is phenoxybenzamine competitive
Therefore, sometimes these drugs are referred to as sympatholytics because they antagonize sympathetic activity. Some alpha-blockers are non-competitive (e.g., phenoxybenzamine), which greatly prolongs their action, whereas others are relatively selective for one type of alpha-adrenoceptor.Vascular smooth muscle has two types of alpha-adrenoceptors: alpha 1 (Î± 1) and alpha 2 (Î± 2).luid retention is also a problem that can be rectified by use of a diuretic in conjunction with the alpha-blocker. Alpha blockers have not been shown to be beneficial in heart failure or angina, and should not be used in these conditions.