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LEVOTHYROXINE is a brand name for Levothyroxine (also known as Thyroxine). The medicine, its uses, side effects and dosage are the same regardless of brand.
Used for: Recommended clinical indications: Control of hypothyroidism, congenital hypothyroidism in infants, acquired hypothyroidism in children and juvenile myxoedema.
Verbatim from this product's MHRA label. Tap a section to expand.
Posology In younger patients, and in the absence of heart disease, a serum Levothyroxine (T4) level of 70 to 160 nanomols per litre, or a serum thyrotrophin level of less than 5 milli-units per litre should be targeted. A pre-therapy ECG is valuable because ECG changes due to hypothyroidism may be confused with ECG evidence of cardiac ischaemia.
If too rapid an increase in metabolism is produced (causing diarrhoea, nervousness, rapid pulse, insomnia, tremors, and sometimes anginal pain where there is latent cardiac ischaemia,) dosage must be reduced, or withheld, for a day or two, and then re-started at a lower dose level.
Adults Patients under 50 years of age:
Initially 50 to 100 micrograms daily, preferably taken on an empty stomach, at least 30 minutes and preferably 1 hour before food, ideally taken before breakfast or your first meal of the day. Adjust at three to four week intervals by 50 micrograms until normal metabolism is steadily maintained.
The final daily dose may be up to 100 to 200 micrograms. The dose may need to be increased during pregnancy.
Patients aged over 50 years:
For patients over 50 years, initially, it is not advisable to exceed 50 micrograms daily. In this condition, the daily dose may be increased by 50 micrograms at intervals of every 3-4 weeks, until stable thyroxine levels are attained.
The final daily dose may be up to 50 to 200 micrograms.
Patients over 50 years with cardiac disease:
Where there is cardiac disease, 25 micrograms daily or 50 micrograms on alternate days is more suitable. In this condition, the daily dose may be increased by 25 microgram increments at intervals of every 4 weeks, until stable thyroxine levels are attained.
The final daily dose may be up to 50 to 200 micrograms. For patients aged over 50 years, with or without cardiac disease, clinical response is probably a more acceptable criteria of dosage rather than serum levels. Elderly Same as that for patients aged over 50 years.
Paediatric population The maintenance dose is generally 100 to 150 micrograms per m² body surface area. The dose for children depends on their age, weight and the condition being treated. Regular monitoring is required to make sure he/she gets the right dose.
Side-effects are usually indicative of excessive dosage and usually disappear on reduction of dosage or withdrawal of treatment for a few days. 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.
Frequency categories are defined according to the following convention:
Not known (cannot be estimated from the available data) System organ class Undesirable effects Immune system disorders hypersensitivity reactions, allergic reactions of the skin and respiratory tract may occur Metabolism and Nutrition disorders increased appetite Psychiatric disorders agitation, restlessness, insomnia Nervous system disorders tremor, headache, idiopathic intracranial hypertension in children Cardiac disorders angina pectoris, arrhythmia, palpitations, tachycardia, myocardial infarction, cardiac failure Vascular disorders flushing, hypertension, cases of circulatory collapse in very low birth weight preterm neonates (see section “Special warnings and precautions for use”).
Respiratory, thoracic and mediastinal disorders dyspnoea Gastrointestinal disorders diarrhoea, vomiting, abdominal pain, nausea Skin and subcutaneous tissue disorders angiodema, rash, urticaria, pruritus, hyperhidrosis, alopecia, transient alopecia in children Musculoskeletal and Connective tissue disorders arthralgia, muscle spasms, muscular weakness, craniosynostosis in infants, epiphyses premature fusion Reproductive system and breast disorders menstruation irregular General disorders and administration site conditions headache, pyrexia, malaise, oedema, temperature intolerance Investigations weight decreased Paediatric population Heat intolerance, transient hair loss, benign intracranial hypertension, craniostenosis in infants and premature closure of epiphysis in children.
2) and those with long standing hypothyroidism to avoid any sudden increase in metabolic demands. Patients with panhypopituitarism or other causes predisposing to adrenal insufficiency may react to levothyroxine treatment, and it is advisable to start corticosteroid therapy before giving levothyroxine to such patients.
Levothyroxine sodium should be used with caution in patients with cardiovascular disorders including angina pectoris, arteriosclerosis, coronary artery disease, hypertension, symptoms or ECG evidence of myocardial infarction and in older people who have a greater likelihood of occult cardiac disorders.
A patient with prolonged myxoedema should be restored to normality only gradually. 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.
In individuals suspected to have cardiovascular disease or to be at high risk, it is important to perform an ECG prior to commencement of levothyroxine treatment in order to detect changes consistent with ischaemia in which case, levothyroxine should be initiated at a low dose, followed by cautious dose escalation to avoid worsening of ischaemia or precipitation of an infarct.
Special care is needed for the elderly and for patients with symptoms of myocardial insufficiency, or ECG evidence of myocardial infarction. Thyroid replacement therapy may cause an increase in dosage requirements of insulin or other anti-diabetic therapy (such as metformin).
Care is needed for patients with diabetes mellitus, and diabetes insipidus. See note above regarding withdrawal of treatment. Subclinical 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.
1 In addition Levothyroxine is contra-indicated in: • Thyrotoxicosis • adrenal gland disorder or untreated adrenal insufficiency • combination therapy of hyperthyroidism with levothyroxine and anti-thyroid agents is not indicated in pregnancy.
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Not medical advice. Always read the patient information leaflet and follow your prescriber or pharmacist.
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Infants should be given the total daily dose at least half an hour before the first meal of the day.
Congenital hypothyroidism in infants:
For neonates and infants with congenital hypothyroidism, where rapid replacement is important, the initial recommended dosage is 10 to 15 micrograms 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 micrograms 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.
Juvenile myxoedema in children:
The initial recommended dosage is 25 micrograms daily. In such conditions, the daily dose may be increased by 25 micrograms at intervals of every 2 - 4 weeks, until mild symptoms of hyperthyroidism are seen. The dose will then be reduced slightly.
Method of administration For oral administration. In children under 5 years of age, the administration of whole tablets is not recommended. It is also not recommended that levothyroxine tablets are crushed and dispersed in water or other liquids, owing to limited solubility which could lead to dosing inaccuracy.
In this age group it is preferable to administer an approved oral solution of levothyroxine.
Symptoms may not appear until several days after the administration of levothyroxine. All these reactions usually disappear on reduction of the dosage or temporary withdrawal of treatment. Cardiac disease may be exacerbated by the administration of thyroid hormones resulting in severe angina pectoris, myocardial infarction or sudden cardiac death.
Gross over dosage has been reported to result in a clinical state resembling thyroid storm, and in collapse and coma. Some patients may experience a severe reaction to high levels of thyroid hormone. This is called a “thyroid crisis” with any of the following symptoms: • Hyperpyrexia, tachycardia, arrhythmia, hypotension, cardiac failure, jaundice, confusion, seizure and coma Reporting of suspected adverse reactions: Reporting suspected adverse reactions after authorisation of the medicinal product is important.
It allows continued monitoring of the benefit/risk balance of the medicinal product. uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store
Parents of children receiving 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 regrowth usually occurs. Care is required when levothyroxine is administered to patients with known history of epilepsy.
Seizures have been reported rarely in association with the initiation of levothyroxine sodium therapy, and may be related to the effect of thyroid hormone on seizure threshold. Haemodynamic parameters should be monitored when levothyroxine therapy is initiated in very low birth weight preterm neonates as circulatory collapse may occur due to the immature adrenal function.
A small number of patients report adverse events on changing between different levothyroxine products. In some cases, symptoms are reported despite thyroid function tests within the reference range. If patients report side effects on switching between products, consider thyroid function testing.
For patients who are persistently symptomatic after switching, whether they are biochemically euthyroid or have evidence of abnormal thyroid function, consider consistently prescribing a specific levothyroxine product that is well-tolerated by the patient.
If symptoms or poor control of thyroid function persist despite adhering to a specific product, prescription of levothyroxine in an oral solution formulation should be considered. 3). Thyroid hormones should not be given for weight reduction.
In euthyroid patients, treatment with levothyroxine does not cause weight reduction. Substantial doses may cause serious or even life-threatening undesirable effects, particularly in combination with certain substances for weight reduction, and especially with sympathomimetic amines.
Interferences with laboratory test:
Biotin may interfere with thyroid immunoassays that are based on a biotin/streptavidin interaction, leading to either falsely decreased or falsely increased test results. The risk of interference increases with higher doses of biotin.
When interpreting results of laboratory tests, possible biotin interference has to be taken into consideration, especially if a lack of coherence with the clinical presentation is observed. For patients taking biotin-containing products, laboratory personnel should be informed when a thyroid function test is requested.
5). Paediatric population Parents of children receiving 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 subsequently regrowth usually occurs.
Excipients Sodium This medicinal product contains less than 1 mmol sodium (23mg) per tablet, that is to say essentially ‘sodium-free’.