Hypertension 3

Question 1

What is the MOA of Calcium Channel Blockers (CCBs)?

What are the indications of CCBs?

Answer 1

• Work by blocking voltage-gated calcium channels in cardiac muscle and blood vessels
  
  • calcium is prevented from entering muscle cells, inhibiting the muscle contraction
• Indications
  
  • angina
  • some types of abnormal heart rhythms

Question 2

What are the classes and subclasses of CCBs?

Answer 2

• Dihydropyridine (‘dipine’)
• Non-dihydropyridine
  
  • phenylalkylamine CCBs
  • benzothiazepine CCBs

Question 3

Describe Dihydropyridines

Answer 3

• Used to reduce systemic vascular resistance and thus arterial pressure
• e.g. nifedipine, isradipine

Question 4

Describe non-dihydropyridines

Answer 4

• Slow down heart rate
• indications: arrhythmia
• Further subdivided into:
  
  • phenylalkylamine CCBs:
    
    • selective for myocardium e.g. verapamil
  • benzothiazepine CCBs:
    
    • intermediate class in terms of their selectivity (both heart and vasculature) e.g. diltiazem

Question 5

What are the ADRs of ACE inhibitors?

Answer 5

• Hypotension
• Headache
• Fatigue
• Hyperkalemia
• Dizziness
• Nausea
• Renal impairment
• Cough
  
  • associated with increases in bradykinin (BK) levels caused by ACE inhibitors

Question 6

What is the triple whammy effect?

Answer 6

• ACE inhibitor + diuretic + NSAID = possible renal failure
• Renal blood flow affected by ATII, which increases GFR
  
  • by reducing ATII levels, ACE inhibitors may reduce GFR, a marker of renal function
    
    • a problem if the patient is also taking a NSAID and a diuretic
      
      • high risk of developing renal failure

Question 7

Describe the effect of each drug on the triple whammy effect

Answer 7

• ACE inhibitor
  
  • dilates the efferent arteriole, and reduces GFR
• Diuretic
  
  • Reduce plasma volume and GFR
• NSAID
  
  • Constrict blood flow into the glomerulus via the afferent arteriole and reduce GFR

Question 8

What is the MOA of centralling-acting alpha agonists?

What are their indications?

Answer 8

• Lower blood pressure by stimulating alpha 2-receptors in brain to indirectly relax peripheral arteries easing blood flow
• Usually administered with a diuretic
• Reduce sympathetic activity
• Clonidine: prescribed when all other anti-hypertension medications have failed
• Methyldopa: prodrug, hypertension during pregnancy

Question 9

Which drugs to use for hypertension?

Answer 9

1. Diuretics
2. ARBs (or ACEI)
3. Beta blockers
4. CCBs

Question 10

Column 1

Column 2

Answer 10

• Column 1
  
  • CCB*
  • Thiazide Diuretic
• Column 2
  
  • Beta blocker
  • ACE inhibitor
  • ARB

*use w/ caution when combining a non-dihydropyridine CCB (e.g. verapamil) w/ beta blocker, due to potential for bradycardia or cardiac conduction disturbances (e.g. heart block)

Question 11

What is dual therapy?

Answer 11

• Combine one agent from column 1 and one agent from column 2

Question 12

What is triple therapy?

Answer 12

• Combine two agents from column 1 with one agent from column 2