What is the use of Enalapril (Angiotensin-Converting Enzyme (ACE) inhibitor) in treating medical conditions?

Use of Enalapril

Enalapril is a first-line ACE inhibitor indicated for treating hypertension, symptomatic heart failure (NYHA class I-IV), and asymptomatic left ventricular dysfunction, where it reduces mortality, hospitalizations, and improves quality of life. 1, 2

Primary Indications

Heart Failure

• Enalapril is indicated for all patients with symptomatic congestive heart failure (NYHA class I-IV), typically combined with diuretics and digitalis. 1, 2
• The drug increases survival, improves symptoms, and decreases hospitalization frequency in symptomatic heart failure patients. 2
• In asymptomatic left ventricular dysfunction (ejection fraction ≤35%), enalapril decreases the rate of developing overt heart failure and reduces hospitalization incidence. 1, 2
• Major trials (CONSENSUS I, SOLVD-T) demonstrated that ACE inhibitors increase survival, reduce hospital admissions by 99 per 1000 patient-years, and prevent 13 deaths per 1000 patient-years. 1
• The SOLVD prevention trial showed enalapril significantly reduced heart failure incidence and related hospital admissions in asymptomatic patients with left ventricular systolic dysfunction. 1

Hypertension

• Enalapril is effective for treating all grades of hypertension (mild to severe), either alone or combined with thiazide diuretics. 2, 3
• The blood pressure lowering effects of enalapril and thiazides are approximately additive. 2
• Enalapril reduces peripheral vascular resistance without increasing heart rate. 4, 3

Post-Myocardial Infarction

• In patients with ejection fractions ≤40% after acute MI, enalapril reduces mortality and prevents heart failure development. 1

Dosing Algorithm

Starting Dose

• Begin enalapril at 2.5 mg twice daily in heart failure patients. 1
• For hypertension, initiate at 2.5 mg twice daily. 1
• Lower starting doses are critical in patients with hypotension (systolic BP 70-90 mm Hg), though asymptomatic hypotension is not a contraindication. 1

Titration Schedule

• Double the dose at intervals of not less than 2 weeks. 1
• Titrate gradually to the target dose of 10-20 mg twice daily. 1
• The target dose should be 10 mg twice daily for most patients. 1
• Higher doses (up to 20 mg twice daily) reduce the combined endpoint of death or hospitalization more effectively than lower doses. 1

Monitoring Requirements

• Check renal function (creatinine) and serum potassium within 1-2 weeks of initiation and periodically thereafter. 1, 5
• Monitor blood pressure at each dose adjustment. 1
• More frequent monitoring is warranted in high-risk patients with pre-existing hypotension, hyponatremia, diabetes mellitus, azotemia, or those taking potassium supplements. 1, 5

Contraindications and Cautions

Absolute Contraindications

• History of angioedema with previous ACE inhibitor exposure. 1
• Pregnancy. 1
• Anuric renal failure. 1

Seek Specialist Advice Before Initiating

• Significant renal dysfunction (creatinine >2.5 mg/dL or >221 μmol/L). 1
• Hyperkalemia (>5.0 mmol/L). 1
• Symptomatic or severe asymptomatic hypotension (systolic BP <90 mm Hg). 1
• Bilateral renal artery stenosis. 1

Important Caveat

• Continue enalapril unless serum creatinine rises by more than 30% within 4 weeks following initiation or dose increase. 5
• A small increase in creatinine and potassium is expected and does not require discontinuation. 1

Clinical Benefits and Outcomes

Mortality and Morbidity

• In the SOLVD-Treatment trial, enalapril produced an 11% reduction in all-cause mortality and 30% reduction in heart failure hospitalization. 2
• In NYHA class IV heart failure (CONSENSUS trial), 6-month survival was 74% with enalapril versus 56% with placebo; 1-year survival was 64% versus 48%. 2

Quality of Life

• Enalapril produces modest but significant improvements in NYHA functional class, symptoms of dyspnea and fatigue, and overall quality of life in symptomatic heart failure. 6, 7
• In hypertension, enalapril maintains or slightly improves quality of life from baseline. 6

Common Pitfalls to Avoid

Underdosing

• Aim for target doses proven in clinical trials (10-20 mg twice daily), not just symptom control. 1
• Remember: some ACE inhibitor is better than no ACE inhibitor if target doses cannot be tolerated. 1

Premature Discontinuation

• Asymptomatic low blood pressure does not require dose reduction or discontinuation. 1
• ACE inhibitor-induced cough rarely requires treatment discontinuation; exclude pulmonary edema first. 1

Inadequate Monitoring

• Failure to check baseline renal function and electrolytes before starting therapy is a common error. 5
• Not reassessing labs within 1-2 weeks after initiation or dose changes. 5

Diuretic Management

• Ensure appropriate diuretic dosing before and during ACE inhibitor therapy, as fluid retention blunts therapeutic effects while fluid depletion potentiates adverse effects. 1
• If hypotension occurs without signs of congestion, consider reducing diuretic dose before stopping enalapril. 1