A Double-Blind Comparison of Atenolol (‘Tenormin’) and Methyldopa in the Treatment of Moderate Hypertension in General Practice: A Multicentre Study

Summary

A general practice multi-centre, double-blind crossover study was carried out in 90 patients with mild to moderate hypertension to compare the antihypertensive effect of 50 mg atenolol 3-times daily with that of 250 mg methyldopa 3-times daily. After an initial 4-week standardization period, during which patients originally on a beta-blocker were transferred to atenolol and patients on methyldopa continued at the standardized trial dosage, patients were given each trial drug, in random order, for 4 weeks. All then received 100 mg atenolol daily for a further 8 weeks. During the double-blind phase of the trial, there was no statistically significant difference between blood pressure control attained by atenolol and that achieved by methyldopa. At the end of the open phase, however, it was found that the diastolic pressure was significantly lower than that produced during the double-blind phase by either drug. Pulse rate during atenolol treatment was significantly lower than it was during treatment with methyldopa. Body weight, blood urea, serum sodium, potassium and bicarbonate, haemoglobin, and white and red cell counts remained within normal limits throughout the trial. Atenolol was well-tolerated, and there was no significant difference in the incidence of side-effects caused by the two drugs. Complaints elicited by a questionnaire during the double-blind phase were all of a minor nature.

The results suggest that blood pressure control with 50 mg atenolol 3-times a day was at least as good as that achieved with 250 mg methyldopa at a similar dosage frequency. The open phase showed that 100 mg atenolol given once daily can produce a significant fall in blood pressure in patients poorly controlled by other antihypertensive agents. It is suggested, therefore, that atenolol provides a simple and effective alternative to methyldopa in the treatment of hypertension.

Key Words::

• Atenolol
• adrenergic beta receptor blockaders
• antihypertensive agents
• hypertension - methyldopa