FDA approved Levothyroxine Sodium for Injection for Myxedema ComaFDA approved injectable thyroid drug for life threatening coma condition

Levothyroxine Sodium is an L-thyroxine (T4) product. It produces a gradual increase in circulating concentrations of thyroid hormone with an approximate half-life of 9 to 10 days in hypothyroid patients.

Levothyroxine Sodium for Injection is indicated for the treatment of myxedema coma. Important limitations: The relative bioavailability between this injectable and oral levothyroxine products has not been established. Caution should be used when switching patients from oral to intravenous levothyroxine as accurate dosing conversion has not been studied.

Initial intravenous loading dose: 300 to 500 mcg, followed by once daily intravenous maintenance doses between 50 and 100 mcg, administered as clinically indicated until the patient can tolerate oral therapy. Consider age, general physical condition, cardiac risk factors, and clinical severity of myxedema when determining dosages. For chronic treatment of hypothyroidism, an oral dosage form should be used. Reconstitute by aseptically adding 5 mL of 0.9% Sodium Chloride Injection, USP. Shake vial to ensure complete mixing. Reconstituted solution is preservative free and stable for 4 hours. Discard any unused portion. Do not add to other IV fluids.

Trial data not available in label.

Intravenous levothyroxine may be associated with cardiac toxicity including arrhythmias, tachycardia, myocardial ischemia and infarction, or worsening of congestive heart failure and death in the elderly and in those with underlying cardiovascular disease. Cautious use, including doses in the lower end of the recommended range, may be warranted in these populations.

Levothyroxine Sodium for Injection is indicated specifically for myxedema coma when oral therapy is not tolerated. Due to unestablished bioavailability, careful monitoring and dose adjustment are required when transitioning to oral levothyroxine.