Pharm 23 - Anti-Arrhythmics Flashcards Preview

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Flashcards in Pharm 23 - Anti-Arrhythmics Deck (61)
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1

MOA Moderate block of voltage-gated Na+ channels; block K+ channels in ventricular myocytes (decreased phase 0 upstroke velocity, prolongs depolarization) and SA nodal cells (shifts threshold to more positive potentials and decreases slope of phase 4 depolarization)

Class IA

2

Class IA Drugs (3)

Quinidine, Procainamide, Disopyramide

3

Also Blocks K+ channels that are opened upon vagal stimulation of muscarinic receptors in the AV node (vagolytic effect)

Quinidine

4

Clinical applications Conversion of atrial flutter/fibrillation; maintenance of normal sinus rhythm; paroxysmal SVT; Premature atrial/ventricular contractions; paroxysmal AV junctional rhythm or atrial/ventricular tachycardia

Quinidine

5

Clinical applications Symptomatic premature ventricular contractions (PVCs); life-threatening ventricular tachycardia; maintenance of normal sinus rhythm after conversion of atrial flutter; MALIGNANT HYPERTHERMIA

Procainamide

6

Clinical applications PVCs; Ventricular tachycardia; Conversion of atrial fibrillation/flutter and paroxysmal atrial tachycardia to normal sinus rhythm

Disopyramide

7

Adverse effects Torsades de pointes ( & syncope w/ quinidine), complete AV block, ventricular tachycardia, agranulocytosis, thrombocytopenia, hepatotoxicity, acute asthma attack, respiratory arrest, angioedema, SLE; also fatigue, headache, lightheadedness, widening of QRS, lengthening of QT and PR, hypotension, PVCs, tachycardia, diarrhea, cinchonism (More SLE and less anticholinergic w/ Procainamide; More anticholinergic and less GI w/ Disopyramide)

Class IA

8

Contraindications Hx of torsades de points, Hx of prolonged QT interval, concurrent use of drugs that prolong QT interval (thioridazine, ziprasidone), Conduction defects, Myasthenia gravis; also SLE for Procainamide

Class IA

9

Therapeutic considerations - Inhibits conversion of codeine to morphine -> reduced analgesic effect
- Digoxin toxicity
- Amiodarone, amprenavir, azole antifungals, cimetidine, and ritonavir increase quinidine levels
- Avoid co-administration with anticholinergics b/c increases anticholinergic effects
- Agent that slows AV conduction (beta blocker/CCB) should be used w/ quinidine in pts w/ atrial flutter to prevent too rapid ventricular response

Quinidine

10

Therapeutic considerations - Does not alter plasma levels of digoxin
- Consider pre-treatment w/ cardiac glycoside to prevent accelerated ventricular rate due to vagolytic effects on AV node
- Take baseline ANA and monitor during therapy for development of lupus-like syndrome

Procainamide

11

Therapeutic considerations - Rifampins impair efficacy
- Consider pre-treatment w/ cardiac glycoside to prevent accelerated ventricular rate due to vagolytic effects on AV node

Disopyramide

12

MOA Use-dependent block of voltage gated Na+ channels in ventricular myocytes (decreased phase 0 upstroke velocity), may shorten REpolarization

Class IB

13

Class IB Drugs (3)

Lidocaine, Mexiletine (oral analog of lidocaine), Phenytoin

14

Clinical applications Ventricular arrhythmias when they occur w/ MI, cardiac manipulation, or cardiac glycosides; status epilepticus; Local anesthesia of skin/mucus membranes; pain, burning, itching; Postherpetic neuralgia

Lidocaine/Mexiletine

15

Adverse effects Seizures, asystole/cardiac arrest, new/worse arrhythmias, bradycardia, respiratory depression, anaphylaxis, status asthmaticus; also restlessness, stupor, tremor, hypotension, diplopia/blurred vision, tinnitus

Lidocaine/Mexiletine

16

Contraindications Stokes-Adams syndrome; Wolff-Parkinson-White syndrome; severe conduction blocks; don't give spinal/epidural block w/ inflammation, infection, septicemia, severe HTN, spinal deformities, neuro disorders

Lidocaine/Mexiletine

17

Dose adjustment if coadministered w/ CYP450 inhibitors (cimetidine) or inducers (barbiturates, phenytoin, rifampin); In severely-ill pts, seizures are 1st sign of toxicity; IM injection of lidocaine can greatly increase serum CK

Lidocaine/Mexiletine

18

Clinical applications Generalized tonic-clonic seizures, status epilepticus, non-epileptic seizures, eclampsia seizures; Neuralgia, Ventricular arrhythmias that don't respond to lidocaine/procainamide, Arrhythmias induced by cardiac glycosides

Phenytoin

19

Adverse effects Agranulocytosis, leukopenia, pancytopenia, thrombocytopenia, hepatitis, Stevens-Johnson syndrome, TOXIC EPIDERMAL NECROLYSIS; also ataxia, confusion, slurred speech, diplopia, nystagmus, gingival hyperplasia, hirsutism, N/V

Phenytoin

20

Contraindications Hydantoin (whatever THAT is) hypersensitivity, Sinus bradycardia, SA block, 2nd/3rd degree AV block, Stokes-Adams syndrom

Phenytoin

21

Therapeutic considerations Metabolized by P450 2C9/10 and 2C19 - coadministration w/ other drugs metabolized by same enzymes can increase plasma phenytoin; Can induce P450 3A4 - increased metabolism of oral contraceptives, etc.

Phenytoin

22

MOA Block of voltage gated Na+ channels in ventricular myocytes (decreased phase 0 upstroke velocity)

Class IC

23

Class IC Drugs (4)

Encainide; Flecainide; Moricizine; Propafenone

24

Clinical applications Last resort-type drug for sustained ventricular tachycardia, paroxysmal SVT, and paroxysmal atrial fibrillation

Class IC

25

Adverse effects Cardiac arrest, heart failure, new/worsened arrhythmia (especially in pts with atrial fibrillation/flutter), SA dysfunction, decreased conduction velocity, conduction block; also - if you survive all that - dizziness, headache, syncope, dyspnea, visual disturbances

Class IC

26

Contraindications Cardiogenic shock, 2nd/3rd degree AV block, RBBB w/ left hemi-block

Class IC

27

Therapeutic considerations Only use in pts who have failed other measures; may suppress ventricular escape rhythms; monitor levels in pts w/ hepatic impairment

Class IC

28

MOA Beta-blockers; antagonize stimulation of Beta1-adrenergic receptors in SA/AV nodes -> decrease slope of phase 4 depolarization (SA node) and prolonging repolarization (AV node); SEE PHARM 10

Class II

29

MOA Block K+ channels, prolonging action potential plateau and repolarization

Class III

30

Class III Drugs (6 random multi-syllable words)

Ibutilide; Dofetilide (oral only); Sotalol; Bretylium; Amiodarone; Dronederone