Tertroxin 20 Μg 20 μg Tablet.

TERTROXIN 20 u03bcg is indicated in the treatment of:

• coma due to myxoedema;
• management of severe chronic thyroid deficiency;
• hypothyroid states arising in treatment of thyrotoxicosis;
• TERTROXIN 20 u03bcg is also used therapeutically in thyrotoxicosis as an adjunct to carbimazole. After six months of this treatment it may be possible to distinguish drug-responsive patients from relapse-prone patients who are better treated with radio-iodine or surgery. Large doses of liothyronine normally suppress the uptake of iodine by the thyroid, but not in thyrotoxicosis and this forms the basis of a routine test for thyrotoxicosis.

Posology

Adults

Thyroid deficiency: Treatment of adults may be started with doses of 10 u03bcg to 20 u03bcg increasing gradually to a total daily dosage of 80 u03bcg to 100 u03bcg after a few days.

Myxoedema coma: 100 u03bcg or more may be administered by stomach tube.

Thyrotoxicosis: As a diagnostic test in adults, 80 u03bcg or more of liothyronine are given daily for seven or eight days. The daily amount should be divided into 3 or 4 doses. Radio-iodine is then administered, and uptake by the thyroid can be estimated about 20 minutes later. Failure to suppress the uptake of radio-iodine is indicative of thyrotoxicosis.

As therapy for thyrotoxicosis with carbimazole: In adults 80 u03bcg of liothyronine daily. In some patients it is possible to discontinue the carbimazole after about a year without subsequent relapse.

Elderly population

The initial dosage should be 5 u03bcg daily (see Method of administration below to obtain small doses). TERTROXIN 20 u03bcg should be given in divided doses two or three times daily.

Paediatric population

The initial dosage should be 5 u03bcg daily (see Method of administration below to obtain small doses). TERTROXIN 20 u03bcg should be given in divided doses two or three times daily.

Method of administration

For oral administration. To obtain small doses: To obtain small doses tablets may be crushed and triturated with lactose for administration as a powder (see Elderly population and Paediatric population above).

TERTROXIN 20 u03bcg is contraindicated in:

• Patients with hypersensitivity to liothyronine sodium or to any excipients in TERTROXIN 20 u03bcg (see section 6.1).
• Patients with angina of effort or cardiovascular disorders.
• Patients with untreated adrenal cortical insufficiency.
• Patients with untreated hyperthyroidism.

Endocrine Disorders

TERTROXIN should be used with caution in patients with concomitant endocrine diseases such as diabetes mellitus or adrenocortical insufficiency.

Myxoedema and myxoedemic coma

In myxoedema, care must be taken to avoid imposing excessive burden on cardiac muscle affected by prolonged severe thyroid depletion. Glucocorticoids should be used in conjunction with thyroid hormones in the management of myxoedemic coma.

Cardiovascular disorders and angina

Angina may be precipitated where there is latent cardiac ischaemia (see section 4.3).

Hypothyroidism

In severe prolonged hypothyroidism, the decreased level of adrenocortical activity may require supplementation with adrenocorticotrophic hormones. Adrenal deficiency must be corrected in patients with hypopituitarism prior to commencement of liothyronine therapy. The use of thyroid hormones has been reported to precipitate a hyperthyroid state.

Obesity

TERTROXIN 20 u03bcg should not be used in the management of obesity in euthyroid patients because doses within the range of daily hormonal requirements are ineffective and larger doses may produce serious or life-threatening adverse effects.

Antidiabetic medicines and anticoagulants

Thyroid treatment may enhance the action of anticoagulants, requiring an initial increased frequency of monitoring of prothrombin times and upset the stability of patients receiving antidiabetic medicines. It is important to remind patients of increased insulin requirements if they are prescribed TERTROXIN 20 u03bcg. Patients should also be reminded of the importance of reporting to the doctor any chest pain, palpitations or excessive sweating.

Laboratory tests

Periodic assessment of thyroid status should be conducted by means of appropriate laboratory tests and clinical observation.

Elderly population

Special care is needed in the elderly who may exhibit increased sensitivity to the effects of thyroid replacement therapy (see section 4.2).

Paediatric population

Infants: Craniosynostosis may occur in infants given high doses of thyroid hormones (see section 4.2).

Children: A partial loss of hair may occur in children (paediatric patients) that are administered with thyroid hormones in the first few months of thyroid therapy, however this effect is usually a transient phenomenon, and later recovery is usually the rule (see section 4.2).

Excipients

TERTROXIN 20 u03bcg contains lactose. Patients with rare hereditary problems of galactose intolerance, total lactase deficiency or glucose-galactose malabsorption should not take TERTROXIN 20 u03bcg.

Anticoagulants

TERTROXIN 20 u03bcg therapy may potentiate the action of anticoagulants by increasing the catabolism of Vitamin K dependent clotting factors.

Anticonvulsant

Initiation or discontinuation of anticonvulsant medicines may alter liothyronine dose requirements. The effect of thyroid preparations, such as TERTROXIN 20 u03bcg, may be enhanced by phenytoin taken concomitantly. Phenytoin levels may be increased by liothyronine. Anticonvulsants such as carbamazepine and phenytoin enhance the metabolism of thyroid hormones and may displace them from plasma proteins.

Aspirin

The effect of thyroid preparations may be enhanced by aspirin. Aspirin displaces thyroid hormones from protein-binding sites.

Ketamine

Ketamine may cause hypertension and tachycardia when administered to patients receiving thyroid replacement therapy.

Oral contraceptives

Co-administration of oral contraceptives may result in an increased dosage requirement of thyroid therapy as estrogens increase levels of thyroid binding globulin.

Cardiac glycosides

If co-administered with cardiac glycosides, adjustment of the dosage of cardiac glycoside may be necessary. Thyroxine may potentiate digitalis toxicity. The increased metabolic rate following liothyronine therapy may increase digitalis requirements.

Colestyramine

Colestyramine given concurrently reduces gastrointestinal absorption of liothyronine as contained in TERTROXIN 20 u03bcg, by binding liothyronine within the gut lumen.

Tricyclic antidepressants

TERTROXIN 20 u03bcg increases receptor sensitivity to catecholamines thus potentially increasing the risk of cardiac dysrhythmias in patients receiving tricyclic antidepressants.

Monitoring patients on liothyronine therapy

A number of medicines may affect thyroid function tests and this should be borne in mind when monitoring patients on liothyronine therapy.

Insulin / oral hypoglycaemics

Patient requirements of insulin or oral hypoglycaemics may increase in patients receiving therapy with liothyronine.

Pregnancy

There is limited placental transfer of thyroid hormones.

Breastfeeding

Liothyronine, as contained in TERTROXIN 20 u03bcg, is excreted in breast milk.

Fertility

No data available.

Since adverse reactions such as headaches have been reported in patients receiving TERTROXIN 20 u03bcg, patients should not drive, use machinery or perform any tasks that require concentration, until they are certain that TERTROXIN 20 u03bcg does not adversely affect their ability to do so (see section 4.4 and/or 4.8).

a) Summary of the safety profile

At the beginning of treatment, ordinary therapeutic doses may cause anginal pain, palpitations and cramps in the skeletal muscle.

b) Tabulated list of adverse reactions

System organ class Less Frequent

• Endocrine disorders Myxoedema 2
• Metabolism and nutrition disorders Excessive loss of weight 1
• Psychiatric disorders Restlessness 1 , excitability 1
• Nervous system disorders Headache 1
• Cardiac disorders Cardiac dysrhythmias 1 , tachycardia 1
• Vascular disorders Flushing 1
• Gastrointestinal disorders Diarrhoea 1
• Skin and subcutaneous tissue disorders Sweating 1
• Musculoskeletal and connective tissue disorders Muscle weakness 1

c) Description of selected adverse reactions

1 TERTROXIN 20 u03bcg is capable of producing the same side effects and can show the same symptoms of overdosage as the thyroid hormone, but in practice (except in myxoedema) these symptoms are uncommon and they disappear rapidly when treatment is stopped or the dosage is reduced, also refer to section 4.9. Overdose.

2 The euthyroid patient shows much greater tolerance to the thyroid hormone than the thyroprivic case. It has already been mentioned that in myxoedema side effects from the rapid re-establishment of the normal state may occur; these too are quickly controlled by reducing the dosage.

Reporting of suspected adverse reactions

If you get side effects, talk to your doctor, pharmacist or nurse. You can also report side effects to SAHPRA: via the u201c6.04 Adverse Drug Reactions Reporting Formu201d, found online under SAHPRAu2019s publications: https://www.sahpra.org.za/Publications/Index/8 Aspen Pharmacare: E-mail: [email protected] Tel: 0800 118 088 / +27 (0)11 239-6200

Symptoms

The following effects are indicative of excessive dosage, and usually disappear on reduction of dosage or withdrawal of treatment for a day or two. Anginal pain, cardiac dysrhythmias, palpitation, and cramps in skeletal muscle; also, tachycardia, diarrhoea, restlessness, irritability, nervousness excitability, headache, flushing, sweating, excessive loss of weight and muscular weakness. Congestive heart failure may be induced or aggravated.

Treatment

Dosage should be reduced or therapy temporarily discontinued if signs and symptoms of overdose appear. Treatment may be reinstated at a lower dosage. In normal individuals, normal hypothalamic-pituitary-thyroid axis function is restored in 6 to 8 weeks after thyroid suppression. Treatment of acute massive thyroid hormone overdosage, is aimed at reducing gastrointestinal absorption of the medicines and counteracting central and peripheral effects, mainly those of increased sympathetic activity. Vomiting may be induced initially, if further gastrointestinal absorption can be reasonably prevented and barring contraindications such as coma, convulsions, or loss of the gagging reflex. Treatment is symptomatic and supportive. Oxygen may be administered, and ventilation maintained. Measures to control fever, hypoglycemia, or fluid loss, should be instituted if needed. The patient may present in shock. Symptoms may resemble thyroid storm and treatment is symptomatic. Congestive heart failure may require appropriate treatment. Supportive measures may include measures such as the management of fever, hypoglycaemia or fluid loss if necessary, as per the above.