AntiArrhythmatic drugs

Question 1

Class I

Answer 1

Na channel blockers

Question 2

Class II

Answer 2

Beta blockers

Question 3

Class III

Answer 3

K channel blockers

Question 4

Class IV

Answer 4

Ca channel blockers

Question 5

Procainamide

Answer 5

Class IA Slows upstroke of AP, slows conduction, prolongs QRS by non-specific blockade of K channels. used for atrial and ventric arrhythmias. Avoid long term therapy.

AE: Excessive AP and QT prolongation, induces torsades de pointes, and Lupus sx.

PK:
Used in WPW

Question 6

Quinidine

Answer 6

Class IA, Class IA Slows upstroke of AP, slows conduction, prolongs QRS by non-specific blockade of K channels antimuscarinic effects. Rarely used due to effects

AE: diarrhea N&V, torsades de pointes arrhythmia and syncope.

PK: GI abs, hep met.

Question 7

Disopyramide

Answer 7

Class IA, Slows upstroke of AP, slows conduction, prolongs QRS by non-specific blockade of K channels antimuscarinic effects. Tx ventricular arrhythmias

AE: atropine like effects, may precipitate heart failure,

PK: hepatic met

Question 8

Lidocaine

Answer 8

Class IB, Selective depression of conduction in depolarized cells, little effect on ECG. Drug of choice for temination of V-tach and prevention of V fib after cardioversion. Least side effects.

AE: Least, paresthesias, tremor, nausea, slurred speech, convulsions

PK: Extensive first pass, give parenterally

Question 9

Mexiletine

Answer 9

Class IB. Orally active Lidocaine. elective depression of conduction in depolarized cells, little effect on ECG. Drug of choice for ventricular arrhythmias. Least side effects.

AE: Significant chronic pain reduction due to diabetic neuropathy and nerve injury. Tremor, blurred vision, lethargy.

PK: Hepatic met, longer half life than lidocaine

Question 10

Tocainide

Answer 10

Not sold in USA
Class IB, lidocaine analog.elective depression of conduction in depolarized cells, little effect on ECG. Drug of choice for ventricular arrhythmias. Least side effects.

AE: Significant chronic pain reduction due to diabetic neuropathy and nerve injury. Tremor, blurred vision, lethargy.

PK:glucuronidation met, longer half life than lidocaine

Question 11

Flecainide

Answer 11

Class IC, slows upstroke of AP, slows conduction, Potent Na and K channel blocker, slow unblocking kinetics, no AP or QT interval prolonging.
Tx. supraventricular arrhythmias.

AE: makes arhytmia worse when pt has tachyarrhythmias and prior MI and ventricular ectopy

PK: hepatic and renal

Question 12

Propafenone

Answer 12

Class IC, slows upstroke of AP, slows conduction, Weak B blocker. used for supraventricular arrhythmias. does not prolong AP.

AE: metallic taste, constipation, arrhythmia exacerbation.

PK: hepatic

Question 13

Moricizine

Answer 13

Not sold in US.
Class IC, slows upstroke of AP, slows conduction, does not prolong AP duration.
Used for ventricular arrhythmias.

AE:

PK: Extensive 1st pass metab.

Question 14

Propranolol

Answer 14

B blocker (class II) Inhibits sympathetic activity on B1 receptor. Sloppy.

AE: bronchospasm, bradycardia, fatigue

PK: Extensive 1st pass met.

Question 15

Acebutolol

Answer 15

B blocker (class II), Cardioselective B blocker, better for patients with asthma.

AE: fatigue

PK: 1st pass metabolism, feces.

Question 16

Esmolol

Answer 16

B blocker (class II), Short acting , used primarily for intraoperative and acute arrhythmias

AE: mild

PK: Metabolized by RBC esterases.

Question 17

Sotalol

Answer 17

B blocker (class II), nonselective B blockers, prolongs the action potential by slowing outward current of K.

AE: Bronchoconstriction, bradycardia, fatigue

PK: 100% bioavailability, excreted unchanged

Question 18

Class IA

Answer 18

Na Fast channel blockers, widens QRS, used for a-fib, flutter, super ventricular and ventricular tachyarrhythmias.

Question 19

Class IB

Answer 19

Weak Na channel blockade, does not affect QRS, shortens AP and refractory period. Used for ventricular tachyarrhythmias.

Question 20

Class IC

Answer 20

Strongest Na channel blockade, no effect on AP length, shorter QRS. Used for super ventricular tachyarrhythmias, and ventricular tachyarrhythmias.

Question 21

Class II Drugs

Answer 21

B blockers, prevent sympathetic innervation of the heart.

Question 22

Class III Drugs

Answer 22

K channel blockers, Prolong repolarization, lengthening the QT interval. Prevents reentry arrythmias are considered pro arrhythmic as well as anti arrhythmic.

Question 23

Class IV drugs

Answer 23

Blocks L- type Calcium channel blockers on smooth muscle, cardiac myocytes, and SA/ AV nodes. Causes vasodilation, decreased myocardial contractility. Shortened phase 2 of AP in myocytes and lessened force of contraction. In Nodal cells, blocks Ca entry leading to slowed HR, Decreased conduction velocity. Used for angina, block reentry,

Question 24

Class V drugs

Answer 24

Misc drugs

Question 25

Amiodarone

Answer 25

Class III,(also a poor Class1,2,4 drug) prolongs AP by K channel blockade used for ventricular tach, and v fib, a fib.

AE: Dose related pulmonary tox. eye probs. Bradycardia of nodal disease, drug accumulation in tissues, blocks production of T3

PK: Hepatic CYP3A4, drug interactions

Question 26

Dofetilide

Answer 26

Class III, selective K blocker, prolongs AP, prolonged QT from long refractory . in His-purkinje system and ventricles.
A-fib, not for long Qt, bradycardia, hypokalemia

AE: Ventricular arrythmias

PK: 100% bioavailable, CYP3A4

Question 27

Ibutilide

Answer 27

Class III, prolongs AP, also slows inward Na activator, which delays repolarization, inhibits Na channel inactivation increasing ERP. Used for A-fib and more flutter.

AE: Q-T prolongation and torsades de pointes, v arrhythmias.

PK: hepatic

Question 28

Class IV Dihydropurines

Answer 28

Smooth muscle selective class IV, used to reduce systemic resistance and treat hypertension, not generally used for angina. All end in -pined

Question 29

Class IV Non-dihydropurines

Answer 29

Block Ca channels selectively for myocardium, Treat angina, are verapamil, diltiazem

Question 30

Verapamil

Answer 30

Class IV Blocks activated and inactivated L-type Ca channels, treats supra ventricular tachycardia, a-fib and flutter.

AE: bradycardia peripheral vasodilation. contraindicated in Wolff-P-W, Can cause AV block, constipation, edema.

PK: hepatic

Question 31

Diltiazem

Answer 31

Class IV Blocks activated and inactivated L-type Ca channels, treats supra ventricular tachycardia, a-fib and flutter.

AE: peripheral vasodilation. contraindicated in Wolff-P-W, Can cause AV block, constipation, edema.

PK: hepatic

Question 32

Digoxin

Answer 32

Inhibits Na K ATPase which reverses action on Na/Ca exchanger leading to more Ca in cell and inproved cardiac contractility.
Also activates vagal efferents on heart slowing SA rate and AV conduction increasing refractory period
used for a fib and flutter, heart failure. reduces ventricular rate when driven by a high atrial rate.

AE: Extreme AV block, not for AV block patients, WPW, drug interactions

PK: kidney excretion
‘Toxicity= GI distress, hyperkalemia, arrhythmias, av nodal blockade

Question 33

Adenosine

Answer 33

Activates inward rectifier K channels, inhibits L-type Ca channels. Results in hyperpolarization and suppression of Ca dependent AP.

Drug of choice for paroxysmal supra ventricular tachycardia.

Used therapeutically for SVT.

AE: vasodillation leading to hypotension, flushing, headache, AV block

PK: methyxanthines (caffeine) are competitive antagonizers.