Hypertension and Antihypertensive Medications PDF

Introduction This document provides information on anti-hypertensive medications, including their mechanisms of action, comparative profiles, clinical uses, adverse effects, and cautions/contraindications. It also discusses the prevalence of hypertension and its associated risks. The document furthe...

Introduction This document provides information on anti-hypertensive medications, including their mechanisms of action, comparative profiles, clinical uses, adverse effects, and cautions/contraindications. It also discusses the prevalence of hypertension and its associated risks. The document further highlights the different types and severities of hypertension, as well as the complications that can arise if left untreated. First-line anti-hypertensive medications: • ACE inhibitors (Angiotensin-Converting Enzyme inhibitors) • MOA: Inhibit the conversion of angiotensin I to angiotensin II, reducing vasoconstriction and aldosterone release • Comparative profiles: Effective in reducing blood pressure, well-tolerated • Clinical uses: Hypertension, heart failure, post-myocardial infarction, diabetic nephropathy • AE: Cough, hyperkalemia, angioedema • CI: Pregnancy, bilateral renal artery stenosis • ARBs (Angiotensin Receptor Blockers) • MOA: Block the binding of angiotensin II to its receptors, leading to vasodilation and reduced aldosterone release • Comparative profiles: Similar efficacy to ACE inhibitors, better tolerated • Clinical uses: Hypertension, heart failure, diabetic nephropathy • AE: Hyperkalemia, hypotension • CI: Pregnancy • Thiazide diuretics • MOA: Inhibit sodium reabsorption in the distal convoluted tubules, leading to increased urinary sodium and water excretion • Comparative profiles: Effective in reducing blood pressure, often used in combination therapy • Clinical uses: Hypertension, heart failure, edema • AE: Hypokalemia, hyponatremia, hyperuricemia • CI: Severe renal impairment, electrolyte abnormalities • Calcium channel blockers • • • • • MOA: Inhibit calcium entry into vascular smooth muscle cells, leading to vasodilation Comparative profiles: Effective in reducing blood pressure, well-tolerated Clinical uses: Hypertension, angina, arrhythmias AE: Edema, constipation, dizziness CI: Severe hypotension, heart block Special situations: • Elderly: Consider lower doses and monitor for orthostatic hypotension • Specific race: African Americans may benefit from calcium channel blockers or diuretics • HT emergencies: Nitroprusside, labetalol, or nicardipine may be used • Pregnancy: Methyldopa, labetalol, nifedipine may be used Complications of hypertension: • End-stage organ damage: Affects arterioles leading to complications such as stroke, heart attack, kidney failure • High blood pressure and eye disease: Can cause damage to the retina Sites of blood pressure regulation: • • • • Resistance - regulated by arterioles Capacitance - regulated by postcapillary venules (capacitance vessels) Pump output - regulated by the heart Volume - regulated by the kidneys Coordination among these sites: • Baroreflexes (mediated by sympathetic nerves of the ANS) • Renin-angiotensin-aldosterone system (RAAS) Effects of lifestyle changes on blood pressure: • • • • • Nutrition (DASH eating plan): 8-14 mm Hg reduction in systolic blood pressure Nutrition (dietary sodium restriction): 2-8 mm Hg reduction Physical activity: 4-9 mm Hg reduction Weight loss: 5-20 mm Hg reduction Moderation of alcohol consumption: 2-4 mm Hg reduction Non-pharmacological approaches: • DASH (Dietary Approaches to Stop Hypertension), Mediterranean diet • Physical activity and behavioral therapies Classes of antihypertensive drugs: • • • • • • Sympathetic agents: central A2 agonists CCBs (calcium channel blockers): Verapamil, diltiazem, nifedipine Beta-blockers (reduce cardiac output): Propranolol, Atenolol Alpha-1 blockers: Prazosin, doxazosin, terazosin Direct vasodilators (for severe cases) RAAS inhibitors: ACE inhibitors (Ramipril, Enalapril, Lisinopril), ARBs (Losartan, valsartan, telmisartan) • Diuretics: Thiazides (Chlorthalidone, Hydrochlorothiazide), Loop diuretics (Furosemide), Potassium-sparing diuretics (Spironolactone) Angiotensin Converting Enzyme Inhibitors (ACEI) • • • • Block conversion of angiotensin I to angiotensin II Reduces vasoconstriction and aldosterone secretion Used to treat hypertension and heart failure Adverse effects: cough, angioedema, hyperkalemia Angiotensin Receptor Blockers (ARB) • Selectively inhibit angiotensin II's type 1 (AT1) receptor • Blocks the actions of angiotensin II, causing vasodilation • Used to treat hypertension Adverse effects of Aliskiren: • K+ imbalance • Teratogenic Mechanism of action of Aliskiren: • • • • Direct renin inhibitor in the renin-angiotensin system Prevents the conversion of angiotensinogen to angiotensin I Reduces renin release from the kidneys Drops blood pressure and fluid volume Adverse effects of ACE inhibitors: • Dry cough • Angioedema Mechanism of action of ACE inhibitors: • Inhibits ACE, which inactivates vasodilator bradykinin • Acts on angiotensin I to form angiotensin II • Reduces blood pressure and narrows blood vessels Adverse effects of beta blockers: • Bradycardia • Decreased libido • CNS: vivid dreams, depression Mechanism of action of beta blockers: • Block beta-1 receptors on the heart, reducing cardiac output • Block beta-1 receptors on juxtaglomerular cells in the kidney, inhibiting renin release • Decrease blood pressure and peripheral vascular resistance Adverse effects of alpha-1 adrenergic blockers: • Postural hypotension (first dose effect) • Blurred vision (miosis) Mechanism of action of alpha-1 adrenergic blockers: • Block alpha-1 receptors in arterioles and venules, causing relaxation of vascular smooth muscle • Reduce peripheral vascular resistance Adverse effects of central alpha-2 agonists: • Dry mouth Mechanism of action of central alpha-2 agonists: • Act on alpha-2 receptors in the brain stem to reduce sympathetic outflow • Reduce heart rate and blood pressure Stages of hypertension and corresponding mode of treatment: • • • • Normal BP: No treatment Elevated BP: Lifestyle changes Stage 1 HT: Non-pharm + BP meds Stage 2 HT: Non-pharm + BP meds First-line treatment of HTN: • Thiazide diuretics, ACE inhibitors, ARBs, or long-acting CCBs • Combination therapy with an ACE inhibitor and a long-acting CCB is popular Hydralazine and Cough • Hydralazine is a medication used to treat high blood pressure • One of the potential side effects of hydralazine is cough Drugs for High Blood Pressure • ACE inhibitors (such as lisinopril) can be used to treat high blood pressure • They have a teratogenic (ability to cause birth defects) potential of 1.1 Beta Blockers and Calcium Channel Blockers • Beta blockers and calcium channel blockers (B blocws CCB) are also used to treat high blood pressure ARB and Potassium • ARBs (Angiotensin II receptor blockers) can be used to treat high blood pressure • They have a teratogenic potential (ability to cause birth defects) related to potassium (K) Blood Pressure • High blood pressure (BP) is a condition that needs to be managed