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. 

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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.

BENEFITS OF FERROUS ASCORBATE

      WHO and UNICEF have recommended taking oral iron supplements for adolescents and young children in the countries where 40 percent of anaemia is prevalent in the population. Most of the oral iron formulations are available in the form of ferrous sulphate as well as in the form of ferric compounds consisting of iron polymaltose complex. These iron compounds differ in their safety, bio-availability, cost and side effects.Apart from the different chemical states of iron formulations available in the market, they also exist in different galenic forms.

Clinically, iron salts that are bivalent like ferrous sulphate, ferrous fumarate and ferrous gluconate are widely used than the ferric iron forms. The bio-availability of ferric forms of iron are 3 to 4 times less than the ferrous forms (10 to 15 percent bio-availability). Ferric forms of iron are poorly soluble in alkaline solutions and hence they have to be transformed into ferrous forms before they are absorbed.

Oral iron preparations have followed the conventional‘prolonged-release’ formulation, which improves the toleration capacity of the gastrointestinal tract and enhances the bio-availability. After the ferrous form absorption, iron reaches its maximum in the blood for about 7 hours and stays in that state for 24 hours.

Ferrous ascorbate results from the reaction of ascorbic acid with iron. Iron is absorbed very well in the presence of ascorbic acid, as this compound is known to convert ferric iron into ferrous iron. Ferrous form of iron is soluble at neutral pH and can be absorbed three times higher than the ferric form. Oxidation is prevented by Ascorbic acid, which can thus act as reducing agent as well as maintain the iron in ferrous form. Ferrous ascorbate is known to exist intact inside the gastrointestinal tract due to the stable chelation of iron with ascorbate. This compound does not dissociate due to any of the food inhibitors.  Iron gets absorbed easily in vivo from ferrous ascorbate than from ferrous sulfate. It is found that ferrous ascorbate dissociates in aqueous solution into ascorbate ion and ferrous ion where ascorbate ion acts as a monodentate. Ferrous ascorbate is known to dissociate at pH5. At pH6 to 8, the solubility effect is enhanced by ascorbate, which is beneficial for the absorption of iron from ferrous ascorbate.

A clinical study was conducted comparing the ferrous ascorbate formulation with that of ferrous sulphate in 18 healthy volunteers. The intestinal absorption was not different when measured after 21 days. But, hemoglobin content has come to baseline values in both the groups. Another study by the same research group was conducted in which the bio-availability of trivalent iron form (FeIII hydroxide polymaltose) was compared with the bivalent form (ferrous ascorbate). The iron absorption in the intestines was evaluated in the fasting state by the estimation of plasma iron tolerance curves and whole body iron retention values. The estimation of plasma iron showed lower FeIII content (1.2+/-0.1percent) compared to 43.7+/-7.1percent of ferrous ascorbate. After taking a meal, there was a change in divalent iron absorption than the trivalent iron absorption.

The increase in hemoglobin levels after prescribing 100mg dosage of iron for 28 days was higher in the case of divalent formulations than that of the trivalent formulations. A few other similar studies have proved that divalent form of iron or ferrous ascorbate has greater bio-availability than the trivalent form of iron. Hence, ferrous salts and especially ferrous ascorbate is chosen over other iron forms for preparing the drugs as they are efficient, cost effective and have tolerability.