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哌唑嗪选择性地阻断突触后α_1-肾上腺素能受体,通过减少周围血管阻力而降低血压。其它α-阻滞剂如酚妥拉明和苯氧苄胺则同时阻断α_1和α_2(突触前受体),升高血浆去甲肾上腺素浓度,增加肾素释放,引起心动过速,从而阻碍了其在临床上用于治疗高血压。直接作用的血管扩张剂如肼苯哒嗪、敏乐啶、氯苯甲噻二嗪与硝普钠也有这些反应,虽然其程度较轻。哌唑嗪相对地没有这些影响,而且,由于其作用不经过中枢神经系统,所以罕见嗜睡、抑郁与幻觉。
Prazosin selectively blocks the postsynaptic [alpha] 1 -adrenoceptor and lowers blood pressure by reducing peripheral vascular resistance. Other alpha-blockers, such as phentolamine and phenoxybenzylamine, block both alpha 1 and alpha 2 (presynaptic receptors), increase plasma norepinephrine concentrations, increase renin release, and cause tachycardia, thereby Hinder its clinical use for the treatment of hypertension. Directly acting vasodilators such as hydralazine, minoxidil, chlorbenzothiadiazine and sodium nitroprusside also have these reactions, albeit to a lesser extent. Prazosin relatively does not have these effects, and, because its effect does not pass through the central nervous system, rare lethargy, depression and hallucinations.