Salt and blood pressure responses to calcium antagonism in hypertensive patients.
Since salt intake may affect blood pressure response to antihypertensive drugs, an individual's salt-sensitivity status may be an important consideration in the selection of a medication. The purpose of this single-blind study was to assess the impact of salt sensitivity on the antihypertensive effects of isradipine. A total of 21 evaluable hypertensive patients (10 white, 11 black) 35 to 73 years of age (mean 55.9 years) were randomized to a low-salt diet (mean 24-hour urine sodium 100+/-14 mmol) or a high-salt diet (mean 24-hour urine sodium 210+/-22 mmol) for 7 weeks, followed by crossover to the other diet after a 2-week washout period. On each diet regimen, patients received placebo for 2 weeks, followed by optimal titration of isradipine (2.5 to 10 mg BID) for blood pressure control during the last 5 weeks. On the high-salt diet, salt-sensitive hypertensives (mean arterial blood pressure increase > or = 5 mm Hg, n=5) exhibited a systolic/diastolic blood pressure change of -18.7/-19.6 mm Hg from 157.2/102.9 mm Hg after 5 weeks of isradipine treatment, whereas on a low-salt diet, blood pressure change was -6.9/-12.0 mm Hg from 148.7/97.3 mm Hg. Non-salt-sensitive patients (n=16) exhibited a systolic/diastolic blood pressure change of -12.6/-7.6 mm Hg from 155.3/98.6 mm Hg on the high-salt diet and -19.2/-10.9 mm Hg from 161.0/102.6 mm Hg on the low-salt diet after treatment with isradipine. The absolute blood pressure attained in both salt-sensitive and non-salt-sensitive patients was almost identical with isradipine therapy despite variation in dietary salt, although slightly higher doses of isradipine were required in the salt-sensitive group. Consequently, isradipine, and perhaps calcium antagonists in general, manifests a more robust blood pressure-lowering effect in the setting of high sodium intake. This effect does, however, appear to be largely confined to individuals who are salt sensitive.
Weir
M R
MR
Department of Medicine, University of Maryland School of Medicine, Baltimore 21201-1595, USA. mweir@ummpa.ab.umd.edu
Hall
P S
PS
Behrens
M T
MT
Flack
J M
JM
D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D018592:Cross-Over Studies; D004039:Diet, Sodium-Restricted; D004351:Drug Resistance; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D017275:Isradipine / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D016037:Single-Blind Method; D012965:Sodium Chloride / Q000494:pharmacology*
D000959:Antihypertensive Agents; D002121:Calcium Channel Blockers; D012965:Sodium Chloride; D017275:Isradipine