Enalapril in the Management of Hypertension Associated With Renal Artery Stenosis

Enalapril maleate (MK-421) is a new non-sulfhydryl-containing converting-enzyme inhibitor that has been shown to be effective and well tolerated in patients with essential hypertension. Data on its effectiveness and safety in patients with renovascular hypertension are limited and have involved predominantly short-term observations. This is particularly true with respect to the long-term effects of enalapril on renal function. We report our experience using the combination of enalapril and hydrochlorothiazide (HCTZ) in a group of nine patients with moderate to severe hypertension associated with renal artery stenosis. The enalapril-HCTZ combination successfully controlled blood pressure in seven patients during a six-week period of study. Adverse effects were not noted, and detailed renal hemodynamic studies did not reveal any significant changes of renal plasma flow and glomerular filtration rate during this time interval. Five patients were continued on this regimen for a period of six to 18 months. In this group of patients, the regimen continued to be well tolerated and to provide excellent blood pressure control: glomerular filtration rate was maintained in two patients and variable grades of decrease were noted in three. The mechanism of this delayed renal dysfunction as well as its relationship to enalapril treatment remain unclear. The long-term impact of converting-enzyme inhibition on renal function requires further study.