Enalapril

Cardiovascular Drug

Drug class: Angiotensin Converting Enzyme Inhibitors, ACEI

Enalapril (RENITEC)（中文：依那普利）

Pronunciation

Enalapril 10mg

Enalapril 5mg

Common Strengths of Enalapril

Enalapril is available in the following strengths:

• 2.5 mg
• 5 mg
• 10 mg
• 20 mg

Drug Trade Names of Enalapril

The brand names for enalapril is Renitec.

Mechanism of Action

Enalapril is an inhibitor of angiotensin-1 converting enzyme (ACE inhibitor).

The beneficial effects of ACE inhibitors appear to result primarily from the suppression of the plasma renin-angiotensin-aldosterone system. Renin is synthesized by the kidneys and released into the circulation where it converts angiotensinogen to angiotensin-I. Angiotensin-I is then converted by angiotensin converting enzyme to angiotensin-II. Angiotensin-II is a potent vasoconstrictor responsible for arterial vasoconstriction and increased blood pressure, as well as for stimulation of the adrenal gland to secrete aldosterone.

Inhibition of ACE results in decreased plasma angiotensin-II, which leads to decreased vasopressor activity and to reduced aldosterone secretion.

Enalapril is used in the treatment of hypertension and heart failure. It may also be given prophylactically to patients with asymptomatic left ventricular dysfunction to delay the onset of symptomatic heart failure, and has been used in patients with left ventricular dysfunction to reduce the incidence of coronary ischaemic events, including myocardial infarction.

Route of Administration

Enalapril is administered orally as enalapril maleate.

Dosage

• Hypertension
  • Adult: Initially 5 mg once daily, lower initial doses may be required when used in addition to diuretic or in renal impairment; maintenance 20 mg once daily; maximum 40 mg/day.
• Heart failure
  • Adult: Initially 2.5 mg once daily, increased if tolerated to 10-20 mg twice daily, doses to be increased gradually over 2-4 weeks

Onset of antihypertensive activity was usually seen at 1 hour, with peak reduction of blood pressure achieved by 4 to 6 hours after administration.

The duration of effect is dose related. However, at recommended doses, antihypertensive and haemodynamic effects have been shown to be maintained for at least 24 hours.

Side Effects

Frequency	Adverse reactions
Common (≥1/100 to <1/10)	Dizziness
	Headache
	Taste alteration
	Depression
	Dry
	Irritating (non-productive) cough and dyspnoea
	Blurred vision
	Rush
	Oedema of the face, extremeties, lips, tongue, glottis and/or larynx
	Abdominal pain
	Nausea
	Diarrhoea
	Chest pain
	Arrhythmia
	Tachycardia
	Hypotension
Uncommon ( ≥1/1,000 to <1/100)	Confusion
	Insomnia
	Constipation
	Anorexia
	Peptic ulcer
	Flushing
Rare (≥1/10,000 to <1/1,000)	Stomatitis
	Small bowel angioedema
	Raynaud's syndrome
Very rare (<1/10,000)	Glossitis
	Pancreatitis

Pharmacokinetics

• Oral Enalapril is rapidly absorbed, with peak serum concentrations of enalapril occurring within 1 hour.
• Following absorption, oral enalapril is rapidly and extensively hydrolysed to enalaprilat, a potent angiotensin converting enzyme inhibitor. Peak serum concentrations of enalaprilat occur 3 to 4 hours after an oral dose of enalapril.
• The effective half-life for accumulation of enalaprilat following multiple doses of enalapril is 11 hours. In patients with normal renal function, steady state serum concentrations of enalaprilat were achieved by the fourth day of treatment.

Drug Management

Safety

For hypertension the first dose should preferably be given at bedtime.

Pregnancy

Should be avoided in pregnancy unless essential.

Breast Feeding

• Should avoid in the few weeks after delivery, particularly in preterm infants
  • Risk of profound neonatal hypotension
• Can be used in mothers breast-feeding older infants if essential.

Renal Impairment

Enalapril is a prodrug and requires close monitoring in patients with hepatic impairment.

• If eGFR < 30 mL/minute/1.73 m²
  • Max. initial dose 2.5 mg daily

Monitoring Requirements

Renal function and electrolytes should be checked before starting ACE inhibitors (or increasing the dose) and monitored during treatment (more frequently if side effects mentioned are present).

Drug Interactions

• Diuretics
  • Prior treatment with high dose diuretics may result in volume depletion and a risk of hypotension when initiating therapy with enalapril.
• Potassium sparing diuretics (triamterene, amiloride and spironolactone) or potassium supplement
  • May cause significant increase in serum potassium.

Caution

• Concomitant diuretics
  • First dose hypotension (especially in patients taking high doses of diuretics, on a low-sodium diet, on dialysis, dehydrated , or with heart failure)
• Use with care in those with a history of angioedema
• Use with care in patients with severe or symptomatic aortic stenosis (risk of hypotension)

FAQs

How should I take the tablet?

• Your doctor may advise you to take your first dose before bedtime, because it can make you dizzy. After the first dose, if you do not feel dizzy, you can take the tablet at any time of day. Try to take it at the same time every day.
• If you take enalapril twice a day, try to take it once in the morning and once in the evening. Leave 10 to 12 hours between doses if you can.
• You can take enalapril with or without food. Swallow the tablet whole with a drink of water.

What should I avoid while taking?

• Should avoid potassium rich foods.
  • Enalapril has the capacity to increase potassium level in the blood. High levels of potassium can lead to irregular heartbeat. It is better to avoid potassium-rich foods like bananas.

What happens if I miss a dose?

If you forget to take a dose and you usually take enalapril:

• Once a day – take it as soon as you remember unless it is less than 12 hours until your next dose. In this case leave out the missed dose and take your next dose at the usual time
• Twice a day – take it as soon as you remember unless it is less than 4 hours until your next dose. In this case leave out the missed dose and take your next dose at the usual time

Never take 2 doses to make up for a forgotten one.