Enalapril maleate

Description

Enalapril maleate is the second angiotensin converting enzyme inhibitor to reach the marketplace. Like captopril, the first entry in this area, enalapril is useful in the treatment of hypertension and congestive heart failure. It has a longer effective half-life than captopril, allowing once or twice-daily dosing, and appears to have a somewhat lower incidence of side effects.

Chemical properties

White to Off-White Crystalline Powder

Originator

Merck (USA)

The Uses of Enalapril maleate

Enalapril maleate salt is used as a long-acting ACE inhibitor and antihypertensive, used to study diabetic angiopathy in diabetic rats and inhibition of ACE in hog plasma (I50=1.2nM). ACE inhibitors disturb the enin-angiotensin- aldosterone system. Additional ACE inhibitors include: Enalapril, Enalaprilat dihydrate, Enalaprilat, and Enalapril-d5 Maleate Salt, among others.

The Uses of Enalapril maleate

An antihypertensive. An angiotensin-converting enzyme (ACE) inhibitor.

The Uses of Enalapril maleate

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What are the applications of Application

Enalapril Maleate is an angiotensin-converting enzyme inhibitor

Definition

ChEBI: The maleic acid salt of enalapril. It contains one molecule of maleic acid for each molecule of enalapril. Following oral administration, the ethyl ester group of enalapril is hydrolysed to afford the corresponding carboxylic acid, enalaprilat, an angioten in-converting enzyme (ACE) inhibitor. Enalapril is thus a prodrug for enalaprilat (which, unlike enalapril, is not absorbed by mouth), and its maleate is used in the treatment of hypertension and heart failure, for reduction of proteinuria and renal diseas in patients with nephropathies, and for the prevention of stroke, myocardial infarction, and cardiac death in high-risk patients.

Manufacturing Process

N-[1(S)-Ethoxycarbonyl-3-phenylpropyl]-L-alanyl-L-proline maleic acid salt
A mixture of 3 g of L-alanyl-L-proline, 5 g of ethyl 2-oxo-4-phenyl-butanoate, 13 g of 3A molecular sieves, and 3.6 g of Raney nickel in 85 ml of ethanol is hydrogenated at 25°C and at 40 psig of hydrogen until uptake of hydrogen ceases. The solids are filtered, washed with 80 ml of ethanol and the filtrates are combined. Assay by high pressure liquid chromatography shows an 87:13 ratio of diastereoisomers in favor of the desired product. Ethanol is removed under vacuum to afford an oil which is dissolved in 60 ml of water and 20 ml of ethyl acetate. The pH of the stirred two-phase mixture is adjusted to 8.6 with 50% NaOH. The layers are separated and the water phase is extracted with 2x20 ml of ethyl acetate. The water phase is adjusted to pH 4.25 with hydrochloric acid, 12 g of NaCl is dissolved in the water, and product is extracted with 5x12 ml of ethyl acetate. The extracts are combined and dried with Na2SO4. The desired product, N-[1-(S)-ethoxycarbonyl-3-phenylpropyl]- L-alanyl-L-proline, is crystallized as its maleate salt by addition of 1.86 g of maleic acid. After stirring for 4 hours, the salt is filtered, washed with ethyl acetate and dried to afford 5.2 g of pure product, melting point 150°-151°C.

brand name

RENITEN

Therapeutic Function

Antihypertensive

General Description

Enalapril maleate, 1-[N[(S)-1-carboxy-3-phenylpropyl]-L-alanyl]-L-proline 1 -ethyl estermaleate (Vasotec), is a long-acting ACE inhibitor. It requiresactivation by hydrolysis of its ethyl ester to form thediacid enalaprilat. Enalapril is devoid of the side effects ofrash and loss of taste seen with captopril. These side effectsare similar to those of the mercapto-containing drugpenicillamine. The absence of the thiol group in enalaprilmaleate may free it from these side effects. The half-life is11 hours.

Biochem/physiol Actions

A long-acting angiotensin-converting enzyme inhibitor.

Clinical Use

Angiotensin converting enzyme inhibitor:
Hypertension
Heart failure

Veterinary Drugs and Treatments

The principle use of enalapril/enalaprilat in veterinary medicine at present is as a vasodilator in the treatment of heart failure. Recent studies have demonstrated that enalapril, particularly when used in conjunction with furosemide, does improve the quality of life in dogs with heart failure. It is not clear, however, whether it has any significant effect on survival times. It may also be of benefit in treating the effects associated with valvular heart disease (mitral regurgitation) and left to right shunts. It is being explored as adjunctive treatment in chronic renal failure and protein losing nephropathies.
While ACE inhibitors are a mainstay for treating hypertension in humans, they have not been particularly useful in treating hypertension in dogs or cats.

Drug interactions

Potentially hazardous interactions with other drugs
Anaesthetics: enhanced hypotensive effect.
Analgesics: antagonism of hypotensive effect and increased risk of renal impairment with NSAIDs; hyperkalaemia with ketorolac and other NSAIDs
Antihypertensives: increased risk of hyperkalaemia, hypotension and renal failure with ARBs and aliskiren.
Bee venom extract: possible severe anaphylactoid reactions when used together
Ciclosporin: increased risk of hyperkalaemia and nephrotoxicity.
Cytotoxics: increased risk of angioedema with everolimus.
Diuretics: enhanced hypotensive effect;hyperkalaemia with potassium-sparing diuretics
ESAs: increased risk of hyperkalaemia; antagonism of hypotensive effect.
Gold: flushing and hypotension with sodium aurothiomalate.
Lithium: reduced excretion, possibility of enhanced lithium toxicity.
Potassium salts: increased risk of hyperkalaemia
Tacrolimus: increased risk of hyperkalaemia and nephrotoxicity.

Metabolism

Following absorption, oral enalapril is rapidly and extensively hydrolysed to enalaprilat, a potent angiotensin converting enzyme inhibitor. Peak serum concentrations of enalaprilat occur about 4 hours after an oral dose of enalapril tablet, and the effective half-life is 11 hours. Excretion of enalaprilat is primarily renal. The principal components in urine are enalaprilat, accounting for about 40% of the dose, and intact enalapril.