Antihypertensives: hypertensive emergencies

1. immediate BP reduction to limit new or progressing target organ damage; parenteral therapy to lower BP toward 160/100 in 1-6 hrs; agent of choice is nitroprusside given as a continuous IV infusion

2. Nitroprusside (IV)

2.1. Na+ nitroprusside

2.2. immediate effects, rapid term of effects when d/c; direct acting vasodilator->NO->cyclic GMP and vasodilation

2.3. onset is 30 sec and peak effects in 2 minutes, disappears after 3 days. metabolized by smooth muscle->thiocyanate and NO

2.4. AE: excessive and rapid hypotension; must use special infusion pump and close BP monitoring; toxic accumulation of cyanide, a metabolite esp if renal or long-term administration

3. labetolol IV

3.1. effective with little effect on heart rate and cardiac output

4. nitroglcerin IV

4.1. dilates arterioles and venules as well as coronary vessels; useful for IHD and severe HTN

5. HTN urgencies

5.1. in office or urgent care center: elevated BP w/o new or progressive target organ damage; oral captopril (works gradually); amlodipine