[Hyperkalemia in hypertensive patients undergoing regular hemodialysis during enalapril and fosinopril therapy].

INTRODUCTION Hypertension is evident in 80%-85% of patients with chronic renal failure and antihypertensive therapy is needed in 25%-30% of patients. Apart from antihypertensive effect, ACEi's decrease the left ventricular hypertrophy and mortality in dialysis patients. Even so, their use is limited due to hyperkalemia. OBJECTIVE The objective of the study was to compare the effect of fosinopril and enalapril on serum potassium level in hypertensive hemodialysis patients. METHOD Prospective pilot study included 16 patients undergoing chronic hemodialysis, with mean age of 58.9 +/- 9.6 years and mean duration of hypertension 11.3 +/- 7.1 years. The effect of antihypertensive drugs of equivalent dose was followed during three periods (three months each): period 1 (therapy with enalapril), period 2 (therapy with fosinopril) and period 3 (therapy with enalapril). Dialysis conditions were constant and patients were without signs of catabolic state. Laboratory results were followed on monthly basis and mean values were compared by ANOVA-one way test. Difference between variables between periods was tested using Bonferoni method. RESULTS There was significant difference between mean serum potassium levels throughout three therapeutic periods (5.88 +/- 0.38 vs. 4.9910.44 vs. 5.46 +/- 0.46mmol/l; p<0.001). Difference was evident even in the first month of fosinopril therapy. The effect can not be explained by dialysis adequacy since Kt/ V was similar throughout three treatment periods (1.18 +/- 0.24 vs. 1.25 +/- 0.21 vs. 1.25 +/- 0.14; p=ns). Systolic blood pressure was regulated even better with fosinopril than with enalapril (187.5 +/- 21.4 mmHg vs. 160.0 +/- 20.0 mmHg; p=0.01) and this effect was prolonged during period 3 (160.0 +/- 26.1mmHg). Hemoglobin values mainly depended on specific anemia therapy and not on particular ACEi drug. CONCLUSION Fosinopril carries less risk of hyperkalemia in hypertensive hemodialysis patients than enalapril. Although definite conclusion may be drawn after well-designed studies, the results presented in this pilot study suggest that fosinopril may be recommended for hypertensive hemodialysis patients who are at risk to develop inter-dialytic hyperkalemia.