Comparison of propranolol and carbimazole as adjuncts to iodine-131 therapy of hyperthyroidism

Abstract

Abstract. Seventy thyrotoxic patients were treated with carbimazole (36 patients) or propranolol (34 patients) prior to and for 6 weeks after a therapeutic dose of 131I. The therapeutic response was evaluated on the basis of the serum free thyroxine index (FT4I) value and the thyrotoxicosis therapy-index (TTI) of Crooks et al. (1960b). Propranolol alleviated many symptoms and signs (palpitations, hyperkinesia, finger tremor, resting pulse rate) as effectively as carbimazole, whereas others (dyspnoea on effort, tiredness, heat intolerance, sweating, nervousness, bodyweight) were not equally affected. Biochemical euthyroidism was achieved significantly slower in the propranolol group (after 100.6 ± 40.5 days vs. 48.5 ± 24.0 days in the carbimazole group) although the dose of 131I was administered after a mean interval of 22 days from the start of treatment in the propranolol group and after 66 days in the carbimazole group. Between 2 and 6 months after 131I the FT4I and TTI followed a similar course in both treatment groups. As judged from the TTI scores 2 weeks after the 131I-therapy no evident aggravation of hyperthyroidism occurred in either group of patients. However, one patient in each group showed marked exacerbation of symptoms which was due to inadequate dosage of the drugs. It is concluded that propranolol, given prior to radioactive iodine, is equally effective as carbimazole in preventing aggravation of thyrotoxicosis after the administration of 131I. In the propranolol-treated patients the tests of thyroid function are more reliable during the drug therapy, but the slow development of euthyroidism may be of clinical importance in patients presenting with severe symptoms.

The Action of Methimazole andL-Thyroxine in Radioiodine Therapy: A Prospective Study on the Incidence of Hypothyroidism

“…Aros et al (30) previously reported that propranolol was equally as effective as carbimazole in controlling thyrotoxic symptoms during RAI therapy. Cure with RAI cannot be achieved quickly as there is a latent period for the full action of radiation to take effect.…”

Low-Dose Radioiodine Given Six-Monthly in Graves' Disease

“…The incidence of hypothyroidism in the first year appears particularly low and some workers have suggested that pretreatment with antithyroid drugs may reduce the incidence of early hypothyroidism (Aro et al 1981, Connell et al 1984. One of the 3 patients who became hypothyroid in the first year had had no previous treatment; the other 2 had received carbimazole for six and seven months respectively.…”

Short-Term Effects of β-adrenergic Antagonists and Methimazole in New-Onset Thyrotoxicosis Caused by Graves' Disease

“…β-blockers provide significant symptomatic relief when used alone in transient thyrotoxicosis conditions such as destructive thyroiditis (4). They are also used in preparation for surgical management or as adjuncts to radioiodine in patients with Graves' disease (GD), the main cause of thyrotoxicosis (1,5). Although it has been established that β-blockers are effective for treating severe hyperthyroidism and thyroid storm (6), the efficacy of β-blockers as adjuncts to anti-thyroid drugs has not been proven (7).…”