EFFETTO DEL NADOLOLO NELL'IPERTIROIDISMO

Long-acting beta-blockers have been recently experimentally in hyperthyroidism. Besides the effects on the sympathetic system some of these beta-blockers seem also to modify the concentration of T3 and reverse T3. In this study, we evaluated the effect of a chronic administration of nadolol, a long-acting beta-blocker on the sympathetic symptoms (tachycardia, tremors, hyperhidrosis) and on the hormonal parameters in 10 patients with hyperthyroidism. Nadolol demonstrated an ability to significantly reduce the increased heart rate and all the other symptoms which are correlated to an increased sympathetic activity: also the levels of T4 became significantly reduced, the reduction of reverse T3 was at the limit of significance, while T3, free T3 and free T4 did not significantly change. Nadolol, thanks to its greater half-life and to its greater stability in plasma seems to be a valid alternative to propranolol in the symptomatic treatment of hyperthyroidism. The hormonal changes induced could probably be explained by the fact that nadolol may act on the binding proteins rather than on the conversion of T3 in reverse T3.