There is no RCT evidence demonstrating that antihypertensive drugs reduce mortality or morbidity in patients with hypertensive emergencies .
Furthermore , there is insufficient RCT evidence to determine which drug or drug class is most effective in reducing mortality and morbidity .
There were some minor differences in the degree of blood pressure lowering when one class of antihypertensive drug is compared to another .
However , the clinical significance is unknown .
Hypertensive emergencies occur when high blood pressure is associated with the presence of acute end-organ damage , such as hypertensive encephalopathy .
There is controversy as to when and which antihypertensive drugs to use in these situations .
Emergency treatment of severe hypertension evaluated in a randomized study. Effect of rest and furosemide and a randomized evaluation of chlorpromazine, dihydralazine and diazoxide. Danish Multicenter Study.
. Emergency treatment of  acute , severe hypertension  was monitored prospect ively during a period of nine months in a Danish multicenter trial . A total of 101 patients with supine diastolic blood pressures ( DBP ) , phase V , ≥135 mmHg in three measurements at 5 min intervals entered the study . The emergency treatment was divided into three periods . In period I , lasting for the first hour , the patient was placed in the supine position and no drug treatment was given . If DBP did not fall below 135 mmHg , the patient entered period II , during which furosemide , 80 mg i.v . , was given and observation continued for another hour . Patients with pronounced hypertensive encephalopathy ( n = 15 ) and left venticular heart failure ( n = 2 ) started directly at period II . Provided DBP thereafter was still 135 mmHg or higher , the patients were r and omized in period III ( 2nd-5th hour ) to treatment with either chlorpromazine or dihydralazine in small refractory i.v . doses or diazoxide , 5 mg/kg b.wt . i.v . , as a bolus injection . In period I , DBP fell below our “ emergency limit ” of 135 mmHg in 23 ( 27 % ) of 84 patients whose mean arterial BP fell from 171 to 140 mmHg during the study . In period II , DBP fell below 135 mmHg in 23 ( 30 % ) of 78 patients and their mean arterial BP decreased from 174 to 135 mmHg during the study . In period III , 24 patients were treated with chlorpromazine , 16 with dihydralazine and 15 with diazoxide . In patients treated with chlorpromazine or dihydralazine  , BP decreased gradually during the first hour , on average from 211/146 to 155/103 and from 219/147 to 162/89 mmHg , respectively . After diazoxide BP decreased abruptly in the first two minutes , on average from 211/144 to 166/100 mmHg . The complication rate was generally low and only a few patients were resistant to any of the treatments given . The study was not able to demonstrate that diazoxide is preferable to the other two drugs in emergency treatment
There is no RCT evidence demonstrating that antihypertensive drugs reduce mortality or morbidity in patients with hypertensive emergencies .
Furthermore , there is insufficient RCT evidence to determine which drug or drug class is most effective in reducing mortality and morbidity .
There were some minor differences in the degree of blood pressure lowering when one class of antihypertensive drug is compared to another .
However , the clinical significance is unknown .
Hypertensive emergencies occur when high blood pressure is associated with the presence of acute end-organ damage , such as hypertensive encephalopathy .
There is controversy as to when and which antihypertensive drugs to use in these situations .