Beta 2-adrenoceptor agonists and thyroid hormones.

The potential influence of the selective beta 2-adrenoceptor agonist terbutaline on the serum concentration of the thyroid hormones in humans was studied in 11 healthy euthyroid subjects. Five served as a control group without medication while six received 5 mg terbutaline three times daily for 2 weeks. No significant differences were found between the two groups by measuring the serum concentrations of thyroxine, triiodothyronine, reverse triiodothyronine and resin-triiodothyronine uptake. The use of a beta 2-adrenergic receptor stimulating drug is relatively contraindicated in untreated thyrotoxicosis. This recommendation is based upon a summation of clinical adverse reactions and not due to an effect on the serum concentrations of thyroid hormones.