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 ↓Demand: ↓HR, ↓contractility ↑Supply: ↓HR	AV block, heart failure