Wk6 Angina

Question 1

Discuss the cause of angina

Answer 1

Angina - myocardial ischemia

Stable angina - atherosclerotic change in coronary arteries, need to reduce myocardial oxygen demands

Unstable angina - coronary spasm, plaques transfer to thrombus

Question 2

Discuss the treatment of stable angina

Answer 2

Acute attacks: organic nitrates
Prevention/prophylaxis: organic nitrates, CCBs, BBs
Treatment of underlying conditions: 
- antiplatelet, ie low dose aspirin
- BP control, ie ACEI
- lipid control, ie HMG-CoA inhibitors

Question 3

Discuss the mechanism of action of the organic nitrates, and explain their use in the treatment of angina

Answer 3

Organic nitrates: used in the acute/prophylactic treatment of stable angina
Drugs: glyceryl trinitrate, isosorbide mononitrate
MOA: vasodilator, dilate coronary vessels → improve O2 supply to the heart muscles
- Dilates arteries = reduces preload (makes it easier to pump)
- Dilates veins = reduces afterload (less to pump)
- Dilates coronary vessels

NP: available as sublingual tablets or transdermal patches → nitrates have a high first-pass effect

Question 4

Understand that tolerance may develop with the use of organic nitrates, and discuss their adverse drug reactions

Answer 4

Nitrate tolerance:

• nitrates may lose their clinical effectiveness when used as a sustained therapy
• having a nitrate-free period restores activity e.g. patch on at 8am, off at 8pm
• AEs: headache, dizziness, posture hypotension

Question 5

Describe why organic nitrates than you should not be used with phosphodiesterase type 5 inhibitors

Answer 5

• PDE5 inhibitors e.g. tadalafil, sildenafil (Viagra) – erectile dysfunction drugs
• Contraindicated – can cause profound hypotension, MI

Question 6

Discuss the mechanism of action of the calcium channel blockers, their adverse drug reactions, and their use in the treatment of angina

Answer 6

CCB:
Dihydropyridine - amlodipine, felodipine
Non-dihydropyridine - verapamil, diltiazem

MOA: ↓ HR&BP, dilate arteries, thus ↓ myocardial O2 demand

AEs: anticholinergic effects (headache, dizziness, hypotension, constipation), bradycardia with non-dihydropyridine

Question 7

Discuss the mechanism of action of beta blockers, their adverse drug reactions, and their use in the treatment of angina

Answer 7

Beta blocker (-prolol)
MOA: ↓sympathetic nervous responses → reduce HR, BP, cardiac contractility
- For prophylactic treatment of angina, not for acute attacks
- Initial therapy for angina. CCBA are alternatives – recommended when BB contraindicated

AEs: orthostatic hypotension, bronchospasm, bradycardia, cold extremities