Excessive hypotensive response is potentially dangerous, possibly leading to ischemic complications such as stroke, myocardial infarction or blindness in some cases. Thus, in patients who are severely hypertensive but asymptomatic, slower reductions in blood pressure should be provided with oral agents
Labetalol should generally be avoided in patients with asthma, chronic obstructive lung disease, heart failure, bradycardia, or greater than first-degree heart block. In addition, labetalol should not be used without prior adequate alpha-blockade in patients with hyper adrenergic states, such as pheochromocytoma and methamphetamine overdose, since unopposed, inadequately blocked alpha-adrenergic activity can lead to a further rise in blood pressure if beta blockade is not complete
Hydralazine is a direct arteriolar vasodilator with little or no effect on the venous circulation. Thus, precautions are needed in patients with underlying coronary disease or an aortic dissection, and a beta-blocker should be given concurrently to minimize reflex sympathetic stimulation.