Adverse effects of α1-adrenergic blocking drugs

摘要: Earlier nonselective α1-adrenergic blocking drugs such as phentolamine and phenoxybenzamine are now restricted to the pharmacological management of crisis phaeochromocytoma. Prazosin, first selective α1-blocker approved for treatment hypertension, became available in mid-1970s. Additional α1-blockers doxazosin terazosin have been introduced during recent years. The undesirable effects all members this class similar. Most adverse events can be attributed reversible competitive antagonism postsynaptic receptors tissues that sustain high levels α-adrenergic sympathetic tone, e.g. resistance arteries, capacitance veins urinary bladder outflow tract. Orthostatic hypotension with a sensation intense faintness occasional syncope, occur shortly after initial dose. Aggravating factors include upright posture, intravascular volume depletion concurrent administration other medications lower blood pressure, including classes antihypertensive drugs. problem is reduced or avoided by choice low starting doses, beginning at bedtime minimising risks.