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Updated 2 Feb 2023 | Thyroid hormones


Powder for solution for injection containing 20micrograms liothyronine sodium.

Drugs List

  • liothyronine 20microgram powder for solution for injection
  • Therapeutic Indications


    Treatment of hypothyroid coma, usually in conjunction with other measures including the intravenous injection of a corticosteroid.

    Oral liothyronine treatment is recommended for the treatment of less severe forms of hypothyroidism and for maintenance therapy.
    Liothyronine may be preferred for treating severe and acute hypothyroid states because of its rapid and more potent effect, but levothyroxine sodium is normally the drug of choice for routine replacement therapy.


    This monograph relates only to the specific indications and doses of the liothyronine injection The separate monograph for the tablets should be consulted for further information.


    5 to 20 micrograms given by slow intravenous injection and repeated at intervals of 12 hours or less if required. The minimal interval between dosing is 4 hours.
    Initial dose: 50 micrograms intravenously.
    Maintenance dose: Further intravenous injections of 25 micrograms every 8 hours until improvement occurs. Then reduce dose to 25 micrograms intravenously twice daily.


    Smaller initial doses are recommended in elderly patients.


    The injection is not licensed for use in children under 18 years of age.

    Hypothyroidism (as a replacement for oral levothyroxine) (unlicensed)
    Convert daily levothyroxine dose to liothyronine (20 to 25 micrograms liothyronine is equivalent to approximately 100 micrograms levothyroxine) and give in two to three divided doses by slow intravenous injection. Titrate according to response.

    Hypothyroid coma (unlicensed)
    Children aged 12 to 18 years
    5 to 20 micrograms by slow intravenous injection, repeated every 12 hours. Can be increased to every 4 hours if necessary.
    Initial dose: 50 micrograms as a single dose.
    Maintenance dose: Follow by doses of 25 micrograms every 8 hours. Reduce dose to 25 micrograms twice daily.


    Injections should be given intravenously, as the alkalinity of the solution may cause irritation of the tissues if given by deep intramuscular injection.


    The solution is prepared by adding 1 or 2ml water of injection to the powder, and shaking gently until the solution has dissolved.


    Cardiovascular disease
    Exertional angina
    Children under 12 years

    Precautions and Warnings

    Severe and prolonged hypothyroidism may lead to decreased adrenocortical activity. When thyroid replacement therapy is started, metabolism may be raised at a greater rate than adrenocortical activity which can lead to adrenocortical insufficiency requiring supplemental adrenocortical steroids. Additional caution is required in panhypopituitarism and any patient with a predisposition to adrenal insufficiency (initiate corticosteroids prior to liothyronine).

    Care must be taken to avoid excessive burden on cardiac muscle affected by prolonged severe thyroid depletion. An ECG performed prior to starting treatment can help to distinguish between underlying myocardial ischaemia from changes induced by hypothyroidism. Start therapy with lower initial doses, smaller increments and longer intervals between dose increases as necessary.

    Liothyronine must be given with extreme caution in hypothyroid coma because too large a dose can precipitate heart failure, especially in the elderly patients and those with ischaemic heart disease. ECG monitoring can give a useful indication of impending ischaemia, however, changes in ST segment can be confused with similar changes occurring in hypothyroidism.

    Thyroid replacement therapy should be introduced very gradually in elderly patients and those with long-standing hypothyroidism to avoid any sudden increase in metabolic demands. If metabolism increases too rapidly (causing diarrhoea, nervousness, rapid pulse, insomnia, tremors and sometimes anginal pain) dosage should be reduced or withheld for a period of 1 - 2 days. Treatment should then resume at a lower dose.

    Liothyronine treatment may result in an increase in insulin or anti-diabetic drug requirements. Care is required for patients with diabetes mellitus and diabetes insipidus.

    Children 12 - 18 years (see Dosage; Children)

    Pregnancy and Lactation


    Liothyronine is a naturally occurring hormone produced by the mother and her foetus. Liothyronine is used during pregnancy for the treatment of hypothyroidism. Thyroid hormones do not readily cross the placenta

    Untreated or undertreated maternal hypothyroidism is associated with low birth weight, pre-eclampsia, placental abruption and lower neuropsychological development of the child. Monitor maternal thyroid function, dose adjustment may be necessary.

    The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14-17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( ) or if this is unavailable at the backup site ( ).


    Liothyronine is excreted into breast milk in small amounts but effects on the nursing infant are not thought to be physiologically significant. Concentrations in milk are too low to protect a hypothyroid infant from the effects of the disease.

    The amount excreted in breast milk is believed to be too small to interfere with neonatal screening for hypothyroidism.

    Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
    Specialist advice is available from the UK Drugs in Lactation Advisory Service at

    Effects on Ability to Drive and Operate Machinery

    None known.

    Side Effects

    The following effects are indicative of excessive dosage and usually disappear on reduction of dosage or withdrawal of treatment for a day or two.

    Cardiac arrhythmias
    Muscular cramps
    Weight loss
    Heat intolerance
    Menstrual disturbances

    Hypersensitivity reactions
    Hair loss (transient)
    Benign intracranial hypertension
    Premature closure of epiphyses


    It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.

    The following number will direct the caller to the relevant local centre (0844) 892 0111

    Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( ) or if this is unavailable at the backup site ( ).

    Shelf Life and Storage

    Store below 25 degrees C.
    Protect from light.

    Further Information

    Last Full Review Date: February 2012

    Reference Sources

    Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment, 2nd edition (2007) ed. Schaefer, C., Peters, P. and Miller, R. Elsevier, London.

    Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk, 9th edition (2011) ed. Briggs, G., Freeman, R. and Yaffe, S. Lippincott Williams & Wilkins, Philadelphia.

    Martindale: The Complete Drug Reference, 37th edition (2011) ed. Sweetman, S. Pharmaceutical Press, London.

    Summary of Product Characteristics: Liothyronine Sodium 20 micrograms Injection. Goldshield Pharmaceuticals. Revised January 2011.

    Summary of Product Characteristics: Liothyronine Sodium 20 micrograms Tablets. Goldshield Pharmaceuticals. Revised May 2011.

    NICE Evidence Services Available at: Last accessed: 17 August 2017

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