Pharmacotherapy Newsletter

Volume 1, Issue 8, 03/09/2009

Question

Why do clinicians prefer to use propranolol in patients who are experiencing thyrotoxicosis, or thyroid storm, versus other beta-blockers?

Answer

Patients experiencing thyrotoxicosis (thyroid storm), or symptomatic hyperthyroidism, can experience a number of effects that can include tachycardia, palpitations, tremor and/or nervousness.  Patient's with this condition are known to have an increased production of the thyroid hormones, thyroxine (T4) and 3,5,3'-triiodothyronine (T3).  While the thyroid gland primarily releases T4 into the circulation, T4 is generally metabolized to T3 in the peripheral tissue by two enzymes: monodeiodinase type I (5'D-I) and monodeiodinase type II (5'D-II).  The production of T3 is important because it is more biologically potent than T4.¹