Cardiovascular Drugs

Question 1

Ace Inhibitor mode of action

Answer 1

Inhibit the action of angiotensin converting enzyme which converts angiotensin I into angiotensin II causing
* Vasoconstriction
* NaCl and H2O retention
* Increase BP

Positive effects
* Reduce BP
* Reduce afterload + preload
* Reduce proteinuria
* Prevent aberrant remodelling after MI

Question 2

ARB mode of action

Answer 2

Block the action of angiotensin II at the angiotensin AT1 receptor
* Reduce BP
* Reduce afterload
* Reduce proteinuria
* Prevent aberrant remodelling after MI

Question 3

CCB mode of action

Answer 3

Block L-type Ca2+ channel in myocytes of vasculature (peripherally acting) and heart (centrally acting)

• Depress phase 4 depolarisation in SA and AV nodes = ↓ HR
• Shorten phase 2 plateau phase = ↓contractility
  Centrally acting-> decrease HR + vasodilatation
  Peripherally acting-> decrease TPR and afterload

Question 4

Thiazide type diuretcs mode of action

Answer 4

Block reabsorption in distal convoluted tubule
Increase urinary excretion of Na
Decrease TPR – Vasodilatation

Question 5

Loop diuretics mode of action

Answer 5

Block NaCl reabsorption in ascending limb of loop of Henle – inhibit Na-K-Cl transporter
* Intense diuretic effect
* Vaso and venodilatation
- Work at very low GFR= ideal in HF

Question 6

Alpha adrenoreceptor antagonists

Answer 6

Selectively block post synaptic alpha 1 adrenoreceptors -> oppose vascular smooth muscle contraction in arteries

Causes
- Peripheral vasodilatation

Question 7

Antiplatelets mode of action

Answer 7

Aspirin
* Inhibits thromboxane A2

Clopidogrel, Ticagrelor, Prasugrel
* Inhibit P2Y12 ADP receptor

Fibrinogen receptor blockers

Question 8

DOACs (Direct Oral Anticoagulants) mode of action

Answer 8

DABIGATRAN-> direct thrombin inhibitor
Prevent fibrinogen-> fibrin

APIXABAN, EDOXABAN, RIVAROXABAN-> direct factor 10a inhibitors
Prevent prothrombin-> thrombin

Question 9

LMWH mode of action

Answer 9

• Factor 10a inhibitor
• First choice in cancer patients

Question 10

Beta blockers

Answer 10

Found in SA, AV nodes and myocytes

• Slows SA discharge and AV conduction-> prolongs phase 4 repolarisation
• Reduces excitability in non-nodal cardiac tissue-> ↓ ectopic firing
• Slow HR and conduction
• Increases diastolic filling time
• Reduces BP
• Decreases contractility (phase 2- Ca2+ entry)
• • Reduce renin secretion

Question 11

Vitamin K inhibitor mode of action

Answer 11

• Inhibits production of active clotting factors
  Used in prevention of DVT, PE, stroke
• In renal failure
• Significantly obese patients

Question 12

Nitrovasodilators eg GTN spray mode of action

Answer 12

Relax ALL smooth muscle by releasing NO -> reduce preload + afterload

Question 13

ACE inhibitor side effect

Answer 13

• Cough - to be switched with ARB

Question 14

ACE contraindications

Answer 14

• Renal artery stenosis-> may precipitate renal failure or infarction
• Impaired renal function
• Worsens hyperkalaemia
• Teratogenic

Question 15

CCB contraindications

Answer 15

• Acute MI
• Heart failure
• Bradycardia (rate limiting centrally acting CBBs)
• NEVER USE NIFEDAPINE IMMEDIATE RELEASE
• Unstable angina (dihydropyridines)

Question 16

CCB interactions

Answer 16

VERAPAMIL/DILTIAZEM
Used for
- AV nodal re-entrant tachycardia
- Rate control for A Fib and A flutter