LEVOTHYROXINE ZYDUS

Posology:

The treatment of any thyroid disorder should be determined on an individual basis, taking account of clinical response, biochemical tests and regular monitoring. The individual daily dose should be determined on the basis of laboratory tests and clinical examinations.

As a number of patients show elevated concentrations of T4 and fT4, basal serum concentration of thyroid-stimulating hormone provides a more reliable basis for following treatment course. Patients switching from the oral solution to the tablet form or from the tablet form to the oral solution should be monitored closely.

Levothyroxine is best taken as a single dose on an empty stomach, usually before breakfast. Hypothyroidism (congenital or acquired) Adults, children over 12 years Initial dose: 50 - 100 microgram daily before breakfast. Usual maintenance dose 100 - 200 microgram daily.

The initial dose is adjusted by 25 to 50 microgram increments at 3 – 4 week intervals until clinical response and measurements of plasma thyroxine and thyroid stimulating hormone indicate that the thyroid deficiency is corrected and a maintenance dose established.

Diffuse non toxic goitre or goitre associated with Hashimoto's thyroiditis The recommended dose is 50-200 μg/day. Suppression therapy in thyroid carcinoma The recommended dose is 150-300 μg/day. g. 5 microgram/day fortnightly) with frequent monitoring of thyroid hormones.

A dosage, lower than optimal dosage giving complete replacement therapy, consequentially not resulting in a complete correction of TSH level, might therefore need to be considered. Paediatric population The maintenance dose is generally 100 to 150 microgram per m² body surface area.

For neonates and infants with congenital hypothyroidism, where rapid replacement is important, the initial recommended dosage is 10 to 15 microgram per kg BW per day for the first 3 months. Thereafter, the dose should be adjusted individually according to the clinical findings and thyroid hormone and TSH values.

5-50 microgram per day. The dose should be increased gradually every 2 to 4 weeks according to the clinical findings and thyroid hormone and TSH values until the full replacement dose is reached. Infants should be given the total daily dose at least half an hour before the first meal of the day.

The following side effects are usually due to excessive dosage, and correspond to symptoms of hyperthyroidism. Adverse reactions listed below have been observed during clinical studies and/or during marketed use and are based on clinical trial data and classified according to MedDRA System Organ Class.

These reactions usually disappear after dose reduction or withdrawal of treatment.

Frequency categories are defined according to the following convention:

Not known (cannot be estimated from the available data) System organ class Frequency Undesirable effects Immune system disorders Not known Hypersensitivity reaction Endocrine disorders Not known Thyrotoxic crisis1 Psychiatric disorders Not known Restlessness, agitation, Insomnia Nervous system disorders Not known Tremor, headache Cardiac disorders Not known Angina pectoris, arrhythmia, palpitations, tachycardia Vascular disorders Not known Flushing Respiratory, thoracic and mediastinal disorders Not known Dyspnoea Gastrointestinal disorders Not known Diarrhoea, vomiting Skin and subcutaneous tissue disorders Not known Hyperhidrosis, alopecia, rash, pruritus Musculoskeletal and connective tissue disorder Not known Arthralgia, muscle spasm, muscular weakness Reproductive system disorders Not known Menstruation irregular General disorders and administration site conditions Not known Pyrexia, malaise, oedema Investigations Not known Weight decreased 1 Thyroid crisis have occasionally been reported following massive or chronic intoxication and cardiac arrhythmias, heart failure, coma and death have occurred.

Paediatric population Heat intolerance, transient hair loss, benign intracranial hypertension, craniostenosis in infants and premature closure of epiphysis in children. Reporting of suspected adverse reactions If you get any side effects, talk to your doctor or pharmacist.

Thyroid treatments should be used with caution in patients with cardiovascular disorders, including myocardial insufficiency and hypertension. To minimise the risk of adverse effects of undetected overtreatment, such as atrial fibrillation and fractures associated with low serum levels of thyroid stimulating hormone (TSH) in older patients, it is important to monitor serum TSH and adjust the dose accordingly during long term use Thyroid replacement therapy should be introduced gradually in elderly patients, and those with severe long standing hypothyroidism.

Special care is needed when there are symptoms of myocardial insufficiency or ECG evidence of myocardial infarction and for similar reasons the treatment of hypothyroidism in the elderly should be initiated cautiously. Patients with adrenal insufficiency may react unfavourably to levothyroxine treatment so it is advisable to initiate corticosteroid therapy before giving levothyroxine.

Caution should also be exercised when administering levothyroxine to diabetics or patients on glycosides. Sub-clinical hyperthyroidism may be associated with bone loss. To minimise the risk of osteoporosis, dosage of levothyroxine sodium should be titrated to the lowest possible effective level.

Parents of children receiving a thyroid agent should be advised that partial loss of hair may occur during the first few months of therapy, but this effect is usually transient and subsequent re-growth usually occurs. Even slight drug-induced hyperthyroidism must be avoided in patients with coronary failure, cardiac insufficiency or tachycardiac arrhythmias.

Hence frequent checks of thyroid hormone parameters must be made in these cases. In the case of secondary hypothyroidism the cause must be determined before replacement therapy is given and if necessary replacement treatment of a compensated adrenal insufficiency must be commenced.

Where thyroid autonomy is suspected a TRH test should be carried out or a suppression scintigram obtained before treatment. Levothyroxine should not be given in hyperthyreotic states other than as concomitant supplementation during anti-thyroid drug treatment of hyperthyroidism.

1. - In patients with adrenal insufficiency without adequate corticosteroid cover. - Treatment with Levothyroxine Oral Solution must not be initiated in acute myocardial infarction, acute myocarditis, and acute pancarditis. 6).