Jodthyrox^® (Tablets) Instructions for Use

Marketing Authorization Holder

Merck, KGaA (Germany)

ATC Code

H03AA (Thyroid hormones)

Active Substances

Levothyroxine sodium (Rec.INN registered by WHO)

Potassium iodide (Ph.Eur. European Pharmacopoeia)

Dosage Form

Jodthyrox®

Tablets 100 mcg+131 mcg: 50 or 100 pcs.

Dosage Form, Packaging, and Composition

Tablets are almost white, round, flat on both sides, with beveled edges. There is a score on both sides of the tablet, and an engraving “EM 45” on one side of the tablet.

Excipients: microcrystalline cellulose – 81.514 mg, gelatin – 4.5 mg, croscarmellose sodium – 3.5 mg, magnesium stearate – 0.250 mg.

25 pcs. – blisters (2) – cardboard packs.
25 pcs. – blisters (4) – cardboard packs.

Clinical-Pharmacological Group

Thyroid hormone preparation in combination with iodine

Pharmacotherapeutic Group

Thyroid agent

Pharmacological Action

A combined preparation containing the synthetic thyroid hormone levothyroxine and iodine in the form of potassium iodide, which is a structural element in the synthesis of thyroid hormones (thyroxine and triiodothyronine).

The preparation compensates for the deficiency of thyroid hormones. It increases tissue oxygen demand, stimulates their growth and differentiation, and increases the level of basal metabolism (proteins, fats, and carbohydrates). In small doses, it has an anabolic effect, and in large doses, it has a catabolic effect. It inhibits the production of thyroid-stimulating hormone. It enhances energy processes, has a positive effect on the functions of the nervous and cardiovascular systems, liver and kidneys. It compensates for the lack of iodine in the body.

Pharmacokinetics

Pharmacokinetic data are not provided.

Indications

• Hypothyroidism;
• Euthyroid goiter associated with iodine deficiency in children, adolescents and adults, including during pregnancy;
• Prevention of goiter recurrence after thyroid resection.

ICD codes

Dosage Regimen

The daily dose is determined individually depending on the indications. Jodthyrox^® in the daily dose is taken once a day in the morning, on an empty stomach, 30 minutes before breakfast, with the tablet swallowed with a small amount of liquid and without chewing. For infants, the daily dose of Jodthyrox^® is given in one dose 30 minutes before the first feeding. The tablet is dissolved in a small amount of water to a thin suspension immediately before taking the preparation.

The initial dose of the preparation is 1/2 tab./day. After 2-4 weeks of administration, the dose is increased taking into account the patient’s age, body weight and tolerance of the preparation.

The maintenance dose is 1 tab./day. During pregnancy, the maintenance dose is increased to 1-1.5 tab./day.

The duration of administration is set individually and usually ranges from several months to lifelong use.

Adverse Reactions

Allergic reactions in case of hypersensitivity to iodine – increased body temperature, rash, skin hyperemia, itching and burning in the eyes, cough, diarrhea, headache.

Contraindications

• Thyrotoxicosis of any origin;
• Autonomous thyroid adenomas;
• Acute myocardial infarction, acute myocarditis;
• Untreated adrenal cortex insufficiency;
• Dermatitis herpetiformis Duhring;
• Hypersensitivity to iodine.

With caution, the preparation should be prescribed for cardiovascular diseases, including coronary artery disease (atherosclerosis, angina pectoris, history of myocardial infarction), heart failure, arterial hypertension, tachycardia, tachyarrhythmia; for diabetes mellitus, diabetes insipidus, severe long-standing hypothyroidism, adrenal insufficiency, malabsorption syndrome, as well as for elderly patients (dose adjustment may be required).

Use in Pregnancy and Lactation

During pregnancy and lactation, therapy with Jodthyrox^® prescribed for hypothyroidism should be continued.

During lactation, the preparation should be used with caution.

Pediatric Use

The preparation can be used according to indications and in doses taking into account the age of the patients.

Geriatric Use

With caution, the preparation should be prescribed to elderly patients (dose adjustment may be required).

Special Precautions

Before prescribing Jodthyrox^® to patients with heart disease, the cardiovascular disease should be corrected. Jodthyrox^® is started in small doses. If chest pain or other symptoms indicating worsening of the cardiovascular disease develop, the dose of Jodthyrox^® should be reduced.

Elderly patients should be prescribed the preparation in lower doses.

The use of Jodthyrox^® in diabetes mellitus, diabetes insipidus, or adrenal cortex insufficiency may lead to an increase in the severity of these diseases, which may require adjustment of the doses of the preparations used for their treatment.

If allergic reactions occur, Jodthyrox^® should be discontinued.

In hypothyroidism due to pituitary damage, it is necessary to determine whether there is concomitant adrenal cortex insufficiency. In this case, replacement therapy with corticosteroids should be started before initiating treatment of hypothyroidism with thyroid hormones to avoid the development of acute adrenal insufficiency.

Effect on the ability to drive vehicles and operate machinery

Taking Jodthyrox^® in an adequate therapeutic dose does not affect the ability to perform work requiring increased attention and speed of psychomotor reactions.

Overdose

Symptoms of preparation overdose (especially with too rapid dose increase at the beginning of treatment) may include symptoms characteristic of thyrotoxicosis: tachycardia, cardiac arrhythmia, finger tremor, internal restlessness, insomnia, increased sweating, weight loss, diarrhea.

Treatment: withdrawal of the preparation. After the symptoms disappear, treatment is resumed at a lower dose.

Drug Interactions

Levothyroxine enhances the effect of indirect anticoagulants, which may require a reduction in their dose, and also requires monitoring of the blood coagulation index when these preparations are used simultaneously with Jodthyrox^®.

Thyroid hormones may increase the need for insulin and oral hypoglycemic drugs, which requires more frequent monitoring of blood glucose levels during the periods of initiation of treatment with the preparation, as well as when changing its dosing regimen.

Rapid intravenous administration of phenytoin may increase the level of free levothyroxine in the blood plasma, which may cause cardiac arrhythmias.

When used simultaneously with salicylates, dicoumarol, clofibrate, furosemide in high doses, levothyroxine may be displaced from its compounds with plasma proteins.

The use of tricyclic antidepressants with the preparation Jodthyrox^® may lead to an enhancement of their effect.

When used simultaneously, cholestyramine, colestipol and aluminum-containing antacids reduce the plasma concentration of levothyroxine by inhibiting its absorption in the intestine, so the interval between taking Jodthyrox^® and these preparations should be 4-5 hours.

When potassium iodide is used simultaneously with potassium-sparing diuretics, the level of potassium in the blood may increase.

Jodthyrox^® when used simultaneously reduces the effect of cardiac glycosides.

When used simultaneously with anabolic steroids, asparaginase, tamoxifen, pharmacokinetic interaction at the level of protein binding is possible.

When prescribed simultaneously with estrogens or estrogen-containing oral contraceptives, an increase in the dose of Jodthyrox^® may be required.

Somatotropin when used simultaneously with the preparation Jodthyrox^® may accelerate the closure of epiphyseal growth zones.

Taking phenobarbital, carbamazepine and rifampicin may increase the clearance of levothyroxine and require an increase in the dose of the preparation Jodthyrox^®.

Storage Conditions

The preparation should be stored in a dry place, out of the reach of children, at a temperature from 15°C (59°F) to 25°C (77°F).

Shelf Life

Shelf life – 2 years.

Dispensing Status

The preparation is dispensed by prescription.

Important Safety Information

This information is for educational purposes only and does not replace professional medical advice. Always consult your doctor before use. Dosage and side effects may vary. Use only as prescribed.