Liotrix
Mechanism :
Liotrix is a synthetic mixture of the thyroid hormones levothyroxine (T4) and liothyronine (T3) in a 4: 1 ratio by weight. Thus, it acts by increasing metabolism of proteins and carbohydrates basal metabolic rate, increasing protein synthesis and increasing gluconeogenesis. Thyroid hormones play an important role in the development of the central nervous system thus administration of liotrix is integral to the treatment of congenital hypothyroidism. It helps reestablish physiologic levels of thyroid hormone,
Indication :
- Hormone replacement therapy in hypothyroidism: congenital or acquired.
Contraindications :
• Thyrotoxicosis
• Adrenal insufficiency
• Hypopituitarism
• Caution in: cardiovascular disease, endocrine disorders, hypertension, diabetes mellitus
• Osteoporosis
• Infertility
Dosing :
Available as tablets of following dosage containing T3 and T4 respectively in the following quantities:
15 mg: 3.1/12.5 mcg
30 mg: 6.25/25 mcg
60 mg: 12.5/50 mcg
120 mg: 25/100 mcg
180 mg: 37.5/150 mcg
Treatment dosage:
0-6 months: 3.1/12.5 mcg to 6.25/25 mcg PO
6-12 months: 6.25/25 mcg to 9.35/37.5 mcg PO
1-5 years: 9.35/37.5 mcg to 12.5/50 mcg PO
6-12 years: 12.5/50 mcg to 18.75/75 mcg PO
>12 years: >18.75/75 mcg PO
Medication should be taken on an empty stomach at least 30-60 minutes before breakfast.
Additionally, the brand/manufacturer of the drug should be maintained and not changed without prior consultation with a physician.
Adverse Effect :
Serious Reactions
• Heart Failure
• Atrial Fibrillation
Common Reactions
• Palpitations
• Tachycardia
• Arrythmia
• Tremor
• Hyperthyroidism
• Thyrotoxicosis
• Rise in blood pressure
• Anxiety
• Urticaria
• Weight loss
• Diarrhea
• Headache
• Chest pain
• Cramps
• Insomnia
Interaction :
Contraindicated
• Sodium Iodide I-131: Concomitant use decreases thyroid gland uptake of sodium iodide I-131 thus reducing efficacy
Monitoring required:
• Didanosine: Concomitant use decreases efficacy of Liotrix by inhibiting its gI absorption
• Insulin aspart/degludec: Liotrix may decrease the efficacy of these drugs
• Levonorgestrel / ethinylestradiol : Concomitant use may decrease the efficacy of Liotrix
• Metformin: Liotrix decreases efficacy of Metformin
• Warfarin: Liotrix increases efficacy of Warfarin
Hepatic Dose :
No specific guidelines available