Metoprolol or atenolol for mild-to-moderate hypertension

Comparison of the duration of antihypertensive action of atenolol and metoprolol over a 24-hour period

The antihypertensive and beta-blocking effect of 100 mg atenolol and 100 mg metoprolol each given once daily were compared using an observer-blind, randomized, placebo-controlled crossover study. Blood pressure and heart rate were measured 22 hours after the last tablet of a 2-week dosing period. Twenty-five patients completed the study. Both drugs caused a significant decrease in supine and standing blood pressure, with atenolol effecting, numerically, the greater reductions. The decrease in standing diastolic blood pressure was significantly greater with atenolol than with metoprolol (p less than 0.05). Metoprolol at 22 hours post-dosing did not differ from placebo in the control of exercise systolic blood pressure (191.1 v 194.6 mmHg): the exercise systolic blood pressure achieved on atenolol (177.3 mmHg) was significantly lower than that achieved on both placebo (p less than 0.001) or metoprolol (p less than 0.05). The heart rates achieved on atenolol were significantly lower than those achieved on metoprolol in similar circumstances (p less than 0.001). It is concluded that, at the doses examined in this study, atenolol is the more suitable agent for the control of supine, standing and exercise blood pressure over 22 hours.

Asthma and beta-blockers

In a randomized, blind crossover study in 14 hypertensive patients with asthma, involving placebo and chronically administered (3 weeks) equipotent beta1-blocking doses of atenolol 100 mg once daily and metoprolol 100 mg bid, atenolol and metoprolol produced a similar fall in blood pressure. Atenolol caused significantly (p less than 0.05) less bronchospasm in terms of fewer asthmatic attacks, more asthma-free days, less frequent sensations of moderate to very severe, wheeziness and less effect on the evening peak flow rate. It was concluded that, in patients with asthma who require beta blockade, atenolol is the preferred agent, co-prescribed with a beta2 stimulant.

Antihypertensive activity of once daily metoprolol alone and with chlorthalidone and comparison with a twice daily regimen

In a multicentre, double-blind (DB), within-patient study, the antihypertensive effectiveness and tolerability of two oral administration schedules of metoprolol (M) 100 mg b.i.d. versus 200 mg once daily (o.d.), were investigated in 103 outpatients with mild to moderate essential hypertension. The study lasted 14 weeks and was divided into 3 periods: a) a weeks of single-blind (SB) placebo wash-out; b) 4 weeks of SB administration of M 100 mg b.i.d.; at the end of the second week of this period, chlorthalidone (C) 25 mg was added in patients with a recumbent diastolic blood pressure (BP) still greater than 95 mmHg and was continued throughout the following period; and c) DB cross-over administration of M 200 mg/d for 4 weeks on a b.i.d. schedule and 4 weeks on a once daily schedule. In comparison with pretreatment values, heart rate and systolic and diastolic BP were reduced (p less than 0.001) by both M administration schedules; there was no differences between the once and twice daily treatment regimens. During M once daily, betablockade was still maintained over 24 hours or longer, as the heart rate remained significantly lower than the basal value. In 57 patients, C was added at the end of the second week of SB M administration, and a further decrease in BP was observed; again, there was no significant change during once and twice daily M administration. Unwanted effects during M treatment were of minor severity, and the majority occurred when C, too, was added.

Haemodynamic effects of metoprolol and pindolol: a comparison in hypertensive patients

1 In a double-blind study, 36 patients with essential hypertension were randomly allocated to treatment with either metoprolol, 100--300 mg/day, or pindolol, 5--15 mg/day for 6 months. Haemodynamic investigations were made on three separate occasions. Blood flow in the calves and in the forearm was determined by venous occlusion plethysmography after 6 weeks of placebo, after 6 weeks and again after 6 months of active therapy. 2 Both drugs reduced blood pressure significantly, by 17.1/11.8 mm Hg with metoprolol and 21.9/10.9 mm Hg with pindolol after 6 weeks (P less than 0.005). No further changes were seen after 6 months. 3 Heart rate after 6 weeks was significantly reduced by metoprolol (10.7 +/- 2.4 beats/min, P less than 0.001) but not by pindolol (4.4 +/- 2.3 beats/min, NS). After 6 months a significant reduction was seen also in the pindolol group (5.2 +/- 2.1 beats/min, P less than 0.05). 4 The vascular resistance in the calves at rest was reduced by pindolol (P less than 0.05), whereas resistance tended to increase with metoprolol. 5 Resting vascular resistance in the forearm after 6 months was significantly reduced in the metoprolol group (P less than 0.001) as well as in the pindolol group (P less than 0.02). The increase in forearm vascular resistance seen during leg exercise was not influenced by either drug. 6 Vascular resistance at maximal vasodilatation was unchanged in the calves, but a significant reduction (-17.4 +/- 5.7%, P less than 0.01) in the forearm vascular bed was seen after 6 months of pindolol. No change was observed with metoprolol. 7 It is concluded that pindolol reduces elevated blood pressure partly through peripheral vascular mechanism. Metoprolol, on the other hand, probably acts mainly via central cardiac mechanisms.

Comparative study of atenolol, metoprolol, metoprolol durules, and slow-release oxprenolol in essential hypertension

Twenty-five patients with moderate essential hypertension (standing diastolic blood pressure 100-125 mmHg, phase 5) completed a single-blind placebo-controlled cross-over study comparing four week periods of treatment with atenolol 100 mg, metoprolol 100 mg, metoprolol durules 200 mg, slow-release oxprenolol 160 mg, and slow-release oxprenolol 320 mg respectively. All the drugs were significantly better than placebo at reducing resting blood pressure at 24 hours. Atenolol produced the greatest mean reduction of pressure and was the most effective drug for most patients, though the differences between atenolol and metoprolol durules were not statistically significant. These two drugs, however, were significantly more effective than the remainder. A similar ranking was seen with respect to the reduction of the blood pressure and heart rate response to exercise. None of the treatments had any significant effect on the patients' rating of perceived exertion during the exercise test.