EUTIROX ® Levothyroxine

EUTIROX ® a drug based on sodium levothyroxine

THERAPEUTIC GROUP: Thyroid preparations

Indications EUTIROX ® Levothyroxine

EUTIROX ® is indicated in all conditions of reduced thyroid function such as goiter, prophylaxis of relapses after surgery, thyroid hypofunction, inflammatory processes, antithyroid therapies to restore normal hormonal balance.

Mechanism of action EUTIROX ® Levothyroxine

The levothyroxine contained in EUTIROX ® constitutes the deficient hormone in the course of hypothyroidism, thus representing a direct replacement therapy.
Taken orally, thanks to the particular structure of the molecule, it is absorbed at the gastrointestinal level for about 42 - 74% of the total dose taken, and bound to plasma proteins such as thyroglobulin, transthyretin and albumin in a minimal part, is distributed to various fabrics.
In these locations, therefore, following deiodination mediated by specific enzymes, the hormone can interact with its specific nuclear receptor by regulating various biological functions such as:

  • Protein synthesis and enzymatic activity, involved in body growth and development;
  • Thermogenesis;
  • Heart rate and contraction;
  • Basal metabolism;
  • Lipolysis induced by catecholamines;
  • Cholesterol metabolism.

It is therefore easy to imagine how the condition of hypothyroidism is characterized by a general slowdown of the body's basal metabolism, myxedema, weight gain, reduction of physical and cognitive abilities, hyperlipidemia, alterations in the menstrual cycle, goiter, cold intolerance and bradycardia.
After a long half-life of several days, the thyroid hormones are partly metabolized in the liver and eliminated with the bile and partly recycled through the entero-hepatic recirculation mechanism.

Studies carried out and clinical efficacy


Endocr J. 2010 Sep 29; 57: 803-9. Epub 2010 Jul 30.

Short term effects of levothyroxine treatment in thyroid multinodular disease.

Cesareo R, Iozzino M, Isgrò MA, Annunziata F, Di Stasio E.

This study evaluates the efficacy of levothyroxine treatment in delaying the clinical evolution of multi-nodular thyroid disease. The preventive effect of this hormone seems justified by the suppression of the endogenous production of TSH, certainly involved in the genesis and development of the disease.


G Chir. 2010 Jun-Jul; 31 (6-7): 303-7.

Hormone replacement therapy after total thyroidectomy. Can the combined treatment be considered effective to get metabolic adequacy? Preliminary results.

Bononi M, De Toma G, Scarpini M, Miccini M, De Cesare A, Meucci M, Amore Bonapasta S, Celotto A, Tocchi A.

The total removal of the thyroid becomes a surgical procedure sometimes indicated in the treatment of some serious pathologies. In patients totally deprived of this important endocrine gland, hormone replacement therapy with T4 has proved effective and well tolerated by patients.


J Clin Endocrinol Metab. 2010 Jul; 95: 3234-41. Epub 2010 May 12.

Thyroid hormone early adjustment in pregnancy (the THERAPY) trial.

Yassa L, Marqusee E, Fawcett R, Alexander EK.

The need for thyroid hormones increases by about 20 - 40% during pregnancy, so in patients with hypothyroidism the dosage of EUTIROX used should be proportionally increased. Although various studies show how adequate therapy can preserve both maternal and fetal metabolic balance, there is currently no standardized therapeutic protocol that can allow the doctor an easy treatment of this condition.

Method of use and dosage

EUTIROX ® tablets containing 25/50/75/100/125/150/175/200 mcg of sodium levothyroxine:
the effective dosage of levothyroxine should be established by the physician on the basis of the patient's physio-pathological conditions, his physical characteristics and the relative clinical picture.
In fact, the various formulations are representative of an important inter-individual variability of the patient's therapeutic needs, and at the same time, allow the doctor to better adapt the therapy itself.
In any case, the therapeutic range for an adult individual fluctuates on average between 50 and 200mcg per day, to be taken with a sip of water in the morning, preferably on an empty stomach.

Warnings EUTIROX ® Levothyroxine

Treatment with levothyroxine-based drugs should be preceded by a "careful evaluation of the patient's clinical conditions, useful for characterizing the real causes of hypothyroidism and treating all other possible etiological aspects incompatible with pharmacological treatment with EUTIROX ®.
During the therapeutic process, the doctor should periodically monitor the TSH levels, to evaluate the efficacy of the therapy and, if necessary, to adjust the dosage, and the liver function, to exclude possible organ fatigue and important changes in the pharmacokinetic properties of the levothyroxine.
The metabolic action of the drug on the bone could facilitate the onset of osteoporosis in patients at risk such as for women in menopause.
EUTIROX ® contains lactose, therefore patients with lactose intolerance, glucose / galactose malabsorption syndrome or lactase enzyme deficiency, may develop gastrointestinal symptoms after taking this medicine.
Headache, dizziness and other neurological symptoms related to taking EUTIROX ® could make the use of machines and driving vehicles dangerous.


Levothyroxine has been shown to be able to cross the placental barrier reaching the fetal circulation. Despite this pharmacokinetic characteristic, the therapeutic doses used in the treatment of hypothyroidism do not seem to cause teratogenic or toxic effects on the fetus, much less induce hyperthyroidism or inhibition of TSH production.
Consequently, the intake of EUTIROX ® during pregnancy could be carried out in case of real need but under strict medical supervision.


Given the central role of levothyroxine in metabolic control, it is easy to imagine how the intake of EUTIROX ® can interfere with numerous functional aspects and with as many active ingredients.
More precisely, levothyroxine could interact with:

  • Hypoglycemic drugs, reducing their therapeutic effect;
  • Coumarin derivatives, enhancing the anticoagulant effect and increasing the risk of bleeding.

On the contrary, the therapeutic effect of EUTIROX ® could be altered by the concomitant intake of cholestyramine, drugs containing aluminum, iron and calcium, salicylates, dicumarol, furosemide, clofibrate, phenytoin, glucoriticoids, beta-sympatholytics, amiodarone and media containing iodine, estrogen , barbiturates, proguanil, antiepileptics and soy-containing compounds (delaying absorption).

Contraindications EUTIROX ® Levothyroxine

EUTIROX ® contraindicated in untreated adrenal insufficiency, untreated pituitary insufficiency, untreated thyrotoxicosis, acute myocardial infarction, acute myocarditis and pancarditis.
EUTIROX ® must not be administered in patients hypersensitive to the active substance or to one of its excipients.

Undesirable Effects - Side Effects

The medical therapy of hypothyroidism with levothyroxine seems well tolerated and without particular side effects, when the dosage used reflects the real needs of the patient.
Side effects of various clinical relevance can instead be observed in case of ill-defined formulations or in the absence of therapeutic need (doping practice or search for the slimming effect).
Adverse reactions clearly fall within the symptomatology of hyperthyroidism with:

  • Cardiovascular disorders: arrhythmias, tachycardia, anginal pain, hypertension, insufficiency and cardiac arrest;
  • Central nervous system disorders: headache, hyperexcitability, insomnia, tremors, emotional lability and epilepsy;
  • Dermatological disorders: hair loss and widespread inflammatory reactions;
  • Endocrine disorders: alterations in the menstrual cycle and adrenal function;
  • Gastro-intestinal disorders and related glands: transaminase alterations, nausea, vomiting, cramps and abdominal pain;
  • Musculoskeletal disorders: osteoporosis, weakness and muscle cramps.


EUTIROX ® sold only under medical prescription.
EUTIROX ® falls within the doping class: Hormones and related substances (prohibited in and out of competition)

The information on EUTIROX ® Levothyroxine published on this page may be out of date or incomplete. For a correct use of this information, see the Disclaimer and useful information page.

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