Effect of Carteolol, Indenolol and Metoprolol On The Thyroid Hormone of Hyperthyroid Patients

Abstract

Thirty-four hyperthyroid patients were divided into four groups : placebo, Carteolol (20 mg/day), indenolol (60 mg/day) and metoprolol (120 mg/day) groups. The heart rate was determined before and two weeks after the treatment with each drug. Serum levels of T4, T3 and rT3 were measured before, and one and two weeks after the treatment. Both indenolol and metoprolol significantly reduced the heart rate (p<0.01 and P<0.05, respectively), whereas Carteolol was ineffective. Carteolol significantly decreased T4 from 23.4 ± 4.4 μg/100ml to 20.1±3.2μg/100 ml (p < 0.01) in one week and to 20.0±3.7 ;tfg/100 ml (p < 0.01) in two weeks. T3 and rT3 were also decreared significantly (P<0.05 and P<0.01, respectively) two weeks after the treatment with Carteolol. After two weeks of indenolol treatment, T4 was decreased significantly from 26.2 ± 8.5 ;Kg/100 ml to 23.9±8.2 μg/100 ml (p < 0.05) and T3 from 789±391ng/100 ml to 592±340 ng/100 ml (P0.02). Metoprolol had no effect on serum thyroid hormone levels. The decrease in the serum level of thyroid hormones by Carteolol and indenolol but not by metoprolol in patients with hyperthyroidism would be due to the blockade of β2-adrenoceptors concerning with thyroid hormone secretion. Carteolol ; indenolol ; metoprolol ; thyroid hormone ; hyperthyroidism cerning the potency of ?-adrenoreceptor blockers, Carteolol is about ten times as potent as propranolol (Nakagawa et al. 1974) and indenolol (Tachikawa and Takenaka 1973). Other non-specific β-adrenoreceptor blockers, Oxprenolol (Jones et al. 1981) and Sotalol (Wahlberg et al. 1976), which had been reported to be ineffective on the serum levels of thyroid hormones, were less potent than propranolol (Frishman 1979). The significant decrease in serum thyroid hormones induced by the treatment with Carteolol would be attributed to its stronger β-adrenoreceptor blocking activity. © 1985, Tohoku University Medical Press. All rights reserved