Chronobiological approach to the treatment of essential hypertension: preliminary data.

The effect on bioperiodic parameters of hypertension elicited by the beta-blocking agent mepindolol, administered as a single dose of 10 mg at 8 a.m. vs 10 mg at 8 p.m., was evaluated in this study. Circadian blood pressure monitoring was performed in age-matched patients with essential hypertension after a two-week wash-out period with placebo and four weeks treatment. Patients were randomly allocated to one of the two treatment groups. Standard blood chemistry and electrocardiogram were performed at the beginning and end of the treatment period. Statistical analysis of blood pressure circadian rhythm characteristics (mesor, amplitude, acrophase) showed a significant decrease of mesor of systolic and diastolic blood pressure in both groups. Values of the mesor were not significantly different between the two groups. Interestingly, changes of acrophase and amplitude induced by the drug were different in regard to the time mepindolol was administered. Side effects were generally mild.