimal amounts of thyroid hormones are excreted in human milk. Thyroid hormones are not associated with serious adverse reactions and do not have known tumorigenic potential. While caution should be exercised when levothyroxine sodium is administered to a nursing woman, adequate replacement doses of levothyroxine sodium are generally needed to maintain normal lactation.

Synthroid Experiences and Results

It may take a few weeks for levothyroxine sodium to begin working. Until it begins working, you may not notice any change in your symptoms.

Storing Synthroid

Store at controlled room temperature 15°-30°C (59°-86°F).