Type Ia Anti-Arrhythmic Drugs

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Questions and Answers

What is the indication for using a pacemaker in patients?

Unresponsive to sodium bicarbonate therapy (correct)

Ventricular arrhythmias

Supraventricular rhythm disorders

Unresponsive to quinidine therapy

What is a side effect of disopyramide?

Tachycardia

Urinary retention (correct)

Increased heart rate

Hypotension

Which of the following is NOT a method of enhanced elimination for quinidine?

Activated charcoal

Acidification of urine (correct)

Dialysis

Hemoperfusion

Which anti-dysrhythmic drug has alpha-adrenergic receptor-blocking activity?

Quinidine Signup and view all the answers

What type of arrhythmias do quinidine and procainamide suppress?

Supraventricular arrhythmias Signup and view all the answers

Which of the following is a clinical presentation of anti-dysrhythmic overdose?

Sedation Signup and view all the answers

What is the class of anti-dysrhythmic drugs that includes Tocainide, Mexiletine, and Lidocaine?

Class Ib Signup and view all the answers

What is the effect of disopyramide on the heart rate?

Decreases heart rate Signup and view all the answers

Which of the following is a method of decontamination for anti-dysrhythmic overdose?

Activated charcoal Signup and view all the answers

What is the primary mechanism of toxicity for the drugs mentioned?

Dilation of peripheral arterioles Signup and view all the answers

What is the effect of Reflex sympathetic response on the heart?

Tachycardia and arrhythmias Signup and view all the answers

What is the excretion route for 60% of Prazosin and other newer α1 specific agents?

Fecal excretion Signup and view all the answers

What is the purpose of repeat-dose activated charcoal in the treatment of toxicity?

To enhance elimination of the drug Signup and view all the answers

Which laboratory studies are recommended in the treatment of toxicity?

Electrolytes, glucose, and ECG Signup and view all the answers

What is the primary goal of emergency and supportive measures in the treatment of toxicity?

To reduce the severity of symptoms Signup and view all the answers

Which of the following drugs is not associated with specific blood levels that are routinely available or clinically useful?

Indoramin Signup and view all the answers

What is the effect of Terazosin and doxazosin on the body?

They are long-acting and eliminated slowly Signup and view all the answers

What is the purpose of decontamination measures such as activated charcoal, ipecac-induced emesis, and cathartics in the treatment of toxicity?

To reduce absorption of the drug Signup and view all the answers

Which of these drugs is NOT a Type Ia antiarrhythmic?

Amiodarone Signup and view all the answers

What is the primary mechanism of action for Type Ia antiarrhythmics?

Depressing fast sodium-dependent channels Signup and view all the answers

What is a potential side effect of prolonged use of procainamide?

Lupus-like syndrome Signup and view all the answers

Which of the following is a characteristic of the prolonged QT interval that can occur with Type Ia antiarrhythmics?

Rapid, irregular heartbeat originating from the ventricles Signup and view all the answers

Which of the following is a potential adverse effect of Type Ia antiarrhythmics related to myocardial contractility?

Decreased myocardial contractility Signup and view all the answers

Which of the following is NOT a typical treatment for Type Ia antiarrhythmic overdose?

Beta-blockers Signup and view all the answers

How do Type Ia antiarrhythmics affect the cardiac action potential?

They shorten phase zero of the cardiac action potential Signup and view all the answers

What is the relationship between the prolonged QT interval and polymorphic ventricular tachycardia?

A prolonged QT interval is a cause of polymorphic ventricular tachycardia Signup and view all the answers

Which of these drugs can cause lupus-like syndrome?

Procainamide Signup and view all the answers

What is the primary cause of hyperglycemia in calcium channel blocker toxicity?

Decreased free fatty acid utilization Signup and view all the answers

What is the term for the condition characterized by an accumulation of lactic acid in the blood?

Metabolic acidosis Signup and view all the answers

Which laboratory test is used to confirm the presence of lactic acidosis?

ABG analysis Signup and view all the answers

What medication is used to treat hemodynamically significant bradycardia in calcium channel blocker toxicity?

Atropine Signup and view all the answers

Which of these is a potential complication of calcium channel blocker toxicity?

Depressed cardiac contractility Signup and view all the answers

What is the recommended dose of IV calcium gluconate for calcium channel blocker toxicity?

2-4 g Signup and view all the answers

What medication is used to improve heart rate and contractility in calcium channel blocker toxicity?

Mid-dose dopamine Signup and view all the answers

Which of these medications can be used as an alternative to dopamine or norepinephrine if a long transport time is likely?

Glucagon Signup and view all the answers

What is the primary reason for administering activated charcoal in calcium channel blocker toxicity?

To absorb the toxin Signup and view all the answers

Study Notes

Type Ia Antiarrhythmics

Depressed myocardial contractility associated with alpha-adrenergic blockade may lead to hypotension and potential pulmonary edema.
Examples include Quinidine, Procainamide (Pronestyl®), and Disopyramide (Norpace®).
Mechanism of action involves depressing fast sodium-dependent channels, slowing phase zero of cardiac action potential.
High concentrations can severely reduce myocardial contractility and depress cardiac conduction velocity.
Common side effects of Procainamide include gastrointestinal upset and a lupus-like syndrome characterized by a butterfly rash from chronic use.
Reduced myocardial contractility results in inhibited Na channels and prolonged QT interval, potentially leading to polymorphic ventricular tachycardia.
A cardiac pacemaker may be required if patients do not respond to sodium bicarbonate therapy.
Quinidine and Disopyramide possess anticholinergic properties, leading to urinary retention, constipation, and dry mouth.
Effective for managing acute and chronic supraventricular and ventricular arrhythmias.
Treatment strategies include emergency support measures, activated charcoal for decontamination, and enhanced elimination methods like dialysis.

Type Ib Antiarrhythmics

Includes drugs like Tocainide, Mexiletine, and Lidocaine.
Clinical presentations may show sedation and effects on cardiovascular performance.
Laboratory studies to monitor involve electrolytes, blood glucose, BUN, creatinine, and ECG analysis.

Mechanism of Toxicity (Type Ib)

Peripheral vasodilation can lead to hypotension.
Negative effects include negative chronotropy, inotropy, and dromotropy, which can slow heart rate and conduction.
Reflex sympathetic response can induce tachycardia and arrhythmias.

Cardiovascular Effects of Calcium Channel Blockers

Hypotension treatment involves fluid boluses; if ineffective, dopamine or norepinephrine may be considered.
Prolonged CPR is indicated in cases of cardiac arrest from calcium channel blocker overdose as patients can remain neurologically intact after extended resuscitation efforts.

Laboratory Studies in Toxicity Management

Assess serum electrolytes and renal function (BUN/creatinine) for optimum treatment response.
Administer IV calcium gluconate/chloride and glucagon if hypotension persists.
Activated charcoal is safe if the airway is protected, but avoid ipecac syrup.

General Treatment Approaches

Immediate supportive measures essential during toxic exposure.
Regular monitoring of vital signs and ECG is critical during treatment of antiarrhythmic and overdose scenarios.

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Description

This quiz covers the effects and mechanisms of Type Ia anti-arrhythmic drugs, including quinidine, procainamide, and disopyramide. Learn about their impact on myocardial contractility and potential side effects.