The vasodilator--beta-blocker interaction--some determinants of its clinical success.

A number of structurally dissimilar compounds, sharing the ability to induce vasodilatation have come into clinical usefulness as antihypertensive drugs. Their successful utilisation often depends critically on an appropriate combination with diuretics and beta-blockers. Beta-blockers can specifically inhibit the reflex cardiac stimulation which otherwise may limit the tolerability and haemodynamic value of these drugs. A synergistic antihypertensive effect has been demonstrated with hydrallazine and propranolol and possibly exists with other combinations. Generally, vasodilators are not first-line drugs in chronic therapy but are best added to beta-blockers. Variations of the dose-response and the time-course of effect are stressed as being important determinants of a successful interaction.