In a double-blind, cross-over and placebo-controlled study seven patients were given carbimazole plus either placebo or propranolol (40 mg) for 1 month and then switched to the alternative adjunct treatment for a further month 1. One month after the baseline, the mean improvements in heart rate were 23% in the carbimazole + placebo group and 38% in the carbimazole + propranolol group. Tremor also improved during the 1st month of the study by 31% in the carbimazole + placebo group versus 59% in the carbimazole + propranolol group. Whereas further improvements were observed in both variables in those receiving propranolol as the second adjunct treatment, this was not the case in those who received placebo during the same period.
Twenty hyperthyroid patients were randomly assigned in a double-blind fashion to receive either nadolol 80 mg/day or placebo for 2 weeks 3; all patients then took carbimazole as well from 2-6 weeks. Twenty-four hour Holter ECG recordings at 0, 2 and 6 weeks showed that nadolol reduced the mean maximum heart rate by 19.9% (P less than 0.0005) at 2 weeks and by 30.3% (P less than 0.0005) at 6 weeks compared to 5.2% (ns) and 18.3% (P less than 0.0005) in patients taking placebo.
Whole-body oxygen consumption and carbon dioxide production was measured in a semiopen canopy system with paramagnetic O2 and infrared CO2 sensors in a randomized trial comparing tiamazole, propranolol, and metoprolol 2. Tiamazole normalized oxygen consumption and induced signs of anabolism with improved nutritional state. Metroprolol did not affect oxygen consumption. Propranolol reduced elevated oxygen consumption by 54%. Body weight and other anthropometric assessments were stable after specific and nonspecific beta-blockade, which also led to symptomatic relief in approximately 90% of the patients.
Comment: The quality of evidence is downgraded by sparse data.
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