Hypertension Medications and Related Concepts

Pathophysiology and Pharmacology - Hypertension Medications

Instructor: Hannah Ferguson, FNP-BC, MSN, RN

Learning Objectives

  • Identify classes and MOA of drugs used to treat hypertension.
  • Provide patient education for safe and effective hypertension medication administration.
  • Recognize common side effects and adverse effects of medications used to treat hypertension.

Factors Impacting Blood Pressure

  • Increase in BP:

  • Stroke Volume

  • Heart Rate

  • Blood Viscosity

  • Vessel Length

  • Decrease in BP:

  • Increase in vessel radius (vasodilation)

Thiazide & Related Diuretics: Hydrochlorothiazide

  • Mechanism of Action:

  • Inhibits NaCl reabsorption in the distal convoluted tubule.

  • Decreases extracellular fluid and systemic vascular resistance.

  • Lowers BP moderately over 2-4 weeks.

  • Side Effects/Adverse Effects:

  • Volume depletion, Hypokalemia, Hyponatremia

  • Dehydration, Vertigo, Headache, Weakness

  • Gastrointestinal issues: Anorexia, N/V/D, Constipation

  • Often first choice for essential hypertension, particularly beneficial in heart failure (HF).

  • Nursing Considerations:

  • Monitor for orthostatic hypotension and hypokalemia.

  • Risk for cardiotoxicity with digoxin; mitigate hypokalemia with potassium-rich foods.

  • Be aware of NSAIDs that may decrease drug effectiveness.

  • Monitor for hyperglycemia, especially in diabetic patients.

Loop Diuretics: Furosemide

  • Mechanism of Action:

  • Inhibits NaCl reabsorption in the ascending limb of the loop of Henle.

  • More potent than thiazides but shorter duration of action.

  • Side Effects/Adverse Effects:

  • Severe volume depletion, Hypokalemia, Hyponatremia

  • Gastrointestinal issues: Dehydration, similar to thiazides.

  • Helpful in HF with pulmonary edema when thiazides are ineffective.

  • Nursing Considerations:

  • Monitor serum potassium levels, effective even in renal insufficiency.

  • Increased diuretic effect with higher doses.

Angiotensin-Converting Enzyme Inhibitors: Lisinopril

  • Mechanism of Action:

  • Inhibits ACE, reducing conversion of angiotensin I to angiotensin II.

  • Prevents vasoconstriction and renal absorption of water and sodium.

  • Side Effects/Adverse Effects:

  • Hypotension (especially upon first dose), dizziness, cough.

  • Loss of taste, hyperkalemia, acute renal failure, angioedema.

  • Nursing Considerations:

  • NSAIDs may reduce effectiveness; diuretics can enhance action.

  • Monitor BUN/Creatinine; be cautious in patients with renal impairment.

  • Use cautiously with potassium-sparing diuretics due to hyperkalemia risk.

Angiotensin II Receptor Blockers: Losartan

  • Mechanism of Action:

  • Blocks angiotensin II action, leading to vasodilation and increased excretion of salt and water.

  • Side Effects/Adverse Effects:

  • Angioedema, decreased renal function, fetal harm in later pregnancy.

  • Nursing Considerations:

  • Full BP effect may take 3-6 weeks; alternative for patients with cough from ACE inhibitors.

Beta-Blockers: Metoprolol, Propranolol

  • Mechanism of Action:

  • Reduces BP by antagonizing beta-adrenergic effects; lowers heart rate and contractility.

  • Side Effects/Adverse Effects:

  • Hypotension, bronchospasm, AV conduction block, nightmares, depression, erectile dysfunction.

  • Nursing Considerations:

  • Monitor pulse and BP regularly; caution in diabetic patients due to risk of hypoglycemia.

  • Non-selective beta-blockers pose a risk of bronchospasm.

Calcium Channel Blockers: Nifedipine, Verapamil

  • Mechanism of Action:

  • Block calcium movement into cells, resulting in vasodilation and decreased heart rate.

  • Side Effects/Adverse Effects:

  • Bradycardia, AV block, nausea, dizziness, peripheral edema.

  • Nursing Considerations:

  • Caution in heart failure patients; avoid grapefruit with nifedipine.

Alpha-1-Adrenergic Blockers: Prazosin

  • Mechanism of Action:

  • Produce peripheral vasodilation, decreasing systemic vascular resistance (SVR) and BP.

  • Side Effects/Adverse Effects:

  • Variable orthostatic hypotension; may cause profound hypotensive episodes.

  • Nursing Considerations:

  • Reduces urinary resistance in benign prostatic hyperplasia (BPH); take at bedtime to reduce orthostatic risks.

Central Acting Alpha-2 Agonists: Clonidine, Methyldopa

  • Mechanism of Action:

  • Reduces sympathetic outflow from the CNS and peripheral sympathetic tone, leading to vasodilation.

  • Side Effects/Adverse Effects:

  • Dry mouth, sedation, erectile dysfunction, nausea, dizziness.

  • Nursing Considerations:

  • Sudden discontinuation may lead to rebound hypertension; provide education on gradual tapering.

Case Study Overview

Patient Information
  • 70 y/o Asian American female, Weight 160 lbs, Height 5 ft
  • Symptoms: Nauseated, fever over 102°F, vomiting for 4 days, confusion, poor skin turgor.
  • Vital signs: BP 171/97, HR 107, Temp 102.2°F
  • Lab Values: Glucose 585, Elevated Na+ and Serum Osmolality, Ketones 3.1.
Actions to Take
  • Administer fluids and insulin as ordered for Diabetic Ketoacidosis (DKA).
  • Monitor Intake and Output; assess blood glucose levels.
  • Teach patient about medications especially in relation to hypertension management.
  • Monitor vital signs; administer potassium as ordered.
Parameters to Monitor
  • I&O due to dehydration, Blood glucose levels, Neurological status.
  • Use clean technique for IV insertions to prevent complications.
  • Ensure education on medication adherence once symptoms allow for oral intake.