What is the proper way to write a prescription for lisinopril (angiotensin-converting enzyme inhibitor) for a typical adult patient with hypertension, potential heart failure, and possible impaired renal function?

How to Write a Lisinopril Prescription

Start lisinopril at 2.5-5 mg once daily for most patients, titrate every 2 weeks to a target dose of 20-40 mg once daily, and always check renal function and potassium within 1-2 weeks after initiation or dose changes. 1, 2

Initial Dosing Strategy

Standard Starting Doses by Indication

For hypertension without diuretic use:

• Start at 10 mg once daily in most adults 2
• Titrate to usual maintenance range of 20-40 mg once daily 2
• Maximum dose is 40 mg once daily (doses up to 80 mg have been studied but show no additional benefit) 2

For hypertension with concurrent diuretic therapy:

• Start at 5 mg once daily 2
• The lower starting dose prevents excessive hypotension from combined effects 2

For heart failure:

• Start at 5 mg once daily when used with diuretics and digitalis 2
• If hyponatremia present (serum sodium <130 mEq/L), start at 2.5 mg once daily 2
• Titrate as tolerated to maximum of 40 mg once daily 2

For post-myocardial infarction (within 24 hours):

• Give 5 mg orally initially, then 5 mg after 24 hours, 10 mg after 48 hours, then 10 mg once daily 2
• If systolic BP ≤120 mmHg and >100 mmHg during first 3 days, start at 2.5 mg 2
• Continue for at least 6 weeks 2

Critical Pre-Prescription Checks

Before writing the prescription, verify:

• Baseline creatinine and potassium levels (essential for dosing adjustments) 1
• Patient is not pregnant (absolute contraindication) 1
• No history of angioedema with ACE inhibitors 2
• Creatinine is not >221 μmol/L (>2.5 mg/dL) without specialist input 1
• Potassium is not >5.0 mmol/L 1
• Systolic blood pressure is not <90 mmHg 1

Dose Adjustments for Renal Impairment

Renal function-based dosing is mandatory:

• Creatinine clearance >30 mL/min: No adjustment needed 2
• Creatinine clearance 10-30 mL/min: Start at half the usual dose (5 mg for hypertension, 2.5 mg for heart failure) 2
• Creatinine clearance <10 mL/min or hemodialysis: Start at 2.5 mg once daily 2
• Maximum dose remains 40 mg daily after careful uptitration 2

Titration Protocol

Follow this systematic approach:

• Double the dose at intervals of not less than 2 weeks 1
• Aim for target dose of 20-40 mg once daily (30-35 mg cited in heart failure trials) 1
• Check blood chemistry (urea, creatinine, potassium) 1-2 weeks after initiation and after each dose increase 1
• Monitor blood pressure at each visit 1

Remember: Some ACE inhibitor is better than no ACE inhibitor—if target dose cannot be reached, maintain the highest tolerated dose 1

Monitoring Requirements

Essential laboratory monitoring:

• Renal function and potassium within 1-2 weeks after starting or increasing dose 1
• Ongoing monitoring every 3-6 months once stable 3
• An increase in creatinine up to 50% above baseline or to 3 mg/dL (266 μmol/L), whichever is greater, is acceptable 1
• If creatinine rises by 100% or exceeds 4 mg/dL, seek specialist advice 3

Common Pitfalls and Problem-Solving

Asymptomatic hypotension:

• Does not require treatment change 1
• Only intervene if symptomatic (dizziness, lightheadedness) 1

Symptomatic hypotension:

• First reconsider need for nitrates, calcium channel blockers, and other vasodilators 1
• Consider reducing diuretic dose if no signs of congestion 1
• Reduce lisinopril dose only if above measures fail 1

Hyperkalemia (K+ >5.5-6.0 mmol/L):

• Stop potassium supplements and potassium-sparing diuretics 1
• Avoid NSAIDs (can worsen hyperkalemia and cause renal impairment) 1
• Consider reducing or stopping lisinopril if persistent 1

Persistent dry cough:

• Cough is common in heart failure patients and may not be drug-related 1
• Exclude pulmonary edema as cause 1
• ACE inhibitor-induced cough rarely requires discontinuation 1
• If proven to be drug-related and intolerable, substitute with angiotensin receptor blocker 1

Drug Interactions to Avoid

Critical interactions:

• NSAIDs: Attenuate antihypertensive effect and increase risk of renal impairment 1
• Potassium supplements/potassium-sparing diuretics: Risk of hyperkalemia 1
• "Low-salt" substitutes with high potassium content: Risk of hyperkalemia 3
• Combination with ARB: Increases risk of hyperkalemia and renal dysfunction without mortality benefit 3
• Triple combination (ACE inhibitor + ARB + MRA): Absolutely contraindicated due to severe hyperkalemia risk 3

Patient Education Points

Counsel patients on:

• Expected benefits: improved symptoms within weeks to months, prevention of disease progression, increased survival in heart failure 1
• Report dizziness, lightheadedness, or symptomatic hypotension 1
• Avoid over-the-counter NSAIDs (ibuprofen, naproxen) 1
• Seek immediate care for facial swelling, difficulty breathing, or tongue swelling (angioedema) 2
• Women of childbearing age must use effective contraception (pregnancy is absolute contraindication) 1

Sample Prescription Format

Rx: Lisinopril 10 mg tablets

• Sig: Take 1 tablet by mouth once daily
• Disp: #30 tablets
• Refills: 3
• Follow-up: Check BP, creatinine, and potassium in 1-2 weeks