A selection of resources
For true hypertensive emergencies the european society of cardiology(recommendation 8.3) has had handy table on the onset and duration of the intravenous medications. However, if there is no signs of end-organ damage they do not recommend inpatient treatment but urgent outpatient review.
NICE guidelines recommend same day treatment only if “new onset confusion, chest pain, signs of heart failure, or acute kidney injury” or if signs of end organ damage (recommend ecg, u/e, urine dip and fundoscopy.” However still only recommends oral treatment in these patients.
Whilst there seems no decent randomised controlled trials on asymptomatic hypertension there is a few studies on when/ how much to lower blood pressure in the various true hypertensive emergencies.