What are the classifications of anti-hypertensive (high blood pressure) medications?

Classifications of Antihypertensive Medications

Antihypertensive medications are classified into several major categories based on their mechanisms of action, with each class having specific indications, contraindications, and clinical applications. The primary classes include diuretics, ACE inhibitors, ARBs, calcium channel blockers, beta-blockers, and others, each playing important roles in blood pressure management 1.

Major Classes of Antihypertensive Medications

1. Diuretics

• Thiazide and Thiazide-like Diuretics: First-line agents for most patients with hypertension, especially effective in elderly patients and those with isolated systolic hypertension 1
• Compelling indications: Elderly patients, isolated systolic hypertension, heart failure, secondary stroke prevention 1
• Compelling contraindications: Gout (though may sometimes be necessary with allopurinol) 1
• Examples: Chlorthalidone (preferred due to longer half-life), hydrochlorothiazide 2

2. Angiotensin Converting Enzyme (ACE) Inhibitors

• Compelling indications: Heart failure, left ventricular dysfunction post-myocardial infarction, established coronary heart disease, Type 1 diabetic nephropathy 1
• Possible indications: Chronic renal disease, Type 2 diabetic nephropathy, secondary stroke prevention 1
• Compelling contraindications: Pregnancy, renovascular disease 1
• Examples: Lisinopril, enalapril 2, 3

3. Angiotensin II Receptor Blockers (ARBs)

• Compelling indications: ACE inhibitor intolerance, Type 2 diabetic nephropathy, heart failure in ACE intolerant patients 1
• Possible indications: Left ventricular dysfunction after myocardial infarction, proteinuric renal disease, chronic renal disease 1
• Compelling contraindications: Pregnancy 1
• Examples: Losartan, candesartan 2, 4

4. Calcium Channel Blockers (CCBs)

• Dihydropyridine CCBs:
  • Compelling indications: Elderly patients, isolated systolic hypertension 1
  • Possible indications: Angina 1
  • Examples: Amlodipine, nifedipine (though capsule form should no longer be prescribed) 1, 2
• Rate-limiting (Non-dihydropyridine) CCBs:
  • Compelling indications: Angina 1
  • Possible indications: Elderly patients 1
  • Compelling contraindications: Heart block, heart failure 1
  • Examples: Verapamil, diltiazem 5

5. Beta-Blockers

• Compelling indications: Myocardial infarction, angina 1
• Possible indications: Heart failure (though may worsen heart failure in some cases) 1
• Compelling contraindications: Asthma, chronic obstructive pulmonary disease, peripheral vascular disease, diabetes (except with coronary heart disease) 1
• Note: No longer considered first-line for uncomplicated hypertension due to reduced stroke prevention compared to other agents 2

6. Alpha-Blockers

• Compelling indications: Benign prostatic hyperplasia 1, 6
• Cautions: Postural hypotension, heart failure when used as monotherapy 1
• Compelling contraindications: Urinary incontinence 1
• Examples: Doxazosin, prazosin 6, 5

7. Direct Renin Inhibitors

• Used for treatment of hypertension 7
• Example: Aliskiren 7
• Contraindicated with ARBs or ACEIs in patients with diabetes 7

8. Centrally Acting Agents

• Act by diminishing sympathetic outflow from the vasomotor center 8
• Examples: Clonidine, methyldopa 5, 8

9. Direct Vasodilators

• Act directly on blood vessels to cause vasodilation 5
• Examples: Hydralazine, minoxidil 5, 8

Treatment Approach and Combinations

• For stage 1 hypertension (140-159/90-99 mmHg), thiazide-type diuretics are recommended for most patients; may consider ACE inhibitor, ARB, beta-blocker, or CCB 1
• For stage 2 hypertension (≥160/≥100 mmHg), a 2-drug combination is recommended (usually thiazide-type diuretic plus ACE inhibitor, ARB, beta-blocker, or CCB) 1
• The AB/CD algorithm can guide treatment decisions:
  • A (ACE inhibitors/ARBs) or B (beta-blockers) are more effective in younger white patients
  • C (calcium channel blockers) or D (diuretics) are more effective in older white patients and black patients of any age 1
• Logical two-drug combinations include: (A or B)+(C or D) 1, 2

Special Population Considerations

• Black patients: Initial therapy should include a thiazide-type diuretic or CCB 2, 9
• Diabetes patients: ACE inhibitors or ARBs are preferred, especially with albuminuria 1, 2
• Chronic kidney disease: ACE inhibitors or ARBs are preferred, particularly with albuminuria ≥300 mg/day 1, 2
• Resistant hypertension: Consider adding a mineralocorticoid receptor antagonist (e.g., spironolactone) 2

Common Pitfalls to Avoid

• Avoid simultaneous use of ACE inhibitors and ARBs, which increases adverse effects without additional benefit 1, 2
• Avoid nifedipine in capsule form 1
• Consider drug interactions and patient-specific factors when selecting antihypertensive medications 9
• Beta-blockers should not be used as first-line therapy unless specific indications exist (e.g., coronary artery disease, heart failure) 2, 9