Cytomel

Cytomel is a prescription -based medicine used to treat low thyroid hormone symptoms (hypothyroidism) and enlarged thyroid gland (nontoxic goose), mixedem and myxedema coma. Cytomel can be used alone or together with other drugs.

Cytomel belongs to a class of drugs called thyroid products.

What are the possible side effects of Cytomel?

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The cytomel can cause serious side effects, including:

• headache,
• irritability,
• Sleep problems,
• nervousness,
• Increased sweating,
• heat intolerance,
• diarrhea and
• menstrual changes

Get medical care immediately if you have any of the symptoms listed above.

The most common side effects of Cytomel include:

Tell the doctor if you have any side effect that bothers you or does not disappear.

These are not all possible side effects of cytomel. For more information, consult your doctor or pharmacist.

Ask your doctor for medical advice on side effects. You can report side effects to FDA at 1-800-FDA-1088.

DESCRIPTION

Thyroid hormone drugs are natural or synthetic preparations containing tetraiodothyronin (T4, levothyroxine) sodium or triiodothyronine (T3, liotonin) sodium or both. T4 and T3 are produced in the human thyroid gland by iodine and coupling thyrozine amino acids. T4 contains four iodine atoms and is formed by coupling two diodothyrosine molecules (DIT). T3 contains three iodine atoms and is formed by coupling a dit molecule with a molecule of monoiodothyrosine (MIT). Both hormones are stored in thyroglobulin’s thyroid colloid.

Thyroid hormonal preparations belong to two categories: (1) natural hormonal preparations derived from animal thyroid and (2) synthetic preparations. Natural preparations include dehydrated thyroid and thyroglobulin. Dehydrated thyroid is derived from domesticated animals that are used for feed by humans (either beef or pork), and thyroglobulin is derived from pork thyroid glands. Pharmacopoeia of the United States (USP) has standardized the total iodine content of natural preparations. The thyroid USP contains no less than (NLT) 0.17% and no more than (NMT) 0.23% iodine, and thyroglobulin contains no less than (NLT) 0.7% iod. Iodine content is just an indirect indicator of true hormonal biological activity.

Cytomel tablets (liotonin sodium) contain liotonin (L-triiodothyronine or LT3), a synthetic form of a natural thyroid hormone and are available as sodium salt.

Structural and empirical formulas and molecular weight of sodic liotonin are given below.

Lyotironin sodium

L-thyrosine, O- (4-hydroxy-3-iodophenil) -3.5-Diiodo-, monosodic salt

Twenty-five micrograms of liotonin are equivalent to about 1 grain of dehydrated thyroid or thyroglobulin and 0.1 mg of L-thyroxine.

Each round tablet, white to almost white, cytome (sodium liotironin) contains liotironin sodium equivalent to liotonin, as follows: 5 MCG KPI and 115; 25 mcg scored and marked KPI and 116; 50 mcg scored and scored KPI and 117. Inactive ingredients consist of calcium sulfate, gelatin, corn starch, stearic acid, sucrose and talc.

Directions

Thyroid hormone drugs are indicated:

As a substitution or additional therapy in patients with hypothyroidism of any etiology, except for transient hypothyroidism during the subacute thyroiditis phase. This category includes creatinism, mixedemus and ordinary hypothyroidism in patients of any age (children, adults, elderly) or state (including pregnancy); The primary hypothyroidism resulting from the functional deficiency, the primary atrophy, the partial or total absence of the thyroid gland or the effects of surgery, radiation or drugs, with or without the presence of the goose; and secondary hypothyroidism (pituitary) or tertiary (hypothalamic) (see Warnings ).

As inhibitors of the pituitary thyroid stimulator (TSH), in the treatment or prevention of different types of eutyroid guards, including thyroid nodules, subacute or chronic lymphocyte thyroiditis (Hashimoto) and multinodular goose.

As diagnostic agents in suppression tests to differentiate easily suspected hyperthyroidism or thyroid autonomy.

Cytomal tablets (liotonin sodium) can be used in allergic patients in dehydrated thyroid or thyroid extract derived from pork or beef.

Dosage and administration

The dosage of thyroid hormones is determined by the indication and must in each case individualized according to the patient’s response and the laboratory results.

Cytomal tablets (liotonin sodium) are intended for oral administration; Dosage is recommended once a day. Although Sodium liotonin has a rapid interruption, its metabolic effects persist a few days after discontinuation of treatment.

Easy hypothyroidism

The recommended initial dose is 25 mcg per day. The daily dose can then be increased by up to 25 mcg every 1 or 2 weeks. The usual maintenance dose is 25 to 75 mcg daily.

The rapid onset and dissipation of the action of sodic (T3) liotonins, compared to levothyroxine sodium (T4), caused some doctors to prefer its use in patients who may be more sensitive to the unfavorable effects of thyroid medication. However, the wide oscillations of serum t levels that follow its administration and the possibility of more pronounced cardiovascular side effects tend to counterbalance the declared advantages.

Cytomel tablets (liotironin sodium) can be used in preference levothyroxine (T4) during radioisotopic scanning procedures, because induction of hypothyroidism in these cases is shorter and may have a shorter duration. May also be preferred when the peripheral conversion of T4 is suspected in T3.

myxedema

The recommended initial dose is 5 mcg per day. This can be increased by 5 to 10 mcg daily every 1 or 2 weeks. When reaching 25 mcg daily, the dose can be increased by 5 to 25 mcg every 1 or 2 weeks until a satisfactory therapeutic response is obtained. The usual maintenance dose is 50 to 100 mcg per day.

Myxedema coma

Mixedem coma is usually precipitated in the long -term hypothyroid patient by intercurrent diseases or drugs such as sedatives and anesthetics and should be considered a medical emergency.

It is recommended to use an intravenous preparation of sodium liotironin in mixed / pre -mixedem.

Congenital hypothyroidism

The recommended initial dose is 5 mcg daily with an increase of 5 mcg every 3 to 4 days until the desired response is obtained. Infants a few months old may require only 20 mcg daily for maintenance. At 1 year, 50 mcg per day may be required. Over 3 years, a full dose for adults may be required (see PCT Precautions ; Pediatric use ).

Simple (non -toxic) goose

The recommended initial dose is 5 mcg per day. This dose can be increased by 5 to 10 mcg daily every 1 or 2 weeks. When reaching 25 mcg daily, the dose can be increased each week or two by 12.5 or 25 mcg. The usual maintenance dose is 75 mcg daily.

To the elderly or in children and teenagers, The therapy should be initiated by 5 mcg daily and raised only with 5 mcg steps at recommended intervals.

When you switch a patient on cytome (liotonin sodium) From thyroid, l-thyroxine or thyroglobulin, stop the other drugs, initiate Cytomel to a small dose and gradually increase the patient’s response. When selecting an initial dose, keep in mind that this medicine has a rapid onset of action and that the residual effects of the other thyroid preparation can persist within the first few weeks of therapy.

Thyroid suppression therapy

Administration of thyroid hormone in doses higher than those physiologically produced by the gland results in suppression of endogenous hormone production. This is the basis of the thyroid suppression test and is used as a help in diagnosing patients with signs of easy hyperthyroidism in which the base laboratory tests seem or to demonstrate the autonomy of the thyroid gland in patients with Graves ophthalmopathy. Absorption is determined before and after the administration of exogenous hormone. A 50% or higher suppression of absorption indicates a normal thyroid-pituitary axis and thus excludes thyroid gland autonomy.

Cytomal tablets (liotonin sodium) are given in doses of 75 to 100 mcg / day for 7 days, and radioactive iodine absorption is determined before and after hormone administration. If thyroid function is under normal control, radioactive iodine absorption will decrease significantly after treatment. Cytomal tablets (liotonin sodium) should be administered with caution to patients in whom there is a strong suspicion of autonomy of the thyroid gland, given that the effects of exogenous hormone will be additive to the endogenous source.

How to provide

Cytomel tablets (Lyotironin sodium) : 5 mcg in 100 bottles; 25 mcg in 100 bottles; and 50 mcg in 100 bottles.

5 mcg 100: Ndc 60793-115-01
25 mcg 100: Ndc 60793-116-01
50 mcg 100: Ndc 60793-117-01

Store between 15 ° and 30 ° C (59 ° and 86 ° F).

Distributed by: Pfizer Inc, New York, 10017. Reviewed: June 2016

Side effects and drug interactions

SIDE EFFECTS

Adverse reactions, other than those indicating hyperthyroidism due to therapeutic overdose, either initially or during the maintenance period are rare (see overdose ). In rare cases, cutaneous allergic reactions with Cytomel tablets (Liotonin sodium) have been reported.

Drug interactions

Oral anticoagulants

Thyroid hormones seem to increase the catabolism of coagulation factors dependent on vitamin K. If oral anticoagulants are also administered, compensatory increases in coagulation factor synthesis are affected. Patients stabilized on oral anticoagulants that are found to require thyroid substitution therapy should be very carefully supervised at the beginning of thyroid. If a patient is truly hypothyroid, it is likely that an anticoagulant dose reduction is required. No special precaution seems to be required when oral anticoagulant therapy begins in a patient already stabilized at thyroid maintenance replacement therapy.

Insulin or oral hypoglycemia

Initiation of thyroid substitution therapy can cause increased insulin or hypoglycemia needs. The observed effects are poorly understood and depend on a variety of factors, such as dose and type of thyroid preparations and the patient’s endocrine condition. Patients who are given insulin or oral hypoglycemia should be carefully supervised during the initiation of thyroid substitution therapy.

Cholestyramine

Colestiramine is linked to both T4 and T3 in the intestine, thus affecting the absorption of these thyroid hormones. In vitro Studies indicate that binding is not easily removed. Therefore, 4 to 5 hours must be passed between the administration of cholestyramine and thyroid hormones.

Estrogen, oral contraceptives

Estrogens tend to increase serum globulin linking thyroxine (TBG). In a patient with a non -functional thyroid gland receiving thyroid substitution therapy, free levothyroxine can be low when estrogen is initiated, thus increasing thyroid requirements. However, if the patient’s thyroid gland has sufficient function, decreased free thyroxine will lead to a compensatory increase in thyroid production. Therefore, patients without a functional thyroid gland, undergoing treatment of thyroid substitution, may need to increase their thyroid dose if estrogen or contraceptives containing estrogen.

Tricyclic antidepressants

The use of thyroid products with imipramine and other tricyclic antidepressants can increase the sensitivity of the receptors and increase the antidepressant activity; Transient cardiac arrhythmias were observed. The thyroid hormone activity can also be improved.

Digital

Thyroid preparations can enhance the toxic effects of digital. Thyroid hormonal replacement increases the metabolic rate, which requires an increase in digital dose.

ketamine

When administered to patients on a thyroid preparation, this parenteral anesthetic can cause hypertension and tachycardia. Use with caution and be prepared to treat hypertension, if necessary.

vasopressor

Thyroxine increases the adrenergic effect of catecholamines such as epinephrine and norepinephrine. Therefore, injecting these agents in patients who are given thyroid preparations increases the risk of precipitation of coronary insufficiency, especially in patients with coronary heart disease. Careful observation is required.

Drug and Laboratory Testing Interactions

It is known that the following drugs or portions interfere with laboratory tests performed in patients treated with thyroid hormones: androgens, corticosteroids, estrogens, oral contraceptives containing estrogen, preparations containing iodine and numerous salicylate preparations.

TBG concentration changes should be taken into account when interpreting T4 and T3 values. In such cases the (free) illegal hormone should be measured. Pregnancy, estrogens and oral contraceptives containing estrogen increase TBG concentrations. TBG may also be increased during infectious hepatitis. Decreases in TBG concentrations are observed in nephrosis, acromegaly and after androgen therapy or corticosteroids. Family globulinemia that bind hyper- or hypo-thyroxine have been described. The incidence of TBG deficit is about 1 in 9000. The binding of thyroxine -binding prealxumin (TBPA) is inhibited by salicylates.

Medicinal or dietary iodine interferes with all in vivo Radioactive iodine absorption tests, producing low absorption that may not reflect a real decrease in hormonal synthesis.

The persistence of the clinical and laboratory evidence of hypothyroidism, despite the proper replacement of the doses, indicates either the poor compliance of the patient, the weak absorption, the excessive fecal loss or the inactivity of the preparation. Intracellular resistance to thyroid hormone is quite rare.

Warnings

Drugs with thyroid hormonal activity, alone or together with other therapeutic agents, have been used for the treatment of obesity. In patients with eutyroidia, doses in the range of daily hormonal requirements are ineffective to reduce weight. Higher doses can produce severe or even dangerous toxicity manifestations for life, especially when administered in combination with sympathomimetic amines, such as those used for their anorectic effects.

The use of thyroid hormones in obesity therapy, alone or combined with other drugs, is undue and has proven to be inefficient. Nor are their use justified for the treatment of male or female infertility unless this condition is accompanied by hypothyroidism.

Thyroid hormones should be used with great caution in a number of circumstances in which the integrity of the cardiovascular system is suspected, especially of the coronary arteries. These include patients with angina pectoral or elderly, at which there is a higher probability of occult cardiac disease. In these patients, sodium therapy with Liotonin should be initiated with low doses, taking into account the relatively rapid onset of its action. The initial dose of cytome tablets (liotonin sodium) is 5 mcg per day and should be increased by maximum 5 mcg in intervals of 2 weeks. When, in such patients, an eutyroid condition can only be reached to the detriment of a cardiovascular disease, the dose of thyroid hormone should be reduced.

Morphological hypogonadism and nephrosis should be excluded before administration of the drug. If there is hypopituitarism, adrenal deficiency should be corrected before the drug starts. Mixedematous patients are very sensitive to thyroid; Dosage should start at a very low and gradually increased level.

Severe and prolonged hypothyroidism can lead to a low level of adrenocortical activity in proportion to low metabolic condition. When thyroid substitution therapy is administered, metabolism increases by a higher rate than adrenal activity. This can precipitate adrenocortical insufficiency. Therefore, in severe and prolonged hypothyroidism, additional adrenocortical steroids may be required. In rare cases, the administration of thyroid hormone may precipitate a state of hyperthyroidism or aggravate existing hyperthyroidism.

Precautions

general

Thyroid hormone therapy in patients with concomitant diabetes or insipid or adrenal cortical insufficiency aggravates the intensity of their symptoms. Appropriate adjustments of different therapeutic measures aimed at these concomitant endocrine diseases are required.

Mixedem comedy therapy requires simultaneous glucocorticoid administration.

Hypothyroidism decreases, and hyperthyroidism increases the sensitivity to oral anticoagulants. Prothrombin time should be closely monitored in patients treated with thyroid on oral anticoagulants and the dose of these last agents should be adjusted based on frequent prothrombin time. In infants, excessive doses of thyroid hormonal preparations can cause craniosynosis.

Laboratory tests

Treatment of patients with thyroid hormones require periodic evaluation of thyroid status by appropriate laboratory tests, in addition to complete clinical evaluation. The TSH suppression test can be used to test the effectiveness of any thyroid preparation, taking into account the relative insensitivity of the baby’s pituitary gland to the negative feedback effect of thyroid hormones. Serum t4 levels can be used to test the effectiveness of all thyroid drug. When T4 total serum is low but TSH is normal, a specific test is justified to evaluate illegat (free) t4 levels. Specific measurements of T4 and T3 by competitive binding of protein or radioimunotest are not influenced by blood or inorganic iodine levels and have essentially replaced the older tests of thyroid hormone measurements, ie PBI, EIB and T4 through the column.

Carcinogenesis, mutagenesis, impairment of fertility

An apparent association between prolonged thyroid therapy and breast cancer has not been confirmed, and patients with thyroid for set indications should not interrupt the therapy. No long-term confirmation studies have been carried out in animals to assess carcinogenic potential, mutagenity or impairment of fertility, either in men or women.

Task

Category A

Thyroid hormones do not easily cross the placental barrier. Clinical experience so far does not indicate any adverse effect on fetus when thyroid hormones are administered to pregnant women. Based on current knowledge, thyroid substitution therapy in hypothyroid women should not be interrupted during pregnancy.

Mothers who are breastfeeding

Minimum amounts of thyroid hormones are excreted in human milk. The thyroid is not associated with serious side effects and does not have a known tumorigen potential. However, caution should be made when the thyroid is administered to a breastfeeding woman.

Geriatric use

The clinical studies of sodic liotonin did not include a sufficient number of subjects over 65 to determine if they are responsible for younger subjects. Other reported clinical experiences have not identified differences in the answers between the elderly and the youngest. Generally, the dose selection for an elderly patient must be cautious, usually from the low end of the dosing range, reflecting the higher frequency of the hepatic, renal or cardiac function and concomitant disease or other drug therapies. It is known that this medicine is substantially excreted by the kidneys, and the risk of toxic reactions to this medicine may be higher in patients with renal failure. As elderly patients are more likely to have low renal function, the dose selection should be paid and it may be useful to monitor renal function.

Pediatric use

Pregnant mothers provide little thyroid hormone to fetus. The incidence of congenital hypothyroidism is relatively large (1: 4000), and the hypothyroid fetus would not get any benefit from the small amounts of hormones that cross the placental barrier. Routine determinations of T and / or TSH serum are recommended in newborns, given the harmful effects of thyroid deficit on growth and development.

The treatment should be initiated immediately after diagnosis and maintained for life, unless transient hypothyroidism is suspected, in which case the therapy can be interrupted for 2 to 8 weeks after the age of 3 to reassess the condition. Treatment cessation is justified in patients who have maintained a normal TSH in these 2 to 8 weeks.

Overdose and contraindications

overdose

Signs and symptoms

Headache, irritability, nervousness, sweating, arrhythmia (including tachycardia), increased intestinal motility and menstrual irregularities. Angina pectoral or congestive heart failure may be induced or aggravated. The shock can also develop. Massive overdose can lead to symptoms similar to thyroid storm. Excessive chronic dosage will produce signs and symptoms of hyperthyroidism.

Treatment of overdose

Dosage should be reduced or treatment should be temporarily discontinued if signs and symptoms of overdose occur. Treatment can be reinstated to a lower dose. In normal individuals, normal hypothalamic-thyroidaxic function is restored in 6 to 8 weeks after thyroid suppression.

The treatment of acute overdose with massive thyroid hormones aims to reduce gastrointestinal absorption of drugs and to counteract central and peripheral effects, mainly those with increased sympathetic activity. Vomiting can be initially induced if an additional gastrointestinal absorption can be reasonably prevented and except contraindications, such as coma, seizures or loss of softening reflex. Treatment is symptomatic and supporting. Oxygen can be given and ventilation can be maintained. Cardiac glycosides can be indicated if congestive heart failure develops. If necessary, measures to combat fever, hypoglycemia or loss of liquids need to be instituted. Antiadrenergic agents, especially propranolol, have been used advantageously in the treatment of increased sympathetic activity. Propranolol can be administered intravenously at a dose of 1 to 3 mg over a 10 -minute period or orally, between 80 and 160 mg / day, especially when there are no contraindications for its use.

Contraindications

Thyroid hormonal preparations are generally contraindicated in patients with diagnosed adrenal cortical failure, but still uncorrected, untreated thyrotoxicosis and apparent hypersensitivity to any of their active or foreign constituents. However, there is no well -documented evidence from the specialized literature on true allergic or idiosyncratic reactions to thyroid hormone.

Clinical pharmacology

The mechanisms by which thyroid hormones exercise their physiological action are not well understood. These hormones increase the consumption of oxygen by most body tissues, increase the basal metabolic rate and metabolism of carbohydrates, lipids and proteins. Thus, they exert a deep influence on each system of organ organs and are of particular importance in the development of the central nervous system.

Pharmacokinetics

Since liotonin sodium (T3) is not firmly linked to serum proteins, it is easily available for body tissues. The onset of sodic liotironine activity is rapid, taking place within a few hours. Maximum Harmacological response occurs in 2 or 3 days, providing an early clinical response. The biological half-life is about 2- & frac12; days.

T3 is almost totally absorbed, 95% in 4 hours. Hormones contained in natural preparations are absorbed in a similar way to synthetic hormones.

Liothyronina sodium has a rapid interruption of activity, which allows quick dose adjustment and facilitates control of overdose effects if they occur.

The higher affinity of levothyroxine (T4) for both the globulin that connects the thyroid and the prealbumin that connects the thyroid, compared to the triiodothyronin (T3) explains the higher serum levels and the longer half -life of the anterior hormone. Both protein linked hormones exist in the reverse balance with small amounts of free hormone, the latter representing metabolic activity.

Guide to medicines

Information to the patient

Patients treated with thyroid hormones and parents of children with thyroid treatment should be informed that:

Substitution therapy should be taken essentially for life, except in cases of transient hypothyroidism, usually associated with thyroiditis, and those patients receiving a therapeutic study of the drug.

They should immediately report during treatment any signs or symptoms of thyroid hormone toxicity, for example, chest pain, increased pulse rhythm, palpitations, excessive sweating, heat intolerance, nervousness or any other unusual event.

In the concomitant case of diabetes, the daily dose of antidiabetic drugs may require rejusting, as thyroid hormone is replaced. If the thyroid drug is stopped, an insulin dose dose or oral hypoglycemic agent may be required to avoid hypoglycemia. At any time, careful monitoring of glucose urinary levels is mandatory to these patients.

In the case of concomitant oral anticoagulant therapy, prothrombin time should be measured frequently to determine if the dose of oral anticoagulants should be rejected.

Partial hair loss can be experienced by pediatric patients in the first few months of thyroid therapy, but this is usually a transient phenomenon and subsequent recovery is usually the rule.