Cardiac Drugs Flashcards
1
Q
Aspirin
A
- Aspirin prevents formation of PGs which both inhibits (blocks thromboxane A2) and promotes aggregation (blocks prostacycline)
- Thromboxane is reduced for lifespan of the platelet
- Prostacycline inhibition is reversible
- Twice weekly, 100-600mg, enteric coating
2
Q
Purinergic antagonists
A
- Antiplatelets
- ADP induced platelet aggregation by activating P2Y12 receptors
- Activation –> decreased cAMP –> increased platelet aggregation
- Eg. Clopidogrel
3
Q
Clopidogrel
A
- Anti-platelet via P2Y12 receptor
- Prodrug
- Converted by CYP enzymes
- Prevention of ischaemic events with symptomatic atherosclerosis
4
Q
GP IIb/IIIa inhibitors
A
- Prevent fibrinogen cross-linking of platelets
- Abiciximab
- Tirofiban
5
Q
Direct thrombin inhibitors
A
- Do not rely on endogenous anticoagulant systems
- Dabigatran
- Prevention of venous thromboembolism and non-valvular AF
- Gastric effects
6
Q
Rivaroxaban
A
- inhibits factor Xa
- similar usage to Dabigatran
7
Q
Heparins
A
- Not absorbed by gut –> IV or subcutaneous
- Enhances anti-thrombin –> inactivation of Xa and thrombin
- Prevention of venous thrombus, treatment of venous thromboembolism, peripheral arterial occlusion, acute coronary syndrome
- Main risk haemorrhage
8
Q
Vitamin K antagonists
A
- Vit K required for synthesis of factors II, VII, IX, X
- Warfarin
9
Q
Warfarin
A
- Competes with Vit K for binding at VKORC1
- Metabolised by CYP2C9
- Peak pharm effect 48h
- Requires monitoring
- P450 interaction
- Crosses placenta
10
Q
Fibrinolytics
A
- Cleave plasminogen to plasmin
- Plasmin digests fibrin, fibrinogen, ECM proteins, clotting factors
- Dissolve clots and reopen occluded arteries
- Patient with acute MI <12h
- Alteplase
- IV
- Major risk of bleeding
11
Q
Class I Anti-arrhythmics
A
- Block Na channels
- Bind to a subunit to prevent Na entry
- Slow conduction velocity of pacemaker potentials
- Used for tachyarrhythmias
12
Q
Class 1a antiarrhythmics
A
- Disopyramide –> life-threatening tachycardias
- Quinidine
- Slows phase 0 of CAP
- Increases refractory period
13
Q
Class 1b antiarrhythmics
A
- Fast <0.5s
- Limited effects on conduction velocity
- Lignocaine –> serious ventricular arrhythmias
- More activity with increased HR
14
Q
Class 1c anti-arrhythmics
A
- Slow
- Flecainide
- Slows cardiac conduction esp in ventricles
- Prolongs PR and QRS intervals
- AF, atrial flutter, SVT
- CI: heart block, MI
15
Q
Class 2 antiarrhythmics
A
- Anti-sympathetic effect at SA and AV nodes
- Atenolol
- Metoprolol
- Tachycardias
- Also neg inotrope –> reduced Ca influx
16
Q
Ivabradine
A
- Angina
- Chronic heart failure
- Inhibits If
- Negative chonotrope
17
Q
Class 3 antiarrhythmics
A
- Prolong cardiac action potential
- Block K outward channels
- Increases refractory period
- Prevents re-entrant tachycardia
- Supresses ectopic activity
- Eg. Amiodarone
18
Q
Amiodarone
A
- Class 3
- Reduces automaticity
- Prolongs PR and QT intervals
- Prolongs refractory periods
- Serious tachycardias
- Inhibits CYP2C9, CYP2D6 àmultiple drug interactions
- Very long elimination half life (10-100 days)
19
Q
Sotalol
A
- Dual class II/III
- Blocks b adrenoreceptors and K channel
- Treatment and prevention of atrial, SV and ventricular arrhythmias
20
Q
Class 4 antiarrhythmics
A
- Ca channel antagonists
- Slow the conduction of SA and AV nodes
- Reduce contractile force
- Verapamil, Diltiazem
21
Q
Verapamil
A
- Class 4
- Greater cardiac effects
- SVT, AF, atrial flutter
22
Q
Diltiazem
A
- Class 4
- Acts on cardiac and vascular smooth muscle
- Less cardiac effects than verapamil
23
Q
Atropine
A
- Competitive antagonist of muscarinic receptors
- Treatment of bradycardia and haemodynamic compromise
- Removes parasympathetic brake on HR
- Reverse SLUDGE BBB effects
24
Q
Isoprenaline
A
- B agonist
- Positive inotrope, positive chonotrope
- Heart block
- Bradycardia with haemodynamic compromise
25
Digoxin
* Increases ventricular output
* Positive inotrope
* HF and some arrhythmias
* Long elimination time
* Narrow TR
