Chapter 42: Antihypertensive Drugs & Blood Pressure Control

Antihypertensive Drugs & Blood Pressure Control from Pharmacology: A Patient-Centered Nursing Process Approach provides a comprehensive examination of the pharmacologic control of hypertension, grounding the discussion in the physiologic mechanisms that regulate blood pressure, including the kidneys, baroreceptors, and the Renin-Angiotensin-Aldosterone System (RAAS). It outlines the Joint National Committee (JNC 8) guidelines for blood pressure targets, distinguishing between essential hypertension, often linked to risk factors like obesity and diet, and secondary hypertension resulting from renal or endocrine disorders. The text systematically categorizes antihypertensive drugs into seven primary groups, beginning with diuretics—particularly thiazides—which are frequently used as first-line agents to reduce extracellular fluid volume. It explores sympatholytics in depth, covering beta-adrenergic blockers that lower cardiac output and vascular resistance, centrally acting alpha2 agonists that reduce sympathetic outflow, and alpha-adrenergic blockers noted for their dual utility in treating benign prostatic hypertrophy (BPH). The summary details the mechanisms of direct-acting arteriolar vasodilators, such as hydralazine and the potent nitroprusside used for hypertensive emergencies, while addressing adverse effects like reflex tachycardia and fluid retention. Significant attention is dedicated to agents affecting the RAAS, specifically Angiotensin-Converting Enzyme (ACE) inhibitors and Angiotensin II Receptor Blockers (ARBs), highlighting critical side effects such as the ACE-induced cough, hyperkalemia, and the risk of angioedema. The chapter also covers direct renin inhibitors and Calcium Channel Blockers (CCBs), differentiating between phenylalkylamines, benzothiazepines, and dihydropyridines. Throughout the text, the nursing process is emphasized, focusing on patient safety regarding orthostatic hypotension, the risks of rebound hypertension from abrupt discontinuation, drug-food interactions (such as grapefruit juice with CCBs), and important cultural variations in drug response, particularly among African American and Asian populations.