Generic Synthroid (levothyroxine) is a thyroid medicine that replaces a hormone normally produced by your thyroid gland. It is used when your thyroid does not produce enough of this hormone on its own.
What is this medicine?
Generic Synthroid is a medication that is used to treat hypothyroidism, euthyroid goiter, thyroid cancer (after surgical treatment), diffuse toxic goiter. It is used as replacement therapy and for the prevention of goiter recurrence after thyroid resection. It is also used as a diagnostic tool during the thyroid suppression test.
Who should not take Synthroid?
Do not take this drug if you have hypersensitivity, untreated thyrotoxicosis, acute myocardial infarction, acute myocarditis, untreated adrenal cortex insufficiency (must be compensated before starting therapy).
Restrictions of use: IHD (atherosclerosis, angina pectoris, a history of myocardial infarction), arterial hypertension, arrhythmia, diabetes mellitus and diabetes insipidus, severe long-term hypothyroidism, malabsorption syndrome (dose adjustment may be required), pituitary insufficiency, old age.
How to use Synthroid for best results?
The drug is taken orally, in the morning, on an empty stomach, half an hour before breakfast. It is washed down with a small amount of liquid (for example, half a glass of liquid).
The daily dose can be taken in a single dose.
Children receive the entire dose immediately, at least 30 minutes before the first meal.
If you missed one dose, you should not increase the dose next time.
An individual daily dose should be determined based on the results of laboratory tests and clinical studies.
Thyroid hormone therapy should be started at a low dose and gradually increased every 2–4 weeks until a full replacement dose is reached.
Newborns and children with congenital hypothyroidism, for whom rapid replacement therapy is important usually take 10 to 15 mcg per kg of body weight once a day for 3 months. Then, the dose should be individually adjusted depending on clinical data, thyroid hormones and TSH values.
In elderly patients with coronary heart disease, as well as in patients with severe or long-term hypothyroidism, special caution is required when initiating therapy with thyroid hormones, that is, it is recommended to start therapy with a low dose (for example, 12.5 mcg/day), which should slowly increase.
Experience has shown that low doses are sufficient for patients with low body weight and for patients with large nodular goiter.
With euthyroid goiter, the duration of treatment is 6 months to 2 years, as necessary. If the treatment is not effective during this time, surgery or radioactive iodine therapy should be considered.
What may interact with this drug?
Synthroid reduces the effect of insulin and oral antidiabetic drugs, cardiac glycosides, enhances indirect anticoagulants, tricyclic antidepressants.
Colestyramine, colestipol, aluminum hydroxide reduce plasma concentration due to inhibition of absorption in the intestine.
Phenobarbital and phenytoin accelerate metabolic clearance without increasing the proportion of free T3 and T4 in the blood.
Estrogens increase the concentration of the fraction associated with thyroglobulin (effectiveness decreases).
Anabolic steroids, asparaginase, clofibrate, furosemide, salicylates, tamoxifen alter protein binding.
Amiodarone, aminoglutethimide, aminosalicylic acid, ethionamide, antithyroid drugs, beta-blockers, carbamazepine, chloral hydrate, diazepam, levodopa, dopamine, metoclopramide, lovastatin, somatostatin and others can change the levels of thyroid hormones.
What should I watch for while taking this drug?
The drug is not indicated for use in children under the age of 6 years.
Caution should be exercised when prescribing the drug to elderly patients, patients with angina pectoris, hypertension, epilepsy, adrenal insufficiency and pituitary insufficiency, and diabetes mellitus.
If there are signs of hyperthyroidism during treatment with Generic Synthroid, it is recommended to reduce the daily dose or interrupt therapy for several days. When side effects disappear, treatment can be gradually resumed. In children, the administration of levothyroxine in a high initial dose can lead to impaired renal function. Children with epilepsy may experience an increase in the frequency of seizures.
During pregnancy and lactation, levothyroxine therapy is continued under medical supervision. The drug is well studied, therefore there is no reason to assume that it has embryotoxic and teratogenic properties.
An overdose of Synthroid is accompanied by symptoms of hyperthyroidism (weight loss, palpitations, sinus tachycardia, arrhythmia, angina pectoris, heart failure, tremor, headache, insomnia, heat intolerance, fever, irritability, diarrhea, abdominal pain); increased levels of T3 and T4 in blood plasma and free thyroxine index. Depending on the severity of symptoms, it is recommended to reduce the dose or temporarily discontinue levothyroxine. With severe clinical symptoms, treatment includes stomach washing, administration of colestyramine, β-adrenergic blockers, oxygen therapy. Thyrostatic agents are not used. In acute poisoning (suicidal attempt), plasmapheresis can help.
It is recommended to periodically determine the concentration of thyroid-stimulating hormone (TSH) in the blood, an increase in which indicates a dose deficiency.
The drug does not affect the activities associated with driving vehicles and operating machinery.
What are the side effects of taking Generic Synthroid?
In some cases, the drug can cause tachycardia, heart rhythm disturbance, chest pain, tremor, anxiety, insomnia, hyperhidrosis, weight loss, diarrhea, alopecia, impaired adrenal function (with pituitary or hypothalamic hypothyroidism), impaired renal function in children, allergic reactions (skin rash, itching skin).
How to store this medicine?
Store the drug away from light and moisture. Store the drug at 25°C (77°F). The tablets should be protected from heat, light and moisture.