Influence of xamoterol, a partial beta 1-selective agonist, on physical performance capacity and cardiocirculatory, metabolic and hormonal parameters.

In a double-blind, random, cross-over study, 14 healthy male volunteers received xamoterol 200 mg (Corwin; C) twice daily or placebo (P) for two seven-day medication periods to investigate effects on physical performance, cardiocirculatory parameters, metabolism and hormone levels during exercise. An oral glucose tolerance test (OGTT) was also done. C showed a positive inotropic effect up to an exercise intensity of 100 W, corresponding to a heart rate of about 100 beats.min-1. Chronotropic regulation of the heart remained unchanged, but the increase in systolic blood pressure was more pronounced and the catecholamines behaved as after P. From 150 W onwards, C exhibited beta-blocking properties; heart rate was reduced by up to 8 beats.min-1; systolic blood pressure remained unchanged; and the catecholamines showed a more pronounced increase than after P. Diastolic blood pressure behaved almost identically under all test conditions. With the exception of a slightly increased level of free fatty acids at rest, the parameters of physical performance, lipid and carbohydrate metabolism and the hormone levels under all conditions after C showed similar behaviour to that after as P. The findings indicate that physical performance capacity, cardiocirculatory system, metabolism and hormones were not negatively influenced by C.