Hormonal, Blood Pressure, and Peritoneal Transport Response to Short -Term Ace Inhibition

OBJECTIVES: To evaluate the hormonal, blood pressure, and peritoneal transport effects of intraperitoneal enalaprilat and oral enalapril. DESIGN: A nonrandomized, nonblinded, prospective clinical trial was performed. SETTING: The study was conducted at the Clinical Research Unit at the Medical College of Virginia, a tertiary care center. PATIENTS: Six continuous ambulatory peritoneal dialysis (CAPD) patients with hypertension were enrolled in the study. All 6 patients received intraperitoneal enalaprilat. Five of the patients also received oral enalapril. INTERVENTIONS: Hormonal, clinical, and transport parameters were investigated in patients given intraperitoneal enalaprilat and oral enalapril. Standardized 2-L exchanges were performed during a control period, following 2.5 mg intraperitoneal enalaprilat and after a week of oral enalapril. Inulin, blood urea nitrogen (BUN) and creatinine clearances, and glucose absorption were determined during these exchanges. RESULTS: After intraperitoneal enalaprilat, both systolic and diastolic blood pressure significantly declined, reaching maximal decreases of -21.7 +/- 14.2% at 95 +/- 92 minutes, and of -23.3 +/- 15.4% at 105 +/- 105 minutes, respectively. Plasma angiotensin converting enzyme (ACE) activity was suppressed below detectable limits at four hours following intraperitoneal enalaprilat, and remained suppressed throughout all sampling time points following oral enalapril treatment. There was no significant change in drain volumes, glucose absorption, or BUN, creatinine, or inulin clearances, whether enalaprilat was administered intraperitoneally or enalapril orally. CONCLUSION: This study demonstrates that intraperitoneal administration of enalaprilat is a rapidly effective route of administration of this ACE inhibitor. There were no changes in peritoneal transport characteristics demonstrated.