Therapeutic use:The side effects of these AHDs restrict their use in outpatient treatment.They are effective for difficult to control BP. Hydralazine肼苯哒嚎dilates arteries and arterioles..It is used together with a diuretic and a B-blocker.for treatment of moderately severe hypertension Single-use causes reflex tachycardia and sodium retention. Minoxidil咪诺地尔is also used together with a diuretic and a B-blocker,.for treatment of severe or malignant hypertension. Diazoxide is used (i.v.)for treating hypertensive emergency.A B-blocker is used together to minimize reflex activation of the heart. Sodium nitroprusside is another drug for hypertensive emergency.It dilates both arteries and veins.Effect takes place immediately (i.v.)but does not last long(1-2 minutes).Thus continuous infusion is required. Adverse effects and toxicity: Reflex tachycardia,sodium retention,and for nitroprusside,cyanide ion production. Minoxidil causes excessive growth of body hair(hypertrichosis)if used for more than 4 weeks.This effect has been used for treating male pattern baldness(Rogaine). Reflex stimulation in response to VASODILATING DRUGS vasodilating agents PVR ↓Arterial Baroreceptor ↓Natriuresis ↑Sympathetic nervous pressure system outflow ↑Aldosterone ↑Renin release 个PVR 个Heart rate ↓Venous cardiac contractility capacitance ↑ATI ↑Naretension ↑Arterial &plasma volume 个Cardiac output pressure 1616 Therapeutic use: The side effects of these AHDs restrict their use in outpatient treatment. They are effective for difficult to control BP. Hydralazine 肼苯哒嗪 dilates arteries and arterioles. It is used together with a diuretic and a β-blocker, for treatment of moderately severe hypertension. Single-use causes reflex tachycardia and sodium retention. Minoxidil 咪诺地尔 is also used together with a diuretic and a β-blocker, for treatment of severe or malignant hypertension. Diazoxide 二氮嗪 is used (i.v.) for treating hypertensive emergency. A β-blocker is used together to minimize reflex activation of the heart. Sodium nitroprusside 硝普钠 is another drug for hypertensive emergency. It dilates both arteries and veins. Effect takes place immediately (i.v.) but does not last long (1-2 minutes). Thus continuous infusion is required. Adverse effects and toxicity: • Reflex tachycardia, sodium retention, and for nitroprusside, cyanide ion production. • Minoxidil causes excessive growth of body hair (hypertrichosis) if used for more than 4 weeks. This effect has been used for treating male pattern baldness (Rogaine®). VASODILATING DRUGS ↓ PVR ↓ Arterial pressure ↑ Sympathetic nervous system outflow Baroreceptor ↑ Heart rate, cardiac contractility ↓ Venous capacitance ↑ Cardiac output ↑ PVR ↑ Renin release ↑ AT-II ↑ Arterial pressure ↑ Aldosterone ↓ Natriuresis ↑ Na+ retension & plasma volume Reflex stimulation in response to vasodilating agents