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Enalapril; Indications/Uses, Dosage, Side Effects, Drug Interaction ,Pregnancy

Enalapril is a dicarbonyl-containing peptide and angiotensin-converting enzyme (ACE) inhibitor with antihypertensive activity. As a prodrug, enalapril is converted by de-esterification into its active form enalaprilat. Enalaprilat competitively binds to and inhibits ACE, thereby blocking the conversion of angiotensin I to angiotensin II. This prevents the potent vasoconstrictive actions of angiotensin II and results in vasodilation. Enalapril also decreases angiotensin II-induced aldosterone secretion by the adrenal cortex, which leads to an increase in sodium excretion and subsequently increases water outflow.

Enalapril is a prodrug that belongs to the angiotensin-converting enzyme (ACE) inhibitor class of medications. It is a potent, competitive inhibitor of ACE, the enzyme responsible for the conversion of angiotensin I (ATI) to angiotensin II (ATII). It is a medication used to treat high blood pressure, diabetic kidney disease, and heart failure. For heart failure, it is generally used with a diuretic such as furosemide. It is given by mouth or injection into a vein. The onset of effects is typically within an hour when taken by mouth and last for up today.

Mechanism of Action of Enalapril

Normally, angiotensin I is converted to angiotensin II by an angiotensin-converting enzyme (ACE). Angiotensin II constricts blood vessels, increasing blood pressure. Enalaprilat, the active metabolite of enalapril, inhibits ACE. Inhibition of ACE decreases levels of angiotensin II leading to less vasoconstriction and decreased blood pressure.

There are two isoforms of ACE: the somatic isoform, which exists as a glycoprotein comprised of a single polypeptide chain of 1277; and the testicular isoform, which has a lower molecular mass and is thought to play a role in sperm maturation and binding of sperm to the oviduct epithelium. Somatic ACE has two functionally active domains, N and C, which arise from tandem gene duplication. Although the two domains have high sequence similarity, they play distinct physiological roles. The C-domain is predominantly involved in blood pressure regulation while the N-domain plays a role in hematopoietic stem cell differentiation and proliferation. ACE inhibitors bind to and inhibit the activity of both domains, but have the much greater affinity for an inhibitory activity against the C-domain. Enalaprilat, the principal active metabolite of enalapril, competes with ATI for binding to ACE and inhibits and enzymatic proteolysis of ATI to ATII. Decreasing ATII levels in the body decreases blood pressure by inhibiting the pressor effects of ATII as described in the Pharmacology section above. Enalapril also causes an increase in plasma renin activity likely due to a loss of feedback inhibition mediated by ATII on the release of renin and/or stimulation of reflex mechanisms via baroreceptors. Enalaprilat’s affinity for ACE is approximately 200,000 times greater than that of ATI and 300-1000 times greater than that enalapril.

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Indications of Enalapril

Diabetic Nephropathies
High blood pressure (Hypertension)
Diabetic kidney disease
High blood pressure
Left ventricular dysfunction
Heart failure
Hypertensive emergency
Alport syndrome
Symptomatic congestive heart failure
Asymptomatic left ventricular dysfunction
Also for the treatment of essential or renovascular hypertension and symptomatic congestive heart failure. It may be used alone or in combination with thiazide diuretics.

Contra-Indications of Enalapril

Low amount of sodium in the blood
The high amount of potassium in the blood
An inherited disorder of continuing episodes of swelling
Reduction in the body’s resistance to infection
Decreased function of bone marrow
Decreased neutrophils a type of white blood cell
Narrowing of the aortic heart valve
Hypertrophic cardiomyopathy
Renal artery stenosis
Abnormally low blood pressure
Liver problems
Pregnancy
Brain blood flow problem
Hemodialysis with high-flux membrane

Dosage of Enalapril

Strengths: 2.5 mg; 5 mg; 10 mg; 20 mg; 1.25 mg/mL; 1 mg/mL

Hypertension

Initial dose (oral tablets or solution): 5 mg orally once a day
Maintenance dose (oral tablets or solution): 10 to 40 mg orally per day as a single dose or in 2 divided doses
Maximum dose: 40 mg orally daily as a single dose or in 2 divided doses

In combination with diuretics

Initial dose: 2.5 mg orally once a day
If feasible, the diuretic should be discontinued 2 to 3 days prior to initiation of therapy with enalapril. If required, diuretic therapy may be gradually resumed.
Parenteral: 1.25 to 5 mg IV over a 5 minute period every 6 hours

Congestive Heart Failure

Initial dose: 2.5 mg orally once a day
Maintenance dose: 2.5 to 20 mg daily in 2 divided doses
Maximum dose: 40 mg orally per day in 2 divided doses

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Pediatric Hypertension

Oral tablets or solution, Children 1 month to 17 years

Initial dose: 0.08 mg/kg/day (up to 5 mg) in 1 to 2 divided doses. Adjust dosage based on patient response.
Maximum dose: Doses greater than 0.58 mg/kg (40 mg) have not been evaluated in pediatric patients.

Side Effects of Enalapril

The most common

a severe headache, rapid heartbeat, stiffness in your neck,
chest pain, fast or slow heart rate;
swelling, rapid weight gain;
Xerostomia (dry mouth)
A headache
Fatigue
Skin reactions
Hypotension
Anxiety
Constipation
Nausea/vomiting
Weight gain/loss
Erectile dysfunction

More common

Abdominal or stomach pain, discomfort, or tenderness
chills or fever
difficulty with moving
a headache, severe and throbbing
joint or back pain
muscle aching or cramping
muscle pains or stiffness
chest pressure or squeezing pain in the chest
discomfort in arms, shoulders, neck or upper back
excessive sweating
feeling of heaviness, pain, warmth and/or swelling in a leg or in the pelvis
sudden tingling or coldness in an arm or leg
sudden slow or difficult speech
sudden drowsiness or need to sleep
fast breathing
sharp pain when taking a deep breath
fast or slow heartbeat
coughing up blood
rust colored urine
decreased amount of urine

Rare

Anxiety
change in vision
chest pain or tightness
confusion
a cough
Agitation
arm, back, or jaw pain
blurred vision
chest pain or discomfort
convulsions
extra heartbeats
fainting
hallucinations
a headache
irritability
lightheadedness
mood or mental changes
muscle pain or cramps
muscle spasm or jerking of all extremities
nervousness

Drug Interactions of Enalapril

Enalapril may interact with the following drugs, supplements, & may change the efficacy of drugs

allopurinol
alpha blockers (e.g., alfuzosin, doxazosin, tamsulosin)
alpha agonists (e.g., clonidine, methyldopa)
amphetamines (e.g., dextroamphetamine, lisdexamphetamine)
angiotensin II receptor blockers (ARBs; e.g., candesartan, losartan)
antidiabetes medications (e.g., insulin, metformin, glyburide)
atypical antipsychotics (e.g., clozapine, olanzapine, quetiapine, risperidone)
azathioprine
barbiturates (e.g., butalbital, pentobarbital phenobarbital)
beta-adrenergic blockers (e.g., atenolol, propranolol, sotalol)
calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
canagliflozin
ciprofloxacin
conivaptan
diuretics (water pills; e.g., furosemide, hydrochlorothiazide, triamterene)
duloxetine
“gliptin” diabetes medications (e.g., linagliptin, saxagliptin, sitagliptin)
heparin
iron dextran complex
iron gluconate
levodopa
medications that increase potassium levels (e.g., potassium supplements, spironolactone, amiloride, and salt substitutes containing potassium)
metformin
nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., ibuprofen, indomethacin, naproxen)
other angiotensin-converting-enzyme inhibitors (ACEIs; e.g., captopril, ramipril)
pentoxifylline
phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
pregabalin
sodium phosphates
temsirolimus
tizanidine
tolvaptan
trimethoprim

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Pregnancy Category of Enalapril

FDA Pregnancy Category D

Pregnancy

ACE inhibitors such as enalapril may cause severe harm or death to the developing fetus if taken by the mother during pregnancy. This medication should not be used during pregnancy. If you become pregnant while taking this medication, contact your doctor immediately.

Lactation

This medication passes into breast milk in small amounts. If you are a breast-feeding mother and are taking enalapril, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding. The safety and effectiveness of this medication have not been established for infants and children with decreased kidney function.