Effects of an ACE inhibitor or angiotensin receptor blocker on potassium in CAPD patients

Background: Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) have shown numerous benefits to the cardiovascular system. However, using both drugs is associated with hyperkalemia, especially in end-stage renal disease (ESRD) patients. To the authors' knowledge, there has been no prospective systematic study of the safety and potassium homeostasis of both drugs in continuous ambulatory peritoneal dialysis (CAPD) patients. Methods: Twenty-nine stable, normokalemic CAPD patients without potassium-interference drugs were selected randomly to receive, for 4-week periods, 8 mg candesartan or 10 mg enalapril daily. After completion of the initial drug, both treatment groups were crossed. Results: Twenty-one patients completed the study. Baseline blood pressure, serum potassium level, plasma aldosterone, adequacy of dialysis, and residual renal function were not different between both groups. For the total group, serum potassium changes were not significantly different between baseline and at 4 weeks after treatment in both groups. The incidence of hyperkalemia (potassium ≥5.5 mEq/L [mmol/L]) was 13% and not different between groups. Nine of 11 events of hyperkalemia were associated with Kt/V _urea less than 2, and 8 of 11 had low or low-average peritoneal equilibrium tests. Conclusion: In ESRD patients on CAPD, the standard dose of ACE inhibitor, enalapril, or ARB, candesartan,has little effect on serum potassium, despite drops of plasma aldosterone observed. Both drugs should be considered in CAPD patients with hypertension or cardiovascular complications. However, use of both drugs requires caution in patients with inadequate dialysis or low solute transporters, and dietary noncompliant patients as well.