Class 1 Anti-Arrhythmics Flashcards
1
Q
Examples: Class 1A
A
- Quinidine
- Disopyramide
2
Q
Example: Class 1B
A
- Lidocaine
3
Q
Example: Class 1C
A
- Flecainide
4
Q
Indications of class 1’s?
A
- Tachyarrhythmias
5
Q
What are the contraindications of class 1A’s?
A
- Heart failure
- Heart block
- Ischaemic heart disease (flecainide)
6
Q
Cautions for use of class 1’s?
A
- Pregnancy
- Prostatic enlargement
- Glaucoma
- Hepatic impairment
- Renal impairment
7
Q
How do class 1’s work?
A
- Inhibit sodium channels
8
Q
How do A, B and C differ if they act on the same channels?
A
- They have different speeds of binding
9
Q
What effect do 1A’s (quinidine and disopyramide) have?
A
- Prolong cardiac action potential
10
Q
What effect do 1B’s (lidocaine) have?
A
- Shorten cardiac action potential
11
Q
What effect do 1C’s (flecainide) have?
A
- Do not affect action potential
12
Q
How are class 1’s administered?
A
- Oral or IV depending on circumstance
13
Q
What adverse reactions are there for class 1 anti arrhythmics?
A
- Arrhythmogenic and may prolong QT interval
- Anticholinergic effects
- Seizures (flecainide)
14
Q
How are some class 1’s metabolised?
A
- Through the cytochrome P450 system so very susceptible to drug interactions
15
Q
What drugs should you avoid copharmacy with?
A
- Drugs that may prolong QT interval (e.g. amiodarone, antihistamines)
- Drugs which have a negatively ionotropic effect
