Inhibition of the renin-angiotensin-aldosterone axis by low dose intravenous captopril as a treatment for accelerated phase hypertension.
A parenteral preparation of captopril has been used to produce a smooth reduction of blood pressure in patients presenting with accelerated phase hypertension. In five out of six patients studied, an intravenous infusion of captopril at dose rates ranging from 250-2000 micrograms/h lowered blood pressure from 199 +/- 13/115 +/- 5 to 143 +/- 14/86 +/- 5 mmHg over several hours without adverse effects. Partial inhibition of the angiotensin converting enzyme was demonstrated by a rise in plasma renin activity (PRA) and a fall (although not to normal) in elevated levels of angiotensin II and aldosterone. The plasma level of free captopril at the point of blood pressure control was 15 +/- 4 ng/ml and its short effective half-life was demonstrated by a rise in blood pressure within 15 minutes of stopping the infusion. These data demonstrate that very small amounts of captopril can produce a dose-dependent inhibition of angiotensin converting enzyme without abrupt changes in blood pressure.
Padfield
P L
PL
Department of Medicine, Western General Hospital, Edinburgh, Scotland.
Rademaker
M
M
Atherden
S M
SM
Davies
E
E
Edwards
C R
CR
Eglen
A
A
Williams
B C
BC
D000328:Adult; D002216:Captopril / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D006974:Hypertension, Malignant / Q000188:drug therapy* / Q000503:physiopathology; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D012084:Renin-Angiotensin System / Q000187:drug effects*
D002216:Captopril