Antihypertensives

Mechanisms by class

Antihypertensive drug classes act at different points in blood pressure regulation - ACE inhibitors/ARBs (renin-angiotensin system blockade), calcium channel blockers (vascular smooth muscle relaxation), diuretics (reduced circulating volume), and beta-blockers (reduced cardiac output/renin release) - class selection is guided by patient comorbidity and compelling indications rather than blood pressure lowering potency alone
ACE inhibitors/ARBs block angiotensin II formation/action, reducing vasoconstriction and aldosterone-driven sodium retention - providing specific renoprotective benefit in diabetic/proteinuric kidney disease beyond blood pressure lowering alone, explaining their preferred status in this population
Calcium channel blockers (dihydropyridines) relax vascular smooth muscle with minimal cardiac conduction effect, while non-dihydropyridines also slow AV nodal conduction - this distinction matters for combination therapy and for patients with concurrent arrhythmia

Amongst the most widely prescribed medication classes globally given hypertension's very high population prevalence

Compelling indications (diabetic nephropathy favouring ACE inhibitor/ARB, heart failure favouring specific evidence-based agents, angina favouring beta-blocker or calcium channel blocker) should guide first-line agent selection over blood pressure lowering potency alone
ACE inhibitor/ARB combination is avoided given increased hyperkalaemia and acute kidney injury risk without added efficacy benefit demonstrated in trials

Renal function and potassium monitoring after starting/up-titrating ACE inhibitors or ARBs, given the expected (usually modest and acceptable) initial eGFR fall and hyperkalaemia risk
Angioedema (ACE inhibitor-specific, bradykinin-mediated, not fully cross-reactive with ARBs) requires immediate cessation and avoidance of re-challenge given recurrence risk
ACE inhibitor-associated angioedema (bradykinin-mediated, a specific serious adverse effect), ACE inhibitor/ARB combination therapy harm (avoided per trial evidence), compelling indication-based agent selection, beta-blocker relative contraindication in reactive airway disease

ACE inhibitor and ARB combination therapy should be avoided - despite both targeting the renin-angiotensin system, trial evidence demonstrated increased hyperkalaemia and acute kidney injury risk with combined blockade without a corresponding efficacy benefit, making this a specific, frequently tested prescribing error to avoid

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