Understanding ACE Inhibitors and ARBs for Hypertension Management

Side Effects and Clinical Pearls

A notable side effect of ACE inhibitors is a dry cough, which occurs in approximately 5–20% of patients. This is thought to be caused by the accumulation of bradykinin or substance P in the respiratory tract.

Exam Tip: If a patient on an ACE inhibitor presents with a persistent, non-productive dry cough, the clinician may consider switching them to an ARB, which does not typically cause this side effect.

Angiotensin Receptor Blockers (ARBs)

ARBs serve as an alternative to ACE inhibitors, providing similar benefits for hypertension and heart failure.

Mechanism of Action

Unlike ACE inhibitors, which prevent the production of Angiotensin II, ARBs work by blocking the binding of Angiotensin II directly at its receptors. This blockade prevents the downstream effects of Angiotensin II, such as vasoconstriction and the secretion of aldosterone.

Common examples include Candesartan (Atacand®), Irbesartan (Avapro®), Losartan (Cozaar®), Telmisartan (Micardis®), and Valsartan (Diovan®).

CRITICAL SAFETY NOTE: ACE inhibitors and ARBs should never be used in combination. Combining these drugs increases the risk of renal impairment and hypotension.

Clinical Benefits: Cardioprotection and Renal Protection

Beyond simply lowering blood pressure, both ACE inhibitors and ARBs offer significant organ-protective benefits.

Cardioprotective Effects

These drugs are "drugs of choice" for patients with heart failure. They help reduce morbidity and mortality by:

• Reducing Preload and Afterload: Decreasing the workload on the heart.
• Preventing Ventricular Remodeling: They slow the progression of left ventricular hypertrophy (the thickening of the heart muscle) that often occurs following a myocardial infarction (MI).

Renal Protective Effects

For patients with diabetes, these drugs are standard therapy to prevent the progression of diabetic nephropathy. They achieve this by:

• Reducing glomerular filtration pressure.
• Reducing proteinuria (the presence of excess proteins in the urine).

Hypertension Management in Black Individuals

Clinical practice requires race- and ethnicity-conscious care, particularly regarding hypertension management. Hypertension in Black individuals is often more common, has an earlier onset, and is more severe compared to White individuals.

Clinical Considerations

Current guidelines suggest that, in the absence of other compelling indications, Black patients should typically be started on a diuretic or a Calcium Channel Blocker (CCB) rather than an ACE inhibitor. This recommendation is based on two primary factors:

1. Low Renin Responders: Individuals of Black heritage are often "low renin responders," meaning they may be less responsive to therapies that target the RAAS.
2. Angioedema Risk: There is evidence suggesting an increased risk of angioedema (a potentially fatal swelling of the deeper layers of the skin) in Black patients using ACE inhibitors. The incidence is reported at 0.43% for Black people compared to 0.18% for non-Black people.

Summary of Adverse Effects and Interactions

While generally well-tolerated, clinicians must monitor patients for several potential issues:

Drug Interactions

• Potassium-sparing diuretics or supplements: Can lead to additive effects, causing dangerous hyperkalemia.
• Lithium: ACE inhibitors/ARBs can inhibit the elimination of lithium, leading to increased lithium levels and potential toxicity.
• NSAIDs: These can have opposing effects on blood pressure and may increase the risk of renal dysfunction.