[Effect of celiprolol compared to propranolol on thyroid metabolism]

In series of 20 patients suffering from atrial arrhythmias, hypertension or hyperkinetic heart syndrome in euthyroid subjects the effect of the new cardioselective beta-blocker celiprolol was examined when orally administered in doses of 300 mg per day against propranolol in a dosage of 160 mg per day. Celiprolol caused a significant reduction (p less than 0.01) of both systolic and diastolic blood pressure while propranolol showed simply a marked decrease in systolic blood pressure. A significant decrease in heart rate was observed with both drugs (p less than 0.01). TT3 and TT4 decreased only slightly when administering either celiprolol or propranolol. A further not significant drop in FT4 due to celiprolol is contrasted to a similarly not significant increase in FT4 when administering propranolol. A striking decrease in FT3 was induced by both drugs, although in the case of celiprolol this reduction became apparent only within a period of 3 weeks. Since only in cases of hyperthyroidism the number of beta-receptors has increased, the reduction of 5'deiodinase is possibly not so pronounced in euthyroidism. In this way an explanation may be found for a mild inhibition of conversion and a consequently missing increase in RT3. Neither celiprolol nor propranolol caused significant changes of laboratory findings, especially when considering triglycerides and creatinine values. Side effects could be lessened in nearly all cases and deterioration was not observed so that therapy never had to be discontinued. Celiprolol has to be considered as a further favourable cardioselective beta-blocker with intrinsic sympathicomimetic activity, causing a reasonable reduction in blood pressure and heart rate and moreover a propranolol-like effect in the peripheral metabolism of thyroid hormones in euthyroid patients.