Levothyroxine, at doses individualized according to patient response, is effective as replacement or supplemental therapy in hypothyroidism of any etiology, except transient hypothyroidism during the recovery phase of subacute thyroiditis. Levothyroxine is also effective in the suppression of pituitary TSH secretion in the treatment or prevention of various types of euthyroid goiters, including thyroid nodules.Pituitary TSH Suppression In the treatment or prevention of various types of euthyroid goiters (see WARNINGS and PRECAUTIONS including thyroid nodules (see WARNINGS and PRECAUTIONS subacute or chronic lymphocytic thyroiditis (Hashimotos thyroiditis multinodular goiter (see WARNINGS and PRECAUTIONS ) and, as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well differentiated.
If you are taking any of these drugs, separate them from this medication by at least 4 hours. Symptoms of low thyroid hormone levels include tiredness, muscle aches, constipation, dry skin, weight gain, slow heartbeat, or sensitivity to cold.O, molecular weight of 798.86 g/mol (anhydrous and structural formula as shown: Inactive Ingredients Levothyroxine sodium tablets, USP, for oral administration, are available containing 25 mcg, 50 mcg, 75 mcg, 88 mcg, 100 mcg, 112 mcg, 125 mcg, 137 mcg, 150 mcg, 175 mcg, 200 mcg or 300 mcg of Levothyroxine sodium, USP.
This monograph includes information on the following: 1) Levothyroxine 2) Liothyronine 3) Liotrix 4) Thyroglobulin 5) Thyroid VA CLASSIFICATION Levothyroxine Primary: HS851 Secondary: AN500; DX900. Liothyronine Primary: HS851 Secondary: AN500; DX900.However, caution is necessary in interpreting results of thyroid function tests in neonates, because serum T 4 concentrations are transiently elevated and serum T 3 concentrations are transiently low, and the infant pituitary is relatively insensitive to the negative feedback effect of thyroid hormones.
A feedback system involving the hypothalamus, anterior pituitary, and thyroid normally regulates circulating thyroid hormone concentrations. Absorption: Oral: Levothyroxine: Incomplete and variable, especially when taken with food; average 50 to 75 13.Thyrotropin-releasing hormone (TRH) released from the hypothalamus stimulates secretion of thyrotropin-stimulating hormone, TSH, from the anterior pituitary. TSH, in turn, is the physiologic stimulus for the synthesis and secretion of thyroid hormones, L-thyroxine (T 4 ) and L-triiodothyronine (T 3 by the thyroid gland.
Liothyronine is recommended by some clinicians because of its short half-life and readily reversible effects for initial therapy in myxedema and myxedema coma, as well as for hypothyroid patients who also have heart disease, although there are significant risks associated with the latter use.Carcinoma, thyroid (prophylaxis and treatment) 1 Thyroid hormones are indicated in the treatment of thyrotropin-dependent thyroid gland carcinoma 13. Some clinicians believe that prophylactic administration of thyroid hormones after neck irradiation will prevent development of thyroid gland carcinoma.
Use this medication regularly in order to get the most benefit from it. To help you remember, take it at the same time each day. Do not stop taking this medication without first consulting with your doctor.Liothyronine may also be preferred during preparation for radioisotope scanning procedures or when gastrointestinal absorption processes are impaired. Disadvantages of thyroid extract and thyroglobulin tablets are their variable potencies and the fact that triiodothyronine (T 3) and thyroxine (T 4) concentrations fluctuate and cannot be used to regulate dosage.
Carcinogenicity/Mutagenicity Studies have not been done in animals. A reported association with breast cancer has not been confirmed and does not justify withholding thyroid hormone treatment. Pregnancy/Reproduction Pregnancy Thyroid hormones cross the placenta, but only to a limited extent.2 Aluminum Lake 175. D C Red No. 27 Aluminum Lake, D C Red No. 30 Aluminum Lake, FD C Blue No. 1 Aluminum Lake 200 FD C Red No. 40 Aluminum Lake 300 D C Yellow No.
Thyroid function studiesLevothyroxine 1 and liothyronine are indicated as diagnostic aids (for example, the T 3 suppression test although this use has generally been replaced by other tests 08 13. Unaccepted Use of thyroid hormones to treat vague symptoms such as dry skin, fatigue, constipation, abnormalities of reproductive function, growth retardation, or obesity without laboratory.Biotransformation: As for endogenous thyroid hormone; levothyroxine (approximately 30 09 ) is deiodinated in peripheral tissues; small amounts are metabolized in the liver and excreted in bile. Half-life: Levothyroxine: Euthyroid: 6 to 7 days.
Minimal amounts of exogenous thyroid hormones are distributed into breast milk. Pediatrics Studies performed to date have not demonstrated pediatrics-specific problems that would limit the usefulness of thyroid hormones in children.Table 1: Pharmacokinetic Parameters of Thyroid Hormones in Euthyroid Patients Hormone Ratio in Thyroglobulin Biologic Potency t (days) Protein Binding Levothyroxine (T 4 ) Liothyronine (T 3 ) 10 to to 7 2 99.96 99.5 Indications and Usage for Levothyroxine Levothyroxine sodium is used for the following indications: Hypothyroidism As replacement or supplemental therapy in.
Protein-bound thyroid hormones exist in reverse equilibrium with small amounts of free hormone. Only unbound hormone is metabolically active. Many drugs and physiologic conditions affect the binding of thyroid hormones to serum proteins (see PRECAUTIONS : Drug Interactions and Drug-Laboratory Test Interactions ).In euthyroid patients, doses within the range of daily hormonal requirements are ineffective for weight reduction. Larger doses may produce serious or even life threatening manifestations of toxicity, particularly when given in association with sympathomimetic amines such as those used for their anorectic effects.
Time to peak therapeutic effect With chronic stable oral dosing: Levothyroxine, thyroglobulin, thyroid: 3 to 4 weeks. Liothyronine: 48 to 72 hours 01. Duration of therapeutic action After withdrawal of chronic therapy: Levothyroxine, thyroglobulin, thyroid: 1 to 3 weeks.Contraindications Levothyroxine sodium tablets are contraindicated in patients with untreated subclinical (suppressed serum TSH level with normal T 3 and T 4 levels) or overt thyrotoxicosis of any etiology and in patients with acute myocardial infarction.
Liothyronine: 25 mcg (0.025 mg). Liotrix Levothyroxine and liothyronine: 60 mcg (0.06 mg) and 15 mcg (0.015 mg or 50 mcg (0.05 mg) and 12.5 mcg (0.0125 mg respectively. Thyroglobulin: 60 mg.Distribution Circulating thyroid hormones are greater than 99 bound to plasma proteins, including thyroxine-binding globulin (TBG thyroxine-binding prealbumin (TBPA and albumin (TBA whose capacities and affinities vary for each hormone. The higher affinity of both TBG and TBPA for T 4 partially explains the higher serum levels, slower metabolic clearance, and longer half-life of T.
Thyroid replacement treatment is usually taken for life. There are different brands of levothyroxine available. Do not change brands without first consulting your doctor or pharmacist. Certain medications (such as cholestyramine, colestipol, colesevelam, antacids, sucralfate, simethicone, iron, sodium polystyrene sulfonate, calcium supplements, orlistat, sevelamer, among others) can decrease the amount of thyroid hormone that is.Liothyronine: Up to 72 hours. Precautions to Consider Note: The following precautions apply to patients with abnormal thyroid status (hypothyroidism or, in some cases, hyperthyroidism). Patients in stable euthyroid condition as a result of continuing thyroid hormone therapy may be expected to respond in the same way as individuals with normal thyroid function and, therefore.
A portion of the conjugated hormone reaches the colon unchanged and is eliminated in the feces. Approximately 20 of T 4 is eliminated in the stool. Urinary excretion of T 4 decreases with age.30 Aluminum Lake 125 FD C Blue No. 1 Aluminum Lake, FD C Red No. 40 Aluminum Lake, FD C Yellow No. 6 Aluminum Lake 137 FD C Blue No. 2 Aluminum Lake 150 FD C Blue No.
Take this medication with a full glass of water unless your doctor directs you otherwise. If you are taking the capsule form of this medication, swallow it whole. Do not split, crush, or chew.Liotrix is no longer considered advantageous because of the natural conversion of T 4 to T 3 in the tissues. Goiter (prophylaxis 1 and treatment)Thyroid hormones are indicated to suppress the growth of some 05 adenomatous goiters, and to prevent the goitrogenic effects of other medications such as lithium, aminosalicylic acid, and some sulfonamide compounds.
Specific indications include: primary (thyroidal secondary (pituitary and tertiary (hypothalamic) hypothyroidism and subclinical hypothyroidism. Primary hypothyroidism may result from functional deficiency, primary atrophy, partial or total congenital absence of the thyroid gland, or from the effects of surgery, radiation, or drugs, with or without the presence of goiter.Intra-amniotic levothyroxine has been used to treat fetal hypothyroidism. FDA Pregnancy Category A. Breast-feeding Problems in humans have not been documented with appropriate use of thyroid hormones in women who are breast-feeding.
Levothyroxine is contraindicated in patients with uncorrected adrenal insufficiency since thyroid hormones may precipitate an acute adrenal crisis by increasing the metabolic clearance of glucocorticoids (see PRECAUTIONS ). Levothyroxine sodium is contraindicated in patients with hypersensitivity to any of the inactive ingredients in Levothyroxine sodium tablets.Thyroid hormones do not readily cross the placental barrier (see PRECAUTIONS : Pregnancy ). Metabolism T 4 is slowly eliminated (see Table 1). The major pathway of thyroid hormone metabolism is through sequential deiodination.
Do not prepare a supply in advance or mix the tablet in soy infant formula. Consult your pharmacist for more information. Dosage is based on your age, weight, medical condition, laboratory test results, and response to treatment.In most cases, relative need for thyroid hormone dosage adjustment will depend on the thyroid state of the patient and the dosages of all medications involved. Dosage adjustment should be based on results of thyroid function tests and clinical status 03.
Circulating serum T 3 and T 4 levels exert a feedback effect on both TRH and TSH secretion. When serum T 3 and T 4 levels increase, TRH and TSH secretion decrease.Thyroid USP: 60 mg. Note: Because of the difficulty in measuring actual hormonal content of thyroglobulin and Thyroid USP, the measurable amounts of levothyroxine and liothyronine in these preparations may be less than the clinical equivalent.