A Comparison of Hypotensive Responses After Oral and Intravenous Administration of Enalapril and Lisinopril in Chronic Heart Failure

The acute hypotensive response to oral and parenteral enalapril (E) and lisinopril (LI) was assessed in 24 patients with chronic congestive heart failure in two open, randomized, balanced, crossover studies. In the E study, 12 patients received each of three treatmentsa single oral dose of 10 mg E, a single intravenous bolus of 5 mg E, and a single intravenous bolus of 5 mg enalaprilat (ET). In the LI study, 12 patients received each of two treatmentsa single oral dose of 10 mg LI and a single intravenous bolus of 5 mg LI. Intraarterial blood pressure was measured continuously. Significant decreases from baseline in mean arterial pressure (MAP) were observed in all cases, starting at 15 min. The maximal hypotensive effect (MAP; mean ± SD) was greatest and the nadir earliest for intravenous ET (– 30 ± 7 mm Hg at 75 min) compared with oral E (– 25 ± 10 mm Hg at 210 min) and intravenous E (– 19 ± 10 mm Hg at 195 min). Oral E and intravenous E had similar onsets of action. The maximal reduction following oral LI (– 19 ± 13 mm Hg at 210 min) was similar to oral E and intravenous E. The effect of intravenous LI ( −25 ± 9 mm Hg at 105 min) was similar to that of intravenous ET. Among the parenteral treatments, E produced the most gradual and least pronounced reduction in blood pressure, and may be best suited for use in the acute situation to minimize the risk of abrupt hypotension. All treatments were well tolerated, except for one patient who received an angiotensin II infusion because of symptomatic hypotension following parenteral ET.