Antihypertensive Drugs

• Antihypertensives are medications used to lower blood pressure
• High blood pressure (hypertension) increases the risk of heart disease, stroke, kidney disease, and other health problems
• The main goal of antihypertensive therapy is to reduce these risks by lowering blood pressure to a target level determined by guidelines and individual patient factors

Classes of Antihypertensive Drugs

• Diuretics: Increase urine production, helping to reduce blood volume and lower blood pressure

  • Thiazide diuretics (e.g., hydrochlorothiazide, chlorthalidone): Commonly used as first-line treatment for hypertension; work by inhibiting sodium reabsorption in the kidneys
  • Loop diuretics (e.g., furosemide, bumetanide): More potent diuretics, typically used in patients with heart failure or kidney disease
  • Potassium-sparing diuretics (e.g., spironolactone, amiloride): Help prevent potassium loss, often used in combination with other diuretics

• Angiotensin-Converting Enzyme (ACE) Inhibitors: Block the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor

  • Examples include: enalapril, lisinopril, ramipril
  • Reduce blood pressure by relaxing blood vessels and decreasing blood volume
  • Common side effect: dry cough; other side effects include: angioedema and hyperkalemia
  • Contraindicated in pregnancy

• Angiotensin II Receptor Blockers (ARBs): Block angiotensin II from binding to its receptors

  • Examples include: losartan, valsartan, irbesartan
  • Similar effects to ACE inhibitors but with a lower risk of cough
  • Also contraindicated in pregnancy

• Beta-Blockers: Block the effects of adrenaline on the heart and blood vessels

  • Examples include: metoprolol, atenolol, propranolol
  • Reduce heart rate and cardiac output, thereby lowering blood pressure
  • Used cautiously in patients with asthma or COPD; can mask symptoms of hypoglycemia
  • Not typically used as first-line therapy unless there are specific indications such as: angina, heart failure, or migraine

• Calcium Channel Blockers (CCBs): Prevent calcium from entering smooth muscle cells in blood vessels and the heart

  • Dihydropyridines (e.g., amlodipine, nifedipine): Primarily affect blood vessels, causing vasodilation
    • Common side effects: peripheral edema, headache, flushing
  • Non-dihydropyridines (e.g., verapamil, diltiazem): Affect both the heart and blood vessels, reducing heart rate and contractility
    • Used in patients with arrhythmias or angina

• Alpha-Blockers: Block alpha-adrenergic receptors, leading to vasodilation

  • Examples include: prazosin, terazosin, doxazosin
  • Often used in patients with hypertension and benign prostatic hyperplasia (BPH)
  • Common side effect: orthostatic hypotension

• Central Alpha-Agonists: Reduce sympathetic outflow from the brain

  • Examples include: clonidine, methyldopa
  • Less commonly used due to side effects such as: sedation and dry mouth
  • Methyldopa is sometimes used in pregnancy

• Vasodilators: Directly relax blood vessels

  • Examples include: hydralazine, minoxidil
  • Often used in combination with other antihypertensives
  • Minoxidil can cause excessive hair growth (hypertrichosis)

Combination Therapy

• Many patients require more than one medication to achieve target blood pressure

• Combining drugs from different classes can be more effective and minimize side effects

• Common combinations include:

  • ACE inhibitor or ARB with a diuretic
  • ACE inhibitor or ARB with a calcium channel blocker
  • Beta-blocker with a diuretic

Lifestyle Modifications

• Lifestyle changes are an important part of managing hypertension

  • Weight loss: Reduces blood pressure and improves overall health
  • Dietary changes: Following the DASH (Dietary Approaches to Stop Hypertension) diet, which is low in sodium, saturated fat, and cholesterol, and high in fruits, vegetables, and low-fat dairy
  • Regular exercise: Aim for at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic exercise per week
  • Limiting alcohol consumption: Moderate alcohol intake (up to one drink per day for women and up to two drinks per day for men)
  • Smoking cessation: Smoking increases blood pressure and the risk of cardiovascular disease

Monitoring and Follow-Up

• Regular monitoring of blood pressure is essential
• Patients should be educated on how to monitor their blood pressure at home
• Follow-up appointments are needed to adjust medications and assess for side effects
• Blood tests may be necessary to monitor kidney function, electrolytes, and other parameters

Special Populations

• Elderly: Start with low doses and titrate slowly; be cautious of orthostatic hypotension
• African Americans: May respond better to thiazide diuretics and calcium channel blockers than to ACE inhibitors as initial monotherapy
• Patients with diabetes: ACE inhibitors or ARBs are often used first-line to protect kidney function
• Patients with kidney disease: ACE inhibitors or ARBs are used to slow the progression of kidney disease; monitor kidney function closely
• Pregnant women: Certain antihypertensives (e.g., methyldopa, labetalol, nifedipine) are preferred; ACE inhibitors, ARBs, and diuretics are contraindicated