Antihypertensive activity of verapamil: impact of dietary sodium. The VERSAL Study Group

To define the influence of dietary salt intake on the antihypertensive effect of slow-release verapamil 240 mg once a day in a population with mild-to-moderate essential hypertension.

Parallel, randomized, multicentre study.

Patients were advised to follow a moderately low salt diet (Low-salt group). After a 2-week run-in period, those patients with 24-h urinary sodium excretion (UNa) < or = 120 mmol/day and a diastolic blood pressure (DBP) between 90 and 114 mmHg were randomly assigned to verapamil + Low-salt or verapamil + unrestricted-salt diet (High-salt group) for 28 days. Compliance with diets was defined as Low-salt UNa < or = 120 mmol/day and High-salt UNa > 120 mmol/day with UNa increased by > or = 60 mmol/day over the level attained at the end of the run-in period.

Significant reductions in mean systolic blood pressure (SBP) and DBP were found in both the Low-salt (n = 235) and High-salt (n = 183) groups. The therapeutic goal (DBP < 90 mmHg) was achieved in 38.3% of patients in the Low-salt and 44.8% of patients in the High-salt group. Office blood pressure results were confirmed by ambulatory 24-h blood pressure monitoring in a subsample of patients. Verapamil reduced mean blood pressure throughout the nycthemeral cycle without any significant difference between the two groups.

The restriction in sodium intake does not have an additive effect on the antihypertensive effect of the slow-channel calcium antagonist verapamil.