RESUMO
In a double-blind, randomised, cross-over study, the pharmacokinetic/dynamic effects and subjective symptoms of a new controlled-release (CR) formulation of metoprolol (50 and 100 mg) have been compared with atenolol (50 mg) and placebo in 20 elderly healthy subjects. The metoprolol CR formulation displayed an even plasma concentration-time profile over the dosage interval while atenolol produced a peak at 2-4 h. All three active treatments produced significant beta 1-blockade at 24 h compared to placebo. Four hours after dose intake, the degree of beta 1-blockade was significantly greater with conventional atenolol 50 mg than with either dose of metoprolol CR. Subjective well-being was examined with a self-administered questionnaire (MSE-profile), including three dimensions: Contentment, Vitality and Sleep. No significant differences were detected between placebo and either dose of metoprolol CR. At 2 h, following atenolol, a deterioration in Vitality was observed compared to placebo and metoprolol CR 100 mg. At the end of the dosage interval there was no longer any significant difference between the treatments. Perceived leg fatigue during exercise, evaluated 4 h after dosing, was more pronounced during treatment with atenolol than metoprolol CR 50 mg. The results suggest that the metoprolol CR formulation was not associated with significant effects on subjective well-being, whereas atenolol caused a deterioration at the time of the peak plasma concentration of the drug.
