Pharmacological action Levothyroxine sodium 50 mcg
Levothyroxine The preparation of thyroid hormones. Synthetic levo isomer of thyroxine. In small doses, has an anabolic effect. In medium doses, stimulates the growth and development, increases in oxygen demand of tissues, stimulates the metabolism of proteins, fats and carbohydrates, stimulates the cardiovascular system and central nervous system. In high doses, inhibits the production of TSH and hypothalamic TTRG pituitary.
Pharmacokinetics Levothyroxine sodium 50 mcg
After oral administration, absorbed from the gastrointestinal tract, absorption is 48-79%. Receiving fasting increases the absorption of the active substance. Cmax in plasma is reached after about 6 h. The binding to plasma proteins (thyroxine-binding globulin, thyroxine-binding prealbumin and albumin) – more than 99%. Vd is 0.5 L / kg. Distribution is mainly in the liver, brain and muscles.
In various tissues is monodeyodirovanie approximately 80% of levothyroxine sodium to form triiodothyronine (T3) and inactive products. A small amount of active substance undergoes deamination and decarboxylation to form tetrayodtirouksusnoy acid and conjugation with glucuronic and sulfuric acids (the liver).
T1 / 2 at 6-7 days. About 15% is excreted by the kidneys and bile in unchanged form and as conjugates.
Statement Levothyroxine sodium 50 mcg
Primary and secondary hypothyroidism, goiter mixed, comprehensive treatment of toxic goiter and autoimmune thyroiditis, euthyroid hyperplasia of the thyroid gland, prevention of recurrence after surgical treatment of nodular and malignant tumors of the thyroid gland, cretinism.
Differential-diagnostic test for thyroid suppression.
Dosage regimen Levothyroxine sodium 50 mcg
Set individually depending on the evidence. Apply a dose of 12.5-200 mg 1 time / day for 20-30 minutes before eating.
In carrying out differential diagnosis of thyroid suppression test – single dose of 3 mg or 2 weeks at 200 mg 1 time / day.
Side effect Levothyroxine sodium 50 mcg
Symptoms of hyperthyroidism: possible (when used in high doses, including at the dose is increased too quickly at the beginning of treatment), tachycardia, palpitations, arrhythmias, angina, headache, nervousness, tremors, sleep disturbances, feeling of inner restlessness, muscle weakness and cramps, weight loss, diarrhea, menstrual disorders, vomiting.
Contraindications Levothyroxine sodium 50 mcg
Hyperthyroidism of different genesis, acute myocardial infarction, untreated adrenal insufficiency, hypersensitivity to levothyroxine sodium.
Pregnancy and breastfeeding Levothyroxine sodium 50 mcg
During pregnancy and lactation levothyroxine sodium should be used under medical supervision. Used in combination with tireostaticheskim agents in pregnancy is contraindicated due to the increased risk of hypothyroidism in the fetus.
Cautions Levothyroxine sodium 50 mcg
With great caution in patients with cardiovascular disease (including coronary artery disease, heart failure, hypertension). In these cases, levothyroxine sodium should be used in a low initial dose, increasing it slowly and at long intervals.
Elderly patients and with prolonged duration of hypothyroidism treatment should be started gradually.
When thyroid replacement therapy in patients with adrenal insufficiency without adequate maintenance therapy with corticosteroids, may develop acute adrenal crisis.
Be wary of diabetes and diabetes insipidus.
In carrying out differential diagnosis of thyroid suppression test in patients with diabetes need to increase doses of antidiabetic agents.
In some cases, thyroid hormone can cause or exacerbate pre myasthenic syndrome.
Drug Interactions Levothyroxine sodium 50 mcg
Levothyroxine sodium potentiates the effects of indirect anticoagulants (coumarin), reduces the effectiveness of oral hypoglycemic agents.
In patients with hypothyroidism and concomitant diabetes mellitus at the start of substitution therapy with thyroid hormones may increase the need for insulin or oral hypoglycemic agents.
Salicylates, bishydroxycoumarin, furosemide (250 mg), clofibrate may displace levothyroxine from its association with plasma proteins.
Sucralfate, aluminum hydroxide, calcium carbonate reduces the absorption of levothyroxine from the gastrointestinal tract.
Kolestiramin reduces absorption of levothyroxine sodium from the gastrointestinal tract.
In the application of ritonavir may increase the need for levothyroxine.
In the application of sertraline in patients with hypothyroidism may decrease the effects of levothyroxine sodium.
With the rapid i / v administration of phenytoin in patients receiving levothyroxine sodium may increase the level of free levothyroxine in blood plasma, and the arrhythmia may occur.
With the simultaneous use of chloroquine may increase the metabolism of levothyroxine, apparently due to induction of liver enzymes with chloroquine. Patients receiving levothyroxine sodium, the application of proguanil or chloroquine may increase the concentration of TSH.
