Propranolol in the treatment of thyrotoxicosis: a review

The clinical manifestations of hyperthyroidism have suggested to physicians for many years that the sympathetic nervous system may be involved in their production. Despite this, the precise interrelationship between the thyroid gland and the sympathetic nervous system has never been defined but controlled investigations have shown that hypersensitivity to catcholamines does not occur in animals or man with artificially produced thyrotoxicosis. In recent years beta-adrenoceptor blocking drugs, and in particular propranolol, have been used in patients with hyperthyroidism. Evidence exists that they control some of the peripheral manifestations of the disease, including nervousness, palpitations, tachycardia, increased cardiac output and tremor, but they do not appear to affect the underlying thyrotoxic process itself. Propranolol has been used with sucess in the treatment of acute hyperthyroid crisis, in pre-operative preparations for thyroidectomy, for the control of symptoms and signs following the administration of radioactive iodine therapy and antithyroid drugs, during the period of diagnostic thyroid investigations and occasionally as the sole therapy. The supportive role of propranolol in the management of hyperthyroidism is now established and in some instances such as radioactive iodine therapy, it has enabled improvements in the existing methods of treatment to be achieved.