ACE Inhibitors vs ARBs

ACE Inhibitors vs ARBs

Clinical Tips for a Pharmacist

  • ACEI 1st-line in HF & post-MI unless cough/angioedema
  • Always check baseline SCr, eGFR, K⁺ before starting either class
  • Avoid dual ACEI + ARB therapy (↑ hyperkalemia & kidney injury – NO added benefit)
  • In Black patients – can use as first-line BUT may require combo w/ thiazide or CCB to reach BP target
  • Consider ARB for patients on NSAIDs long-term → slightly lower risk of renal vasoconstriction
  • Olmesartan – rare sprue-like enteropathy (chronic diarrhea, weight loss) – discontinue if suspected
Feature ACE Inhibitors ARBs
Examples Lisinopril, Enalapril, Ramipril, Captopril, Perindopril, Benazepril Losartan, Valsartan, Olmesartan, Irbesartan, Telmisartan, Candesartan, Azilsartan
Mechanism of Action Inhibits angiotensin-converting enzyme → ↓ Ang II production → ↓ vasoconstriction + ↓ aldosterone + ↑ bradykinin Blocks AT1 receptor → prevents Ang II-mediated vasoconstriction & aldosterone release (no bradykinin effects)
Clinical Use – Adult HTN, HFrEF (1st line), CKD with albuminuria, Post-MI (mortality benefit), Diabetic nephropathy HTN (1st line), CKD w/ albuminuria, Alternative in ACEI-intolerant pts (cough/angioedema), HF (valsartan, candesartan), Post-MI (if ACEI intolerant)
Time to BP Effect 2–4 weeks full effect 2–4 weeks full effect
Effect on Kidney Protection Strong evidence in diabetic nephropathy and CKD albuminuria reduction Similar benefit, slightly less bradykinin-mediated renal vasodilation
ADR – Common Cough (5–20%), dizziness, hypotension, ↑ SCr, hyperkalemia Well tolerated; dizziness, ↑ SCr, hyperkalemia
ADR – Unique/Serious Dry cough, angioedema risk higher, taste disturbance (captopril), neutropenia (rare) Angioedema (rare vs ACE-I but still possible), slightly ↑ hypotension in volume depletion
Pregnancy CI – box warning (fetal toxicity) CI – fetal toxicity
Black Box Warning Pregnancy → fetal injury/death Pregnancy → fetal injury/death
Onset/Duration Pearls Enalapril (prodrug), Captopril short-acting → TID Telmisartan longest t½ (24h) → good for adherence
Renal Dose Adjustment Yes – adjust in CKD; avoid initiation in acute kidney injury Usually no dose change needed in renal impairment (except losartan caution GFR <30)
Initiation Precautions Do not initiate if K⁺ >5.5 or SCr ↑ >30% at baseline, avoid in bilateral renal artery stenosis Same monitoring but safer in ACEI-intolerant; use caution with renal artery stenosis
Monitoring Parameters SCr & potassium at baseline and within 1–2 weeks after initiation and dose titration; BP; angioedema symptoms Same – BP, SCr, K⁺ after 1–2 weeks; edema/cough (very low incidence)
Drug-Drug Interactions NSAIDs ↓ effect & ↑ renal injury; K⁺-sparing diuretics ↑ hyperkalemia; Lithium ↑ toxicity; Aliskiren CI in diabetes Same → NSAIDs, lithium, K⁺-supplements; fewer bradykinin-related interactions
Switching Guidance If cough or angioedema → switch to ARB (except severe angioedema → wait 4–6 wks before trial) Start low → titrate q2–4 weeks
Advantages Strong mortality HF evidence; long-standing clinical experience Better tolerated, less cough, less angioedema; once-daily BP control superior in some agents
Disadvantages Cough → limits adherence; more angioedema; renal dosing required Cost (brand-only options), slower titration in HF
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