Antihypertensive Agents

On this page

Overview & Diuretics - Water Pills Power

  • Hypertension (HTN): BP > 140/90 mmHg. Goal: ↓ target organ damage.
  • Lifestyle: DASH diet, exercise, ↓Na+, ↓alcohol, smoking cessation.
  • Diuretics: ↑Na+ & H2O excretion → ↓ blood volume → ↓ cardiac output → ↓ BP.
    • Thiazides (e.g., Hydrochlorothiazide/HCTZ, Chlorthalidone):
      • Site: Distal Convoluted Tubule (DCT).
      • Uses: Mild-moderate HTN, edema, nephrogenic DI.
      • SE: ↓K+, ↓Na+, ↑uric acid, ↑glucose, ↑lipids, ↑Ca2+ (hypercalcemia).

      ⭐ Thiazide diuretics can cause hypercalcemia (beneficial in osteoporosis) and are associated with hyperglycemia and hyperlipidemia.

    • Loop Diuretics (e.g., Furosemide, Torsemide):
      • Site: Thick Ascending Limb (TAL), Loop of Henle.
      • Uses: Severe HTN, CHF, pulmonary edema. Most potent.
      • SE: ↓K+, ↓Ca2+, ototoxicity, hyperuricemia. 📌 OH DANG (Ototoxicity, Hypokalemia, Dehydration, Allergy, Nephritis, Gout).
    • K+-sparing Diuretics:
      • Site: Collecting Duct (CD).
      • Types: Aldosterone antagonists (Spironolactone, Eplerenone); ENaC blockers (Amiloride, Triamterene).
      • Uses: HTN (with other diuretics), hyperaldosteronism.
      • SE: ↑K+. Spironolactone: gynecomastia. Nephron diagram showing diuretic sites of action

RAAS Inhibitors - Ace the Pressure

  • Classes: ACE Inhibitors (ACEIs), Angiotensin II Receptor Blockers (ARBs), Direct Renin Inhibitors (DRIs).
  • ACEIs ("-pril" e.g., Ramipril, Lisinopril):
    • MoA: Inhibit ACE → ↓ Angiotensin II, ↑ Bradykinin.
    • Side Effects: Dry cough, angioedema (bradykinin-mediated), hyperkalemia, teratogenic, first-dose hypotension. 📌 PRIL: Potassium ↑, Rash, Increased cough, Low BP.
  • ARBs ("-sartan" e.g., Losartan, Telmisartan):
    • MoA: Block AT1 receptors for Angiotensin II.
    • Side Effects: Hyperkalemia, teratogenic; less cough & angioedema vs ACEIs.
  • DRIs (Aliskiren):
    • MoA: Directly inhibits renin activity.
    • Side Effects: Diarrhea, hyperkalemia, teratogenic.
  • Key Uses: Hypertension, Heart Failure, Diabetic Nephropathy, Post-MI.

⭐ ACE inhibitors are contraindicated in patients with bilateral renal artery stenosis due to the risk of acute renal failure. RAAS pathway and antihypertensive drug targets

Calcium Channel Blockers - Smooth Muscle Relaxers

  • Mechanism: Block L-type Ca²⁺ channels → ↓ intracellular Ca²⁺ → vascular smooth muscle relaxation (vasodilation) & ↓ myocardial contractility/conduction.
  • Types:
    • Dihydropyridines (DHPs): e.g., Amlodipine, Nifedipine. Primarily potent vasodilators.
      • Uses: Hypertension, angina.
      • SE: Peripheral edema, flushing, headache, reflex tachycardia.
    • Non-Dihydropyridines (Non-DHPs):
      • Verapamil (cardioselective), Diltiazem (intermediate).
      • Uses: Hypertension, angina, supraventricular tachyarrhythmias (SVTs).
      • SE: Bradycardia, AV block, constipation (esp. Verapamil), gingival hyperplasia.

⭐ Verapamil and Diltiazem (non-DHP CCBs) can cause constipation and gingival hyperplasia, and should be used cautiously with beta-blockers due to risk of heart block.

  • Other Uses: Prinzmetal's angina, Raynaud's phenomenon. Calcium Channel Blockers: Classification, Uses, Side Effects

Sympatholytics & Vasodilators - Nerve & Vessel Agents

  • Centrally Acting ($α_2$ Agonists)
    • Clonidine: ↓ Sympathetic outflow. AE: Rebound HTN, sedation.
    • Methyldopa: Prodrug. AE: Coombs +ve hemolytic anemia.
  • $α_1$ Blockers (Selective)
    • Prazosin, Doxazosin: Vasodilation. AE: First-dose hypotension.
  • $α$ & $β$ Blockers
    • Labetalol, Carvedilol: Vasodilation + ↓ HR.
  • Direct Arterial Vasodilators
    • Hydralazine: ↑ cGMP. AE: Drug-induced lupus, reflex tachycardia.
    • Minoxidil: K+ channel opener. AE: Hypertrichosis (📌 Minoxidil for MAX hair), reflex tachycardia.
  • Arterial & Venous Vasodilator
    • Sodium Nitroprusside: Releases NO. AE: ⚠️ Cyanide toxicity.

⭐ Labetalol and Methyldopa are preferred antihypertensives during pregnancy; Sodium Nitroprusside is used in hypertensive emergencies but carries a risk of cyanide toxicity with prolonged use.

High‑Yield Points - ⚡ Biggest Takeaways

  • Thiazides: First-line; cause hypokalemia, hyperuricemia, hyperglycemia.
  • ACEIs/ARBs: Preferred in DM, CKD; cause cough (ACEI), hyperkalemia; contraindicated in pregnancy.
  • CCBs (Dihydropyridines) like Amlodipine: Cause pedal edema, gingival hyperplasia, reflex tachycardia.
  • Beta-blockers: Post-MI, HF; avoid in asthma, heart block; mask hypoglycemia symptoms.
  • Hydralazine can cause drug-induced lupus; Minoxidil can cause hirsutism.
  • Sodium Nitroprusside: For hypertensive emergencies; risk of cyanide toxicity with prolonged use.

Practice Questions: Antihypertensive Agents

Test your understanding with these related questions

The choice of antihypertensive medication also depends upon the co-morbid illness of the patient, and all of the following recommendations have been made except:

1 of 5

Flashcards: Antihypertensive Agents

1/10

Cardiovascular (Antihypertensives) _____ and angiotensin II receptor blockers are first line treatment for hypertension in patients with heart failure, MI, and/or diabetes

TAP TO REVEAL ANSWER

Cardiovascular (Antihypertensives) _____ and angiotensin II receptor blockers are first line treatment for hypertension in patients with heart failure, MI, and/or diabetes

ACE inhibitors

browseSpaceflip

Enjoying this lesson?

Get full access to all lessons, practice questions, and more.

Start Your Free Trial