[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.