Antiarryhthmics Flashcards
Quinidine Adverse
Class 1 Sodium channel blocker
**Cinchonism (named after tree that anti malarials come from-Quinines-so seen in any antimalarials only BUZZ WORD) - Tinnitus, ocular dysfunction (cannot tell if miosis or mydriasis because it is both a muscarinic and alpha blocker), CNS excitation, GI disturbances (same as eyes explanation)
Hypotension
Prolongation of QRS and QT interval - Torsades *****
Quinidine General
Class IA Sodium channel blocker
- muscarinic receptor blocker
- alpha bloc (possible reflex tachycardia)
- wide clinical use in many arrhthymias; in atrial fibrillation, need initial digitalization (to slow AV conduction)
Quinidine drug interactions
Class 1 sodium channel blocker
- Hyperkalemia enhances effects and vice versa
- Displaces digoxin from tissue binding sites
Procainamide Description
Class 1A Sodium channel blocker
- Less muscarinic receptor block than quinidine
- Metabolized through conjugation by N-acetyltransferase
- -therefore affected by slow/fast metabolizers
Procainamide Adverse
Class 1 Sodium channel blockers
SLE like syndrome
Hematotoxicity
CV effects (torsades)
Torsades caused by what type of drugs?
Anti muscarinic
SLE like syndrome is caused by what drugs?
Procainamide
Hydralazine (anti HTN)
Isoniazid (anti TB)
-seen in slow acetylators
Drug induced SLE lab results
Positive anti ANA
Positive anti histone** (specific to drug induced)
Negative anti dsDNA
Disopyramide
Class 1A sodium channel blocker
Class 1B Drugs
Sodium channel blockers
-Block fast sodium channels (decrease
-Block inactivated channels (slow conduction in hypoxic and ischemic heart) -slows cells ability to go back to resting
-Decrease APD - due to block of the slow sodium “window” currents
Lidocaine, Mexiletine
Lidocaine cardio uses
Class1 B
- post MI
- Open heart surgery
- Digoxin toxicity*
Lidocaine adverse
Class 1B CNS toxicity (seizures); least cardiotoxic of conventional anti arrhythmics ***IV only*** (due to first pass metabolism)
Mexiletine and Tocainide
Class 1B drugs
Same as lidocaine
Oral formulations
Class 1C
Second choice drug (only use if nothing else worked)
- block fast sodium channels especially His-Purinje tissue
- No effect on APD
- No ANS effect
Flecainide
Class 1C
Limited use becase of its proarrhthymic effects leading to sudden cardiac death
Last ditch drug … some will be saved but many may die too
Flecainide, Propafenone
Class II
Beta blockers (see ANS)
- decrease SA and AV nodal activity (parasymp dominance)
- decrease slope of phase 4
Class II Drugs
Beta blockers Non selective (propranolol) and selective (acebutolol, esmolol)
Class II Uses
Beta blockers
- negative inotropic effect decreases O2 demand so helpful to reduce reccurence of MI or prevent MI in general
- Prophylaxis post MI, supraventricular tachyarrhythmias (SVT)
- Esmolol (IV) is used in acute SVTs