BLOOD-PRESSURE AND METABOLIC RESPONSES TO MODERATE SODIUM RESTRICTIONIN ISRADIPINE-TREATED HYPERTENSIVE PATIENTS

This multicenter, randomized, controlled clinical trial assessed the i nfluence of sodium chloride intake on the antihypertensive effect of t he calcium channel blocker isradipine. Participants with uncomplicated hypertension controlled by isradipine entered a 4-week sodium-restric ted (60 to 80 mmol/24 h) period. Participants with urinary sodium leve ls <120 mmo1/24 h (n = 99) were randomized to placebo or sodium chlori de (100 mmo1/24 h) for 4 weeks, and then crossed over to the alternati ve treatment for an additional 4 weeks. Mean baseline systolic blood p ressure was 151.9 +/- 16.7 mm Hg (mean +/- SD). During open-label isra dipine treatment, systolic blood pressures for ad libitum sodium chlor ide and restriction were 134.1 +/- 11.1 and 132.1 +/- 12.2 mm Hg respe ctively; for double-blind sodium chloride restriction and supplementat ion: 133.6 +/- 12.6 and 138.5 +/- 12.8 mm Hg (P < .01). Urinary sodium excretion values for open-label isradipine ad libitum versus restrict ed were 140.6 +/- 61.9 versus 76.9 +/- 32.4 mmo1/24 h; for double-blin d restricted versus supplemented, sodium excretion was 120.5 +/- 68.9 v 175.9 +/- 68.7 mmol/24 h (P less than or equal to .0001). Changes in urinary sodium excretion were not predictive of variations in blood p ressure. Urinary sodium excretion during sodium restriction correlated directly with HDL-cholesterol (P < .02) and inversely with total chol esterol:HDL-cholesterol (P = .02), despite decreased total and saturat ed fat intake (P < .01). Sodium restriction was associated with signif icant reductions (P < .01) in virtually all macronutrients and electro lytes, and thus had an adverse impact on overall nutrition. The antihy pertensive action of isradipine was not enhanced by dietary sodium chl oride restriction, and the lipoprotein profile was least favorable wit h sodium chloride restriction. (C) 1997 American Journal of Hypertensi on, Ltd.