Reviewed by MedNext Clinical Team
ACE inhibitors have transformed the management of cardiovascular and renal disease over the past four decades. Ramipril, one of the most extensively studied agents in its class, reduces mortality in heart failure, improves outcomes after myocardial infarction, and provides renal protection in diabetic nephropathy. Understanding its mechanism, appropriate monitoring, and common adverse effects is essential for any prescriber [1].
Mechanism of Action
Ramipril inhibits angiotensin-converting enzyme (ACE), preventing the conversion of angiotensin I to angiotensin II. This reduces vasoconstriction and aldosterone secretion, lowering both preload and afterload on the heart. Additionally, ACE inhibitors reduce the breakdown of bradykinin, which contributes to vasodilation but also underlies their most common adverse effect — dry cough.
Key Indications
Heart Failure with Reduced Ejection Fraction (HFrEF)
ACE inhibitors are first-line therapy in HFrEF, reducing mortality and hospitalisation. Ramipril is typically initiated at 1.25–2.5 mg once or twice daily and titrated up to a target of 10 mg daily, as tolerated.
Post-Myocardial Infarction
The HOPE trial demonstrated that ramipril 10 mg daily significantly reduced the risk of MI, stroke, and cardiovascular death in high-risk patients, even those without pre-existing left ventricular dysfunction [1]. It should be started within days of an acute MI when the patient is haemodynamically stable.
Diabetic and Non-Diabetic Nephropathy
ACE inhibitors reduce intraglomerular pressure by dilating the efferent arteriole, slowing progression of proteinuric kidney disease. An initial rise in creatinine of up to 30% is acceptable and expected — it does not indicate treatment failure.
Adverse Effects and Monitoring
Dry Cough
Affecting 10–15% of patients (and up to 30–40% in East Asian populations), dry cough results from bradykinin accumulation in the lungs. It resolves on discontinuation. Patients who cannot tolerate an ACE inhibitor due to cough should be switched to an angiotensin receptor blocker (ARB), which does not affect bradykinin.
Hyperkalaemia
By reducing aldosterone, ACE inhibitors promote potassium retention. Monitor serum potassium and renal function at baseline, 1–2 weeks after initiation or dose changes, and periodically thereafter. Exercise caution when combining with potassium-sparing diuretics, potassium supplements, or NSAIDs.
First-Dose Hypotension
Patients who are volume-depleted (e.g., on high-dose diuretics) are at risk of significant hypotension with the first dose. Advise patients to take the first dose at bedtime, ensure adequate hydration, and consider withholding diuretics for 24 hours before initiation in high-risk individuals.
Angioedema
A rare but potentially life-threatening complication affecting approximately 0.1–0.3% of patients. ACE inhibitors are absolutely contraindicated in patients with a history of ACE inhibitor-induced angioedema. Unlike cough, switching to an ARB does not fully eliminate angioedema risk and should be approached with caution.
When to Switch to an ARB
ARBs (e.g., losartan, candesartan, valsartan) block the angiotensin II receptor directly and offer equivalent cardiovascular and renal protection to ACE inhibitors with a significantly lower incidence of cough. They are the preferred alternative when ACE inhibitor cough is intolerable. The combination of an ACE inhibitor and ARB is not recommended due to increased risk of hyperkalaemia, hypotension, and renal impairment without additional mortality benefit.
References
- Heart Outcomes Prevention Evaluation Study Investigators. Effects of an angiotensin-converting-enzyme inhibitor, ramipril, on cardiovascular events in high-risk patients. NEJM. 2000;342:145-153.