Fourteen patients (mean age 56.0, range 37-61 years; eight females) with mild essential hypertension (DBP greater than 90 mm Hg on placebo) completed a randomised, double-blind placebo controlled crossover study comparing the hypotensive effects of bisoprolol (10-20 mg) and atenolol (50-100 mg) each taken once daily. 2. Bisoprolol had a significantly greater antihypertensive effect than atenolol, reducing sitting blood pressures by 15.9 mm Hg (diastolic) and 21.9 mm Hg (systolic) compared with placebo. Corresponding figures for atenolol were 10.7 and 5.7 mm Hg respectively. Bisoprolol reduced standing blood pressures by 15.9 mm Hg (diastolic) and 22.8 mm Hg (systolic) compared with 7.3 and 8.6 mm Hg respectively for atenolol. 3. Examination of the pharmacokinetic data showed that bisoprolol had a median elimination half-life of 11.2 h during chronic dosing, compared with 6.4 h for atenolol. For bisoprolol, the median clearance fell from 264 ml min-1 after a single dose to 212 ml min-1 during chronic dosing, although clinically significant accumulation would not be expected during chronic administration. 4. Overall, the results suggest that bisoprolol may be a more effective antihypertensive agent than atenolol but larger studies are necessary to confirm these findings.
