A list of AHDs for treatment of hypertensive emergencies (DBP>120 mmHg,potentially life-threatening,seen in pheochromocytoma crisis,eclampsia, cocaine overdose,clonidine withdrawal,etc.) Nitroprusside,IV,rapid action(within seconds),short lasting(a few minutes),requires continuous IV infusion.May cause thiocyanate toxicity.Avoid use in renal failure and pregnancy. Diazoxide,IV,action takes 1-5 min,lasts 4-12 hrs.May cause hyperglycemia,sodium retention,tacycardia.Avoid use in angina pectoris,Ml,pulmonary edema,intracranial hemorrhage. Enalaprilat,IV,action seen in 15 min,max in 1-4 hrs,lasts 6-12 hrs.May cause hyperkalemia.Do not use in pregnancy,renal failure in patients with bilateral renal artery stenosis. Hydralazine,IV(action in 10-30 min)or IM(action in 20-40 min),lasts 2-6 hrs.May cause angina,tachycardia,headache.Do not use in angina pectoris,MI,aortic dissection. Others:Labetalol,nicardipine,nitroglycerin,trimethaphan,phentolamine. Calcium channel blockers(CCBs) Considered as a different class of vasodilators that are used in treatment of angina and hypertension. Mechanism of action is based on the role of calcium in maintaining smooth muscle tone and in the contraction of myocardium.Blocking the entry of calcium through cell surface L-type channels relaxes smooth muscle cells.Selective blocks arteriole smooth muscle cells is most desirable for reduction of PVR. There are dihydropyridine CCBs and non-dihydropyridine CCBs in treating hypertension.These are alternative drugs for initial treatment of hypertension in patients who cannot take B-blockers(e.g.due to angina bronchospastic disease). Diphenylalkylamines-Verapamil:维拉帕米，is less selective on the type of calcium channels and have effects on both arteriole and cardiac SMC. Benzothiazepines-Diltiazem地尔镰卓，has similar function but less adverse effect than verapamil 1717 A list of AHDs for treatment of hypertensive emergencies (DBP > 120 mmHg, potentially life-threatening, seen in pheochromocytoma crisis, eclampsia, cocaine overdose, clonidine withdrawal, etc.) Nitroprusside, IV, rapid action (within seconds), short lasting (a few minutes), requires continuous IV infusion. May cause thiocyanate toxicity. Avoid use in renal failure and pregnancy. Diazoxide, IV, action takes 1-5 min, lasts 4-12 hrs. May cause hyperglycemia, sodium retention, tacycardia. Avoid use in angina pectoris, MI, pulmonary edema, intracranial hemorrhage. Enalaprilat, IV, action seen in 15 min, max in 1-4 hrs, lasts 6-12 hrs. May cause hyperkalemia. Do not use in pregnancy, renal failure in patients with bilateral renal artery stenosis. Hydralazine, IV (action in 10-30 min) or IM (action in 20-40 min), lasts 2-6 hrs. May cause angina, tachycardia, headache. Do not use in angina pectoris, MI, aortic dissection. Others: Labetalol, nicardipine, nitroglycerin, trimethaphan, phentolamine. Calcium channel blockers (CCBs) • Considered as a different class of vasodilators that are used in treatment of angina and hypertension. • Mechanism of action is based on the role of calcium in maintaining smooth muscle tone and in the contraction of myocardium. Blocking the entry of calcium through cell surface L-type channels relaxes smooth muscle cells. Selective blocks arteriole smooth muscle cells is most desirable for reduction of PVR. • There are dihydropyridine CCBs and non-dihydropyridine CCBs in treating hypertension. These are alternative drugs for initial treatment of hypertension in patients who cannot take β-blockers (e.g. due to angina + bronchospastic disease). Diphenylalkylamines – Verapamil 维拉帕米, is less selective on the type of calcium channels and have effects on both arteriole and cardiac SMC. Benzothiazepines – Diltiazem 地尔硫卓, has similar function but less adverse effect than verapamil