2008A08 Define the mechanisms of action and adverse effects of metoprolol, glyceryl trinitrate and diltiazem when used to manage myocardial ischaemia.

 

 

Mechanism of action

Adverse effects

Metoprolol

β1 selective antagonist

↓Demand: ↓HR, ↓contractility, offset by compensatory ↑afterload

↑Supply: ↓HR, offset by ↓mAP but that too offset by ↑SVR

↓AV node conduction

↓cardiac output

↓mAP

Worsen peripheral vascular disease

Bronchospasm (β2 antagonism)

↓tremor, depression, fatigue, insomnia, sexual dysfunction, migraine prophylaxis

↑risk diabetes, ↓ autonomic response to ↓BSL, ↓ symptoms of ↓BSL (tremor, ↑HR)

Hair loss

GTN

NO donor

↓Demand: ↓preload, ↓afterload

↑Supply: coronary vasodilatation -> ↑Coronary blood flow

Headache, flushing, dizziness

Nausea, vomiting

↓Blood pressure, syncope

Reflex ↑HR

Methaemoglobinaemia

Diltiazem:

Non-dihydropyrine L-Ca2+ antagonist

Mainly cardiac effect

↓Supply: ↓HR, ↓contractility

AV block, heart failure

 

 

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