Abrupt change from a beta-adrenoceptor blocking drug to enalapril in hypertension

The haemodynamic and hormonal effects of an elective change of antihypertensive therapy from a beta-adrenoceptor blocking drug to a converting enzyme inhibitor, enalapril, were monitored in 12 hypertensive in-patients (WHO I). Blood pressure and heart rate were determined every 2-4 h using an automatic sphygmomanometer during an abrupt cessation of the previous beta-adrenoceptor blocking drug and commencement of treatment with enalapril 20 mg o.d. 12 h later. Mean blood pressure values at rest and during the hand grip test were lower when on enalapril, but heart rate was significantly higher, and three patients suffered from palpitations during the change. The change resulted in an improvement in cardiac function both at rest and during isometric work, as shown by echocardiography. A rapid decrease in plasma angiotensin converting enzyme (ACE) activity and an increase in renin activity were also seen after the change, while plasma levels of atrial natriuretic peptide (ANP) decreased towards normal values. The results suggest that an abrupt change from a chronic beta-adrenoceptor blocking drug to enalapril is safe, feasible and is likely to produce favourable haemodynamic and hormonal effects in hypertensive patients.