RAMIPRIL DECREASES CHLORTHALIDONE-INDUCED LOSS OF MAGNESIUM AND POTASSIUM IN HYPERTENSIVE PATIENTS

A double-blind clinical trial was conducted to compare the efficacy of and electrolyte changes caused by ramipril-chlorrhalidone combination treatment (5 mg +/- 25 mg) and chlorthalidone monotherapy (25 mg dail y) in patients with hypertension. After a l-week placebo period, 32 pa tients (mean age, 51 +/- 9 years) with essential hypertension (average blood pressure of 181.4/104.5 +/- 13.0/6.9 mmHg) were randomly assign ed to receive combination therapy (group A, n = 17) or monotherapy (gr oup B, n = 15). After 12 weeks of active treatment, systolic and diast olic blood pressure decreased by 16.1% and 13%, respectively, for pati ents taking combined therapy, and by 12.7% and 9.8%, respectively, for patients taking monotherapy. The difference was significant for betwe en-group comparisons. There were no changes in serum sodium concentrat ion, but a significant similar increase in 24-hour urinary sodium excr etion was seen in both groups. Serum calcium levels increased slightly and 24-hour urinary calcium excretion decreased significantly in both groups, probably due to chlorthalidone administration. Serum potassiu m levels increased slightly in group A (from 4.16 +/- 0.39 mmol/L to 4 .30 +/- 0.42 mmol/L) and decreased slightly in group B (from 4.18 +/- 0.32 mmol/L to 3.99 +/- 0.49 mmol/L). Urinary potassium excretion did not change significantly in group A, but increased by similar to 15% i n group B. There runs a decrease in 24-hour urinary magnesium excretio n (from 4.01 +/- 1.24 mmol/24 hours to 3.50 +/- 0.93 mmol/24 hours) in group A and an increase (from 3.49 +/- 0.98 mmol/24 hours to 4.35 +/- 1.12 mmol/24 hours) in group B. At the end of the trial these changes were significant in between-group comparisons. Consistent with the pr eviously shown amelioration by ramipril of thiazide-induced metabolic side-effects, ramipril appears to improve magnesium balance during cot reatment with chlorthalidone.