Effect of atenolol or enalapril on diurnal changes of blood pressure in Japanese mild to moderate hypertensives: a double-blind, randomised, crossover trial.

This randomised, double-blind, crossover study compared enalapril 5 mg, and atenolol 50 mg, each dosed once daily for 4 weeks, and investigated casual and diurnal BP changes using 24 hour ambulatory BP monitoring. Both atenolol and enalapril satisfactorily lowered BP during the day and no excessive falls occurred at night. The tendency for BP to increase during the day and decrease at night was maintained during both active periods. Pulse rate was reduced only by atenolol throughout 24 hours. The BP increase observed 2 hours after rising in the morning was suppressed by atenolol but not by enalapril. Both drugs reduced the rates of systolic (greater than or equal to 160 mmHg) and diastolic (greater than or equal to 95 mmHg) BP increases to half of those during placebo. The frequency with which diastolic BP increased above these limits was less during the atenolol period. The difference in BP between a hospital casual reading and the mean 24 hour ambulatory reading was reduced only by atenolol. Furthermore, only atenolol suppressed the BP and pulse rate increases on exercise.