First-dose effects of enalapril and atenolol upon blood pressure and cerebral blood flow in patients with mild hypertension on diuretic therapy.
The present single-blind, randomised, cross-over, placebo-controlled study was set up to compare the first-dose effects upon blood pressure (BP) and cerebral blood flow (CBF, measured by Xenon inhalation) of a single oral dose of atenolol 50 mg and enalapril 5 mg in ten hypertensive patients receiving a thiazide diuretic. It was found that a) the timing and degree of fall in BP after the first dose of atenolol and enalapril on a diuretic background were similar and generally not associated with symptoms or a fall in CBF, and b) dizziness, which is sometimes associated with the first-dose effect of ACE inhibitors in hypertensives on diuretics, can occasionally occur accompanied by a substantial fall (43%) in CBF in the absence of marked falls in systolic blood pressure. It is suggested that the latter event may be linked to a disturbance of cerebral autoregulation in part dependent on localised renin-angiotensin systems.
Kamlow
F
F
Regional Cardiothoracic Department, Brook General Hospital, Woolwich, London.
Cruickshank
J M
JM
Neil-Dwyer
G
G
Dorrance
D E
DE
Hayes
Y
Y
Patel
S
S
Wainwright
R J
RJ
D000368:Aged; D001262:Atenolol / Q000008:administration & dosage / Q000494:pharmacology*; D001581:Benzothiadiazines; D001794:Blood Pressure / Q000187:drug effects*; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004232:Diuretics; D004656:Enalapril / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic; D012083:Renin / Q000502:physiology; D016037:Single-Blind Method; D049993:Sodium Chloride Symporter Inhibitors / Q000627:therapeutic use*; D013997:Time Factors; D014978:Xenon
D001581:Benzothiadiazines; D004232:Diuretics; D049993:Sodium Chloride Symporter Inhibitors; D014978:Xenon; D001262:Atenolol; D004656:Enalapril; D012083:Renin