ACE Inhibitors: Therapeutic Effects and Side Effects

ACE Inhibitors

• Indications: hypertension, heart failure, and diabetic nephropathy
• Contraindications: pregnancy and bilateral renal artery stenosis
• Common side effects: cough, hyperkalemia
• Common drugs: lisinopril, enalapril, ramipril
• Bradykinin: a vasodilator, plays a role in reducing blood pressure and causes cough as a side effect

Angiotensin II Receptor Blockers (ARBs)

• Mechanism of action: block the action of angiotensin II at its receptor sites, leading to vasodilation and decreased aldosterone release
• Indications: hypertension, heart failure
• No dry cough or angioedema due to no effect on bradykinin levels
• Common drugs: losartan, valsartan, irbesartan

Angiotensin II (Ang II)

• Potent vasoconstrictor that increases blood pressure by constricting blood vessels and stimulating aldosterone release
• Dual action helps to lower blood pressure by reducing peripheral vascular resistance

Nebivolol

• Mechanism of action: stimulates the release of nitric oxide from the endothelium, leading to vasodilation and decreased blood pressure
• Nitric oxide relaxes the smooth muscle in blood vessels, leading to vasodilation

Centrally-acting Sympathetic Agents

• Mechanism of action: reduce sympathetic outflow from the brain, leading to a decrease in heart rate and blood pressure
• Common drugs: clonidine, methyldopa

Reserpine

• Mechanism of action: blocks the uptake of norepinephrine and dopamine into storage vesicles in sympathetic nerve terminals, leading to reduced sympathetic activity and decreased blood pressure

Carbonic Anhydrase Inhibitors

• Mechanism of action: block the enzyme carbonic anhydrase in the proximal convoluted tubule of the kidney, leading to decreased reabsorption of bicarbonate and sodium, resulting in metabolic acidosis
• Common indications: glaucoma, altitude sickness
• Common drugs: acetazolamide, dorzolamide

Loop Diuretics

• Mechanism of action: inhibit the reabsorption of sodium and chloride in the loop of Henle, leading to increased urine output
• Common indications: heart failure, hypertension, edema
• Side effects: metabolic alkalosis, hyponatremia, hypokalemia, hyperglycemia, hypocalcemia
• Common drugs: furosemide, torsemide, bumetanide

Thiazide Diuretics

• Mechanism of action: inhibit the reabsorption of sodium and chloride in the distal convoluted tubule, leading to increased urine output
• Common indications: hypertension, edema
• Side effects: metabolic alkalosis, hyponatremia, hypokalemia, hyperglycemia, hypercalcemia
• Common drugs: hydrochlorothiazide, chlorothiazide

Renin-Angiotensin-Aldosterone System (RAAS)

• Regulates blood pressure and fluid balance in the body
• Rate-limiting step: release of renin from the juxtaglomerular cells of the kidney
• Factors that stimulate the release of renin: decreased blood pressure, decreased sodium levels, sympathetic nervous system activation
• Renin acts on angiotensinogen to produce angiotensin I, which is converted to angiotensin II by ACE

Aliskiren

• Mechanism of action: direct renin inhibitor, blocks the conversion of angiotensinogen to angiotensin I, inhibiting the RAAS system
• Side effects: diarrhea, cough, hyperkalemia

Beta Blockers

• Mechanism of action: block beta 1 receptors in the heart, leading to decreased heart rate and contractility, reducing cardiac output and blood pressure
• Block beta 1 receptors in the kidney, reducing renin release and production of angiotensin II
• Common drugs: propranolol, metoprolol, atenolol

Nonspecific Alpha Blockers

• Mechanism of action: block both alpha 1 and alpha 2 receptors, leading to vasodilation and decreased blood pressure
• Indications: pheochromocytoma, hypertensive emergencies
• Common drugs: phentolamine

Alpha 1 Blockers

• Mechanism of action: block alpha 1 receptors, leading to vasodilation and decreased blood pressure
• Indications: hypertension, benign prostatic hyperplasia
• Common drugs: prazosin, doxazosin