- Old but powerful α-blocker, is a haloalylamine that blocks α1- and α2- receptors irreversibly.
- It is capable of blocking acetylcholine, histamine, and serotonin receptors, its
primary pharmacological effects, especially that of vasodilation, may be attributed to its α-adrenergic blocking capability.
- Administration is frequently associated with tachycardia, increased cardiac output and
- Onset of action is slow, but the effect of single dose of drug may last 3 to 4 days.
- Principal peripheral effects following its administration are an increase in systemic
blood flow, increase in skin temperature, and a lowering of blood pressure.
- It has no effect on parasympathetic system and little effect on the gastrointestinal tract.
- Most common side effects are miosis, tachycardia, nasal stuffiness and postural