ACE inhibitors and ARBs both target the RAAS but differ in mechanism, side effects, and specific uses — a common source of exam questions.
Mechanism
- ACE inhibitors: block Ang I → Ang II and prevent bradykinin breakdown (→ dry cough, angioedema)
- ARBs: block AT1 receptors selectively — no bradykinin effect, so little cough
Renoprotection
Both reduce efferent arteriolar resistance → lower intraglomerular pressure and proteinuria. First-line in diabetic nephropathy.
Both classes are contraindicated in pregnancy (renal tubular dysgenesis, oligohydramnios). Use labetalol or methyldopa instead.