Enalapril (maleate)

Enalapril maleate (MK-421 maleate) is an orally active angiotensin-converting enzyme inhibitor. Enalapril maleate blocks the conversion of angiotensin I to angiotensin II, regulates the renin-angiotensin system, reduces preload and afterload, and decreases plasma angiotensin II levels. Enalapril maleate inhibits apoptosis, reduces nitric oxide metabolite levels, stabilizes endothelial cells, enhances endothelial antioxidant defense, scavenges reactive oxygen species (ROS), and alleviates neuronal damage. Enalapril maleate attenuates glutathione depletion, protein/lipid oxidation, tissue damage, and type III collagen immunolabeling in organs of diabetic rats. Enalapril maleate reduces systolic blood pressure and urinary albumin excretion, and delays the progression of diabetic cardiac/renal injury. Enalapril maleate is used in research related to asymptomatic left ventricular dysfunction, congestive heart failure, Alzheimer's disease, diabetes mellitus, acute myocardial infarction, atrial fibrillation, hypertension, cerebral ischemia, chronic heart failure, and single-ventricle physiology^{[1][2][3][4][5][6][7][8][9][10]}. In Vitro:Pretreatment with Enalapril (50 µM; 24 h) maleate significantly reduces AD serum-induced apoptosis in HUVECs, whereas post-treatment with the same concentration and duration does not provide this protective effect^[3].
Enalapril (0.1-100.0 μM; 24 h) maleate dose-dependently inhibits staurosporine-induced apoptosis in primary chick embryo telencephalon neurons, with significant reductions in apoptotic neuron percentages observed at all tested concentrations^[8].
Both pretreatment and post-treatment with Enalapril (50 µM; 24 h) maleate significantly reduces elevated nitrite levels in HUVEC culture supernatants induced by exposure to AD patient sera^[3].
Enalapril maleate when incorporated with 10-20% (w/w) stearic acid into microcrystalline cellulose pellets as Enalapril maleate significantly improves Enalapril maleate stability under accelerated 40°C/75% RH conditions for 91 days, reducing formation of the degradation products Enalapril maleateate and diketopiperazine more effectively than conventional Enalapril maleate or Enalapril sodium salt pellets, while stearic acid destabilizes Enalapril maleate when combined with Enalapril maleate sodium salt in pellets^[7].
Enalapril maleate as Enalapril maleate shows no significant interaction with stearic acid in 1:1 (w/w) binary mixtures, but as Enalapril sodium salt interacts with stearic acid to reduce its thermal stability, lowering the onset temperature for diketopiperazine formation by ~22°C^[7].
Enalapril maleate when incorporated with 5% (w/w) crospovidone into microcrystalline cellulose pellets containing 10% (w/w) stearic acid enables Enalapril maleate release of 89.51% at 30 min, meeting USP immediate-release criteria^[7].
Enalapril (0.1-100.0 μM; 24 h) maleate dose-dependently protects primary chick embryo telencephalon neurons from glutamate- and Fe²⁺/³⁺-induced damage, with significant reductions in damaged neuron percentages observed at concentrations ≥0.1 μM for glutamate and ≥10.0 μM for Fe²⁺/^3+[8].
Enalapril (0.1-100.0 μM; 3 h (Fe²⁺/³⁺, staurosporine); 1 h (glutamate)) maleate dose-dependently reduces Fe²⁺/³⁺-, glutamate-, and staurosporine-induced mitochondrial reactive oxygen species generation in primary chick embryo telencephalon neurons, with significant reductions observed at concentrations ≥1.0 μM for all treatments^[8]. In Vivo:Enalapril (20 mg/L; p.o.; continuous; 8 months) maleate attenuates oxidative stress and reduces heart, kidney, and liver tissue damage in streptozotocin-induced diabetic rats, including an 86% reduction in heart fibrosis scores^[4].
Enalapril (0.03 mg/kg; i.p.; single dose; 1 hour before permanent middle cerebral artery occlusion) maleate significantly reduces cortical infarct area in male NMRI mice^[8].