I have few questions regarding this drug. So if the order for Labetalol is 10mg if systolic >160 and 20mg if systolic >180 how much mg do you give if BP reads 180/120?? Is there a certain BP range protocol for what dosage to start labetalol with?? And also is 20mg Labetalol huge enough to cause someone go at shock and not recover after. Katzung pharmacology says labetalol reduces BP by lowering systemic vascular resistance without significant alteration in heart rate or cardiac output.