DIFFERENT EFFECTS OF PROPRANOLOL, ALPRENOLOL, SOTALOL, ATENOLOL AND METOPROLOL ON SERUM T3 AND SERUM rT3 IN HYPERTHYROIDISM

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Abstract
Serum T4 [thyroxine], T3 [triiodothyronine], rT3 [reverse triiodothyronine] and T3 resin uptake (T3 RU) were measured before and after 7 days of treatment with either propranolol, alprenolol, sotalol, atenolol or metoprolol in hyperthyroid patients. A significant decrease in serum T3 was found after propranolol, alprenolol, atenolol and metoprolol but no change in the sotalol treated group. A significant increase in rT3 was found in the propranolol and alprenolol treated groups, while a significant fall in rT3 was found in the atenolol and metoprolol treated groups. No change was found in the sotalol treated group. The changes observed in serum T3 and in rT3 could be explained by an inhibition of the 5''-deiodinase enzyme by propranolol and alprenolol as well as an inhibition of both the 5''-deiodinase and 5-deiodinase enzymes caused by atenolol and metoprolol.