PEBC: What You Need to Know: Levothyroxine

Levothyroxine is a synthetic formulation of T4 thyroid hormone.

Indication: Hypothyroidism

Dosing:

-Once daily on an empty stomach in the morning 30 to 60 minutes before breakfast, or at bedtime on empty stomach

~1.7 mcg/kg/day, otherwise start with low dose in cardiac patients. Adjust dose every 6 to 8 weeks until both TSH, T3 and T4 are within range.

Adverse Effects:

-Well-tolerated if it is the correct dose. If overtreatment, symptoms of hyperthyroidism appear, such as sweating, tremors and fast heartbeat.

-May exacerbate cardiac conditions such as atrial fibrillation, heart failure and MI.

Drug Interactions:

-Chelation with antacids: iron, calcium, aluminum, magnesium - space by 4 hours

-Binders: cholestyramine, sodium polysterene sulfonate, psyllium fibre - separate administration