Nebivolol versus metoprolol: Effects on fatigue scores and exercise treadmill time

The purpose of this study was to compare the effect of nebivolol, a vasodilating beta-blocker, versus metoprolol, on fatigue score and maximal treadmill exercise time. 31 subjects completed the protocol; 29 were on antihypertensive medication at entry, including 10 on beta-blocker monotherapy, 17 on beta-blocker + other agents, and 2 on medications other than a beta-blocker. Beta-blockers were stopped at entry and replaced by the study drugs; other antihypertensive medications were maintained unchanged throughout the study. In a double-blinded study, metoprolol and nebivolol were given, in randomized order, for 8 weeks each, with each given for 4 weeks at a lower dose (50 mg and 5 mg daily, respectively), and then 4 weeks at a higher dose (100 mg and 10 mg, respectively). At 4 and 8 weeks on each drug, BP, HR, maximal exercise HR and BP, MAF (Multidimensional Assessment of Fatigue) global fatigue index, and Vitality score on the SF-36 Quality of Life questionnaire were assessed. At 8 weeks, echocardiography and applanation tonometry were also performed. At the most widely used doses of metoprolol and nebivolol, there were few significant differences in HR, BP, exercise duration, or fatigue scores between the two drugs. Only maximum exercise HR at 8 weeks was lower for nebivolol compared to metoprolol (P = 0.006). Resting DBP, Central SBP, and Central DBP at 8 weeks were all slightly lower with nebivolol, with borderline significance (P = 0.05, P = 0.07, and P = 0.06, respectively). The results of this study do not rule out the existence of differences in fatigue or treadmill time among individuals who have experienced fatigue while taking beta-blockers.