Crossover comparison of the effects of enalapril and captopril on potassium homeostasis in patients with mild hypertension.
The effects of two types of angiotensin converting enzyme (ACE) inhibitors, enalapril (long-acting) and captopril (short-acting), on serum electrolytes and circadian rhythm of urinary electrolyte excretions were compared in relation to aldosterone status in patients with essential hypertension and normal renal function. Enalapril (5 mg once daily) and captopril (12.5 mg t.i.d.) were administered to 11 patients for 1 week each in a crossover fashion. Blood sampling in the early morning and 4-hour split urinary sampling for 24 hours were performed on the last day of control and each treatment periods. Enalapril and captopril significantly reduced blood pressure to similar levels. Enalapril but not captopril significantly inhibited plasma aldosterone concentration and urinary aldosterone excretion. Neither drug apparently altered serum or urinary Na levels. Both drugs significantly decreased urinary K excretion (p < 0.05, control: 44 +/- 4 mEq/day, captopril: 39 +/- 2 mEq/day, enalapril: 39 +/- 2 mEq/day; mean +/- SEM), but did not significantly alter serum K level (control: 4.1 +/- 0.1 mEq/l, captopril 4.2 +/- 0.2 mEq/l, enalapril 4.3 +/- 0.1 mEq/l). The circadian rhythm (acrophase) of urinary K excretion was not affected by either drug, while the amplitude was decreased by both, as assessed by the cosinor method. In summary, although enalapril caused more sustained inhibition of aldosterone secretion compared with captopril, both drugs showed similar effects on the K homeostasis in patients with mild essential hypertension.
Ohya
Y
Y
Second Department of Internal Medicine, Kyushu University, Faculty of Medicine, Fukuoka, Japan.
Ueno
M
M
Takata
Y
Y
Tominaga
M
M
Ohmori
S
S
Kobayashi
K
K
Abe
I
I
Fujishima
M
M
D000450:Aldosterone / Q000378:metabolism; D001794:Blood Pressure / Q000187:drug effects; D002216:Captopril / Q000494:pharmacology*; D002940:Circadian Rhythm; D018592:Cross-Over Studies; D004334:Drug Administration Schedule; D004656:Enalapril / Q000494:pharmacology*; D005260:Female; D006706:Homeostasis / Q000187:drug effects*; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000378:metabolism / Q000652:urine; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000378:metabolism* / Q000652:urine; D012964:Sodium / Q000378:metabolism / Q000652:urine
D000450:Aldosterone; D004656:Enalapril; D002216:Captopril; D012964:Sodium; D011188:Potassium