beta-blockers have been accepted as a reasonable adjunct
therapy for the treatment of
hyperthyroidism. They lessen the sympathetic symptoms such as
tachycardia and finger
tremor. On the other hand, many studies have demonstrated a decrease in 3, 3', 5-triiodothyronine (T3) during treatment with beta-blockers (especially
propranolol). The purpose of this study is to clarify the effect of
arotinolol (alpha 1, beta-blocker) on the thyroid functions and autonomic nerve systems (ANS) of patients with
Graves' disease.
Arotinolol 20mg a day p.o. was given to untreated patients with
Graves' disease (n = 16) for 2 weeks. Blood sampling and the ANS function-tests were done before and after the treatment. In addition, the in vitro effects of
arotinolol on the cAMP production and the radioactive
iodine uptake (RAIU) using rat thyroid cell line FRTL5 were evaluated to examine the direct influence on thyroid cells.
Arotinolol improved
hyperthyroid symptoms including
tachycardia, but had no effect on ANS function-tests. It is of interest that not only T3 but also T4 decreased after the
arotinolol treatment. We therefore suspected the direct suppressive effects of
arotinolol on the thyroid. There were, however, no in vitro inhibitory effects on the cAMP production and the RAIU in TSH-stimulated FRTL5 cells. The reason why serum T4 levels in patients with untreated
Graves' disease have decreased after the treatment of
arotinolol could not be clarified. In conclusion,
arotinolol is a very useful
drug for the initial
therapy of patients with
Graves' disease to reduce the serum
thyroid hormone levels and symptoms of
hyperthyroidism when combined with
antithyroid drugs.