Liothyronine Sodium

Registered South African indications:

• Myxoedema coma
• Severe chronic thyroid deficiency
• Hypothyroid states arising in the treatment of thyrotoxicosis
• Thyrotoxicosis (as an adjunct and diagnostic test)

Contraindications 

• Hypersensitivity to the active ingredient or any of its excipients
• Angina of effort or cardiovascular disorders
• Untreated adrenal cortical insufficiency
• Untreated hyperthyroidism

Cautions 

• Pregnancy
• Breastfeeding
• Renal impairment
• Hepatic impairment
• Elderly
• Severe and/or prolonged hypothyroidism
• Diabetes mellitus
• Diabetes insipidus
• Predisposition to adrenal insufficiency
• Risk of occult cardiovascular disease
• Panhypopituitarism
• Galactose intolerance
• Lapp lactase deficiency
• Glucose-galactose malabsorption

Forms avail. in SA and covered in this monograph: tab 

Severe chronic thyroid deficiency
Hypothyroid states secondary in the treatment of thyrotoxicosis

• Oral (tab): Initial: 10-20μg, 8hrly; Up-titrate if necessary after 7 days; Maintenance: 60μg in 2-3 divided doses

Myxoedema coma

• Oral (tab): Initial: 60μg; Then: 20μg, 8hrly, via stomach tube

Thyrotoxicosis (additional agent required)
- As an adjunct

• Oral (tab): 20μg, 8hrly

Thyrotoxicosis
- Diagnostic test

• Oral (tab): 75-100μg/day, in 3-4 divided doses; Treatment duration: 7-8 days

Determine radioactive iodide uptake before and after administration. Failure to suppress the uptake of the radioactive iodide is indicative of thyrotoxicosis

See Additional Prescribing Points 

Paed. forms avail. in SA and covered in this monograph: tab 

Severe chronic thyroid deficiency
Hypothyroid states secondary in the treatment of thyrotoxicosis

Younger than 12 years

• Oral (tab): Initial: 5μg, dly

Between 12-17 years

• Oral (tab): Initial: 10-20μg, dly; Maintenance: 60μg, dly in 2-3 divided doses

Tablets can be crushed and titrated with lactose for administration as a powder

See Additional Prescribing Points 

Pregnancy 

• Caution
• Safety during pregnancy is not known. The risk of congenital abnormalities should be weighed against the risk to the foetus of untreated maternal hypothyroidism

Breastfeeding

• Caution 
• Liothyronine sodium is excreted into breast milk in low concentrations. This may interfere with neonatal screening programmes
• The decision to breastfeed during liothyronine sodium treatment should be weighed against the risk of infant exposure, the benefits of breastfeeding to the infant, and benefits of treatment to the mother

Fertility

• No human or animal data on the effect of active substance liothyronine on fertility are available

Renal Impairment 

• Caution; no information available 
  Liothyronine is substantially excreted by the kidney

Hepatic Impairment

• Caution; no information available

Elderly 

• Caution; dose adjustment recommended
  For treatment of hypothyroidism:
  Oral (tab): Initial: 5μg, dly; Titrate by increments of 5μg/day every 14 days
  For treatment of myxoedema coma and suppression test:
  Refer to adult dosing; use with caution and initiate at the low end of the dosing range

Porphyria Information

• Not porphyrinogenic (NP)

Drugs in Sport

• Permitted - No warnings

Central Nervous System Disorders

• Restlessness
• Excitability
• Headache
• Tremor
• Insomnia

Cardiovascular Disorders

• Anginal pain
• Cardiac arrhythmias
• Palpitations
• Tachycardia

Gastrointestinal Disorders

• Vomiting
• Diarrhoea

Endocrine and Metabolic Disorders

• Heat intolerance
• Excessive loss of weight
• Adrenocortical insufficiency

Musculoskeletal Disorders

• Muscle weakness
• Muscle cramps

Skin and Subcutaneous Tissue Disorders

• Rash
• Pruritus
• Oedema
• Transient hair loss in children
• Sweating
• Flushing

Immune, Blood and Lymphatic System Disorders

• Hypersensitivity reactions
• Fever

• Anticoagulants
• Anticonvulsants
• Phenytoin
• Carbamazepine
• Cardiac glycosides
• Cholestyramine
• Colestipol
• Antidiabetic agents
• Insulin
• Tricyclic antidepressants
• Amitriptyline
• Imipramine
• Oral contraceptives
• Amiodarone
• Oestrogens
• Primidone
• Barbiturates

• Thyroid stimulating hormone
• Thyroid function
• Heart rate
• Blood pressure
• ECG

None routine. Specific cases may require 

• Bone mineral density

Difficulty in swallowing tablets

• For patients who have difficulty swallowing whole tablets such as the elderly and young children, a whole tablet may be crushed and allowed to dissolve, with swirling, in a minimum of 20ml of water for 5 minutes. The entire volume of liquid should be consumed

Propylthiouracil (PTU) treatment

• Liothyronine rather than levothyroxine would be the replacement therapy of choice during block and replace treatment of thyrotoxicosis with propylthiouracil (PTU) due to the inhibition of PTU of the peripheral conversion of T4 to T3

Liothyronine sodium is a naturally occurring thyroid hormone. The biological action of liothyronine sodium is quantitatively similar to that of levothyroxine sodium, but the effects develop in a few hours and disappear within 24-48 hours of stopping treatment.

Tablet 20μg

• Tertroxin (Pharmacare)