Anti-dysrhythmics Flashcards
What is the mechanism of action of the Class I anti-dysrhythmic drugs?
Block voltage-sensitive sodium channels
What is the mechanism of action of the Class II anti-dysrhythmic drugs?
Beta adrenoreceptor antagonists
What is the mechanism of action of the Class III anti-dysrhythmic drugs?
Prolong the refractory period of the myocardium, suppress re-entrant rhythms.
What is the mechanism of action of the Class IV anti-dysrhythmic drugs?
Calcium antagonists - impair impulse propagation in damaged areas of the myocardium.
Class I drugs bind most strongly when Na+ channels are in the ____ or ____ state.
Open or refractory
Class I drugs are _____ dependent.
Frequency
Class I drugs work better at (high or low) frequencies?
High
Which drug is a Class Ib anti-dysrhthmic?
Lidocaine
For what type of condition would a Class Ib be used?
Ventricular dysrhythmia following myocardial infarction
Which drug is a Class Ic anti-dysrhythmic?
Flecainide
For what are Class Ic drugs used?
General reduction of excitation (dampen excitability of the heart)
Which two drugs are Class Ia anti-dysrhythmics?
- Quinidine
2. Procainamide
Place the following in order of slowest to faster to associate and dissociate: Class Ia, Class Ib, Class Ic.
Class Ic
Beta-1 receptors on the heart increase ____ ____ and ____.
Beta-1 receptors on the heart increase HEART RATE and EXCITABILITY.
Which drug is used as an example of the Class III anti-dysrhythmics?
Amiodarone
What are the two drugs used as examples for the Class IV anti-dysrhythmics?
- Verapamil
2. Diltiazem
For what is Quinidine used in the horse?
Atrial fibrillation (prolongs the atrial refractory period)
What are the main indications for the use of Quinidine?
Atrial and ventricular dysrhythmias (tachycardias)
What is the contraindication for the use of Quinidine?
Hepatic insufficiency
What are the side effects associated with Quinidine? (There are 7)
- Anorexia
- Diarrhea
- Vomiting
- Ventricular fibrillation
- Tachycardia
- Ataxia
- Allergic reaction
How is Quinidine administered?
Orally
Procainamide is often preferred in the dog for maintenance of ____ ____ or ____ ____.
Procainamide is often preferred in the dog for maintenance of VENTRICULAR ARRHYTHMIAS or VENTRICULAR TACHYCARDIAS.
Procainamide is contraindicated in _____ _____.
Procainamide is contraindicated in CONDUCTION BLOCK.
What are the contraindications for the use of Lidocaine (Class Ib)?
- Atrial fibrillation
2. Atrial flutter
What are the side effects of Lidocaine (Class Ib)?
- Seizure
2. Hypotension
Which drug is NOT effective in the presence of hypokalemia?
Lidocaine
