A comparison of the effects of the slow release formulations of metoprolol and oxprenolol in hypertension

Abstract

The therapeutic control of blood pressure and heart rate throughout the 24 hour period, was assessed in ten hypertensive patients, following the administration of placebo, conventional metoprolol 100 mg twelve hourly, and the slow release formulations of metoprolol (metoprolol S.A.) and oxprenolol (oxprenolol S.R.), given once daily. Good blood pressure control at rest was observed at two hours post dose following the three drug regimes. Analysis of blood pressure and heart rate values in response to exercise showed no difference between conventional and metoprolol S.A. at either two hours or 12/24 hours post dose. However, at 24 hours, metoprolol S.A. gave better clinical control of the systolic blood pressure and heart rate than oxprenolol S.R. with metoprolol inhibiting exercise induced tachycardia by 29% at 2 hours and 20% at 24 hours (oxprenolol 24% and 11% respectively). In this study, metoprolol S.A. was effective in the control of hypertension throughout the 24 hours period, both at rest and during exercise. The control at 24 hours by oxprenolol S.R. was poor and suggests that the present formulation should be reconsidered.