Overview
DESCRIPTION Enalaprilat injection, USP is a sterile aqueous solution for intravenous administration. Enalaprilat is an angiotensin-converting enzyme inhibitor. It is chemically described as (S)-1-[N-(1-carboxy-3-phenylpropyl)-L-alanyl]-L-proline dihydrate. Its molecular formula is C 18 H 24 N 2 O 5 •2H 2 O and its structural formula is: Enalaprilat, USP is a white or almost white crystalline...
Mechanism of Action
CLINICAL PHARMACOLOGY Enalaprilat, an angiotensin-converting enzyme (ACE) inhibitor when administered intravenously, is the active metabolite of the orally administered pro-drug, enalapril maleate. Enalaprilat is poorly absorbed orally. Mechanism of Action Intravenous enalaprilat, or oral enalapril, after hydrolysis to enalaprilat, inhibits ACE in human subjects and animals. ACE is a peptidyl dipeptidase that catalyzes the conversion of angiotensin I to the vasoconstrictor substance, angiotensin II. Angiotensin II also stimulates aldosterone secretion by the adrenal cortex. Inhibition of ACE results in decreased plasma angiotensin II, which leads to decreased vasopressor activity and to decreased aldosterone secretion.
Indications
- INDICATIONS AND USAGE Enalaprilat injection is indicated for the treatment of hypertension when oral therapy is not practical. Enalaprilat injection has been studied with only one other antihypertensive agent, furosemide, which showed approximately additive effects on blood pressure. Enalapril, the pro-drug of enalaprilat, has been used extensively with a variety of other antihypertensive agents, without apparent difficulty except for occasional hypotension.
Common Doses
- 1.25 mg
- 5 mg
- 20 mg
- 0.625 mg
Dosage
DOSAGE AND ADMINISTRATION FOR INTRAVENOUS ADMINISTRATION ONLY The dose in hypertension is 1.25 mg every six hours administered intravenously over a five minute period. A clinical response is usually seen within 15 minutes. Peak effects after the first dose may not occur for up to four hours after dosing. The peak effects of the second and subsequent doses may exceed those of the first. No dosage regimen for enalaprilat injection has been clearly demonstrated to be more effective in treating hypertension than 1.25 mg every six hours.
Black Box Warning
USE IN PREGNANCY When used in pregnancy during the second and third trimesters, ACE inhibitors can cause injury and even death to the developing fetus. When pregnancy is detected, enalaprilat injection should be discontinued as soon as possible. See WARNINGS, Fetal/Neonatal Morbidity and Mortality .
Contraindications
- CONTRAINDICATIONS Enalaprilat injection is contraindicated in patients who are hypersensitive to any component of this product and in patients with a history of angioedema related to previous treatment with an angiotensin-converting enzyme inhibitor and in patients with hereditary or idiopathic angioedema.
Side Effects
- ADVERSE REACTIONS Enalaprilat has been found to be generally well tolerated in controlled clinical trials involving 349 patients (168 with hypertension, 153 with congestive heart failure and 28 with coronary artery disease). The most frequent clinically significant adverse experience was hypotension (3.4 percent), occurring in eight patients (5.2 percent) with congestive heart failure, three (1.8 percent) with hypertension and one with coronary artery disease. Other adverse experiences occurring in greater than one percent of patients were: headache (2.9 percent) and nausea (1.1 percent).
Interactions
- Drug Interactions Hypotension-Patients on Diuretic Therapy : Patients on diuretics and especially those in whom diuretic therapy was recently instituted, may occasionally experience an excessive reduction of blood pressure after initiation of therapy with enalaprilat. The possibility of hypotensive effects with enalaprilat can be minimized by administration of an intravenous infusion of normal saline, discontinuing the diuretic or increasing the salt intake prior to initiation of treatment with enalaprilat.