Alternative schedules of levothyroxine administration.

Purpose: Published evidence on bedtime versus prebreakfast administration of levothyroxine is reviewed.

Summary: Because levothyroxine absorption has been shown to increase when the drug is administered to patients in a fasted state, the standard recommendation is that levothyroxine be taken one half to one hour prior to breakfast and at least four hours before or after potentially interacting drugs. However, compliance with this recommendation may be problematic for patients with unpredictable or variable schedules.