Enalapril

Summary

Enalapril is a prescription ACE‑inhibitor prodrug used to lower blood pressure and improve outcomes in heart failure with reduced ejection fraction. It is administered orally or intravenously, and after conversion to the active metabolite enalaprilat it blocks the angiotensin‑converting enzyme, reducing vasoconstriction and aldosterone‑mediated fluid retention. Clinical research includes heart‑failure survival trials and a postpartum hypertension review, where it was compared with other antihypertensives.

Mechanism of Action

Enalapril is a dipeptide‑mimetic prodrug that is hydrolysed to the active ACE inhibitor enalaprilat. By binding to the active site of angiotensin‑converting enzyme, it prevents conversion of angiotensin I to the potent vasoconstrictor angiotensin II and reduces breakdown of bradykinin. The resulting decrease in angiotensin II lowers systemic vascular resistance and aldosterone secretion, leading to reduced blood pressure, afterload, and fluid retention. These actions underlie its use in hypertension and systolic heart‑failure management.

What the Research Shows

Randomised trials in heart failure have shown that enalapril improves survival. The SOLVD trial (1991) demonstrated a mortality benefit in patients with reduced left‑ventricular ejection fraction and congestive heart failure. In the PARADIGM‑HF trial, enalapril served as the active‑comparator against sacubitril/valsartan, confirming its established efficacy. A 2022 meta‑analysis of sacubitril/valsartan trials found no difference in atrial‑fibrillation prevention when enalapril was the control arm. A 2026 systematic review of postpartum hypertension included seven trials comparing enalapril with nifedipine; the evidence was low‑certainty and suggested greater need for additional antihypertensives when enalapril was used, though no safety concerns were reported.

Reported Benefits

Evidence from the SOLVD trial indicates that enalapril reduces mortality in systolic heart failure, establishing it as a cornerstone therapy for this condition. Its antihypertensive effect is supported by its inclusion in postpartum hypertension studies, although comparative effectiveness data are limited. The drug also serves as a standard reference arm in modern heart‑failure trials, confirming its continued clinical relevance.

Limitations of the Evidence

The postpartum hypertension review highlighted low‑certainty evidence and suggested enalapril may be less effective than nifedipine for non‑severe cases, with a higher need for additional agents. Data on atrial‑fibrillation prevention are limited to a non‑significant comparison with sacubitril/valsartan. Most efficacy data derive from older trials; newer comparative studies are scarce, and the systematic review noted insufficient information to guide optimal antihypertensive selection in the postpartum period.

Safety Considerations

The postpartum hypertension systematic review reported no safety concerns among the trials that included enalapril. Other cited trials did not detail adverse events in their abstracts, so specific safety information is limited. As with other ACE inhibitors, clinicians should be aware of class‑related risks such as hypotension, renal function changes, and hyper‑kalaemia, although these were not explicitly reported in the supplied literature.

How It Is Administered

Enalapril is available for oral administration as tablets and for intravenous use as the active metabolite enalaprilat. The oral prodrug is absorbed and converted in the liver to enalaprilat, which exerts the pharmacologic effect. Intravenous formulation delivers enalaprilat directly, allowing rapid onset in acute settings.

Routes of Administration

Goals & Uses

• Hypertension managementCardiovascularHigh
• Diabetic nephropathyRenalModerate
• Asymptomatic LV dysfunctionCardiovascularHigh
• Post-MI LV remodeling preventionCardiovascularModerate
• Heart failure treatmentCardiovascularHigh
• Heart failure (reduced EF)CardiovascularHigh

Contraindications

• Hereditary or idiopathic angioedemaImmunologic/AllergicModerate
• PregnancyPopulationHighPotential fetal risk or insufficient safety data
• Pregnancy (2nd and 3rd trimester)ObstetricHigh
• Concurrent aliskiren use in diabetes or CKD (eGFR <60)Drug InteractionHigh
• History of ACE inhibitor-induced angioedemaImmunologic/AllergicHigh
• Bilateral renal artery stenosisVascular/RenalHigh

Adverse Effects

• CoughRespiratoryCommonPersistent or episodic cough
• HypotensionCardiovascularUncommonLow blood pressure
• Renal impairment (acute)RenalUncommon
• Hypotension (first-dose)CardiovascularCommon
• HyperkalemiaElectrolyte ImbalanceUncommon
• Dry coughRespiratoryCommon
• AngioedemaImmunologicRare
• Dizziness/headacheNeurologicalCommon

Drug Interactions

• Non‑steroidal anti‑inflammatory drugs (NSAIDs)Low
• Potassium-sparing diuretics / potassium supplementsHigh
• Sacubitril (Entresto combination)High
• Potassium‑sparing diuretics (e.g., spironolactone)Moderate
• AliskirenHigh
• NSAIDsModerateMay increase renal risk in susceptible patients
• Antidiabetic agents (insulin, sulfonylureas)Low
• LithiumModerate

Population Constraints

• Chronic kidney disease (severe, eGFR <30)RenalRelative
• PregnancyReproductive SafetyAbsolute
• Neonates and infantsPediatricRelative
• Severe renal impairmentOrgan ImpairmentRelative
• Pregnant womenReproductiveAbsolute
• Elderly (>75 years)GeriatricRelative
• Bilateral renal artery stenosisVascularAbsolute

Regulatory Status

• European UnionApprovedApproved: Hypertension, Heart failureEMA approved; various brand names
• United StatesApprovedApproved: Hypertension, Heart failure, Left ventricular dysfunctionApproved by FDA; marketed as Vasotec
• United KingdomApprovedApproved: Hypertension, Heart failureMHRA approved

Approved in major jurisdictions; chemically a peptide‑mimetic dipeptide ester rather than a native peptide.

Evidence & Sources

• Postpartum management of the hypertensive disorders of pregnancy: a systematic review and meta-analysis
  Journal ArticleHighTol ID, et al.2026-01-01T00:00:00.000000Z
• Role of sacubitril-valsartan in the prevention of atrial fibrillation occurrence in patients with heart failure: A systematic review and meta-analysis of randomized controlled trials
  Journal ArticleHighLiu X, et al.2022-01-01T00:00:00.000000Z
• Angiotensin-neprilysin inhibition versus enalapril in heart failure
  Journal ArticleModerateMcMurray JJ, et al.2014-01-01T00:00:00.000000Z
• Effect of enalapril on survival in patients with reduced left ventricular ejection fractions and congestive heart failure
  Journal ArticleModerateSOLVD Investigators, et al.1991-01-01T00:00:00.000000Z
• Efficacy of folic acid therapy in primary prevention of stroke among adults with hypertension in China: the CSPPT randomized clinical trial
  Journal ArticleModerateHuo Y, et al.2015-01-01T00:00:00.000000Z
• Effects of enalapril on mortality in severe congestive heart failure. Results of the Cooperative North Scandinavian Enalapril Survival Study (CONSENSUS)
  Journal ArticleModerateCONSENSUS Trial Study Group1987-01-01T00:00:00.000000Z

Frequently Asked Questions