Chapter 23: Antihypertensive Drugs – Controlling Blood Pressure

Antihypertensive Drugs – Controlling Blood Pressure comprehensively details the pharmacological and nonpharmacological management of hypertension, defined as a persistent systolic pressure exceeding 140 mm Hg or diastolic pressure exceeding 90 mm Hg. The foundation of blood pressure regulation is explored through the autonomic nervous system (ANS) and its divisions, the sympathetic (SNS) and parasympathetic (PSNS), alongside the critical influence of cardiac output (CO) and systemic vascular resistance (SVR). Hypertension is categorized into primary (essential) hypertension, which is idiopathic, and secondary hypertension, which stems from underlying diseases. The therapeutic goal for most adults is a blood pressure below 140/90 mm Hg, with lower targets for patients with concurrent diabetes or chronic kidney disease. Nonpharmacological strategies, strongly supported by Canadian Hypertension Education Program (CHEP) guidelines, involve lifestyle changes such as achieving a healthy body mass index, following a DASH diet, restricting dietary sodium intake to less than 2,000 mg per day, and engaging in regular aerobic exercise. Pharmacological treatment utilizes seven main drug categories: diuretics (often first-line), adrenergic drugs (including alpha blockers, beta blockers, and centrally acting alpha2 agonists), Angiotensin-Converting Enzyme (ACE) inhibitors, Angiotensin II Receptor Blockers (ARBs), Calcium Channel Blockers (CCBs), vasodilators (such as sodium nitroprusside for emergencies), and direct renin inhibitors (aliskiren). Key mechanisms of action include ACE inhibitors blocking the conversion of angiotensin I to the potent vasoconstrictor angiotensin II and preventing the breakdown of the vasodilator bradykinin. ARBs, such as losartan, block the binding of angiotensin II to its receptors, offering a therapeutic alternative often used when the characteristic ACE inhibitor dry cough occurs. Nursing care throughout therapy requires meticulous assessment of orthostatic vital signs, monitoring for adverse effects like sexual dysfunction, and educating patients on the critical risk of rebound hypertension if medication is abruptly discontinued. Furthermore, patient response to therapy may vary based on ethnocultural background, necessitating tailored drug selection, where, for instance, patients of Black heritage may respond less favorably to ACE inhibitors and beta blockers than to diuretics and CCBs.