Effects of a low-sodium high-potassium salt in hypertensive patients treated with metoprolol: a multicentre study.

A multicentre study, involving 358 subjects, was carried out to evaluate the effects of a low-Na/high-K dietary salt in hypertensive patients receiving beta-blocker monotherapy. At the end of a 4-week treatment period with 200 mg slow-release metoprolol patients were randomly divided into two groups: one group was given common salt and the other the dietary salt. Both salts were given at table, in double-blind conditions over a period of 4 weeks. The dietary salt group showed a systolic and diastolic blood pressure (BP) reduction (4.2 and 3.0 mmHg, respectively, in the supine position and 4.0 and 2.5 mmHg in the standing position), which was virtually absent in the common salt group. A statistically significant difference between the two groups was found only between the systolic values (P less than 0.05). Twenty-four-hour urinary sodium excretion did not change in either group, while the excretion of 24-h urinary potassium increased significantly in the dietary salt group. It is concluded that in mild or moderately hypertensive patients already receiving a beta-blocker, ancillary treatment with a low-Na/high-K salt can be expected to lead to a further, slight reduction in systolic BP, probably due to the daily potassium load (around 20 mmol).