Pharm 23 - Anti-Arrhythmics Flashcards by Heather Wobbe

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

How well did you know this?

Not at all

Perfectly

Class IA Drugs (3)

Quinidine, Procainamide, Disopyramide

How well did you know this?

Not at all

Perfectly

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

Quinidine

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

Procainamide

How well did you know this?

Not at all

Perfectly

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

Disopyramide

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

Disopyramide

How well did you know this?

Not at all

Perfectly

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

Class IB

How well did you know this?

Not at all

Perfectly

Class IB Drugs (3)

Lidocaine, Mexiletine (oral analog of lidocaine), Phenytoin

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

Phenytoin

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

Class IC

How well did you know this?

Not at all

Perfectly

Class IC Drugs (4)

Encainide; Flecainide; Moricizine; Propafenone

How well did you know this?

Not at all

Perfectly

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

Class IC

How well did you know this?

Not at all

Perfectly

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

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

Class IC

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

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

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

Class III

Class III Drugs (6 random multi-syllable words)

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

Clinical applications Conversion of atrial fibrillation/flutter, maintenance of normal sinus rhythm afterwards

Ibutilide/Dofetilide

Adverse effects AV block, brady cardia, SVT, torsades de points

Ibutilide/Dofetilide

Contraindications Hx of polymorphic ventricular tachycardia (torsades de points), Preexisting long QT syndrome, creatinine clearance < 20mL/min

Ibutilide/Dofetilide

Therapeutic considerations May increase potential for prolonged refractoriness; drugs that prolong QT (antihistamines, phenothiazines, TCAs) increase risk of arrhythmia; Monitor QT interval

Ibutilide

Therapeutic considerations Reserved for pts w/ very symptomatic atrial fibrillation/flutter b/c of risk of ventricular arrhythmia; reduce dose in pts w/ renal dysfunction

Dofetilide

Clinical applications Life-threatening ventricular arrhythmias; maintenance of normal sinus rhythm in symptomatic atrial fibrillation/flutter

Sotalol

Adverse effects Bradycardia, torsades de points, PVCs, ventricular fibrillation/tachycardia, AV block, heart failure, bronchospasm; also dyspnea, chest pain, fatigue

Sotalol

Contraindications Severe SA dysfunction, sinus bradycardia, 2nd/3rd degree AV block, long QT syndrome, cardiogenic shock, heart failure, ASTHMA

Sotalol

Therapeutic considerations Mixed Class II/III agent; Used for pts that can't tolerate amiodarone; use w/caution in renal failure and DM; avoid coadministration with ziprasidone and sparfloxacin b/c of risk of prolonged QT interval

Sotalol

Clinical applications Life-threatening ventricular arrhythmias

Bretylium

Adverse effects Arrhythmia; also orthostatic hypotension, bradycardia, dizziness, anxiety, increased body temp.

Bretylium

Bretylium contraindications

Digitalis-induced arrhythmias

Bretylium therapeutic considerations

Also works as an antihypertensive agent

Clinical applications Recurrent ventricular fibrillation, unstable ventricular tachycardia, atrial fibrillation, supraventricular arrhythmia

Amiodarone

Adverse effects Arrhythmias, asystole, bradycardia, heart block, heart failure, hypotension, sinus arrest neutropenia, pancytopenia, hepatic failure, pulmonary toxicity (pneumonitis, alveolitis, fibrosis), thyroid dysfunction; also fatigue, corneal micro-deposits, photosensitivity, BLUE-GRAY SKIN PIGMENTATIONS

Amiodarone

Contraindications Pts taking ritonavir, severe SA-node disease, 2nd/3rd degree AV block, bradycardia w/ syncope

Amiodarone

Therapeutic considerations IV form causes "gasping syndrome" (gasping respiration/cardiovascular collapse) in neonates; Coadministration w/ beta blockers increases risk of sinus bradycardia/arrest and AV block; Coadministration w/ cholestyramine increases amiodarone elimination; Coadministration with cyclosporine, digoxin, flecainide, lidocaine, phenytoin, procainamide, quinidine, or theophyline increases amiodarone levels; Coadministration w/ drugs that prolong QT interval (disopyramide, thioridazine, quinidine, TCA) increase risk of prolonged QT/torsades de pointes; Coadministration w/ phenytoin can decrease amiodarone levels (do not ask why - I don't understand it either...)

Amiodarone

Dronederone clinical applications

Atrial fibrillation/flutter

Adverse effects Heart failure, hepatic failure; also prolonged QT interval, abdominal pain, D, indigestion, asthenia, elevated serum creatinine (does not affect GFR)

Dronederone

Contraindications Bradycardia, prolonged QT/PR, AV block, heart failure, hepatic impairment, PREGNANCY, use of QT-prolonging drugs, use of CYP3a inhibitors

Dronederone

Therapeutic considerations Similar to amiodarone but less thyroid toxicity and shorter T1/2

Dronederone

MOA Calcium Channel Blockers: preferentially block cardiac Ca2+ channels; slow action potential upstroke in SA and AV nodes; SEE PHARM 21

Class IV

MOA Opens G protein-coupled K+ channel and suppresses Ca2+ dependent action potential -> inhibits SA/AV/atrial conduction

Adenosine

Adenosine clinical applications

Conversion of paroxysmal SVT

Adverse effects Facial flushing, bronchoconstriction (in pts w/asthma), chest pressure, diaphoresis, excessive SA/AV node inhibition

Adenosine

Contraindications 2nd/3rd degree AV block, atrial fibrillation/flutter

Adenosine

Therapeutic considerations Coadministration w/ carbamazepine may increase degree of heart block; may cause transient arrhythmia when first administered

Adenosine

Ranolazine clinical applications

Chronic angina

Adverse effects Prolonged QT interval, syncope, acute renal dysfunction; also D/C, HA

Ranolazine

Contraindications Use of QT-prolonging drugs, preexisting prolonged QT, use of CYP 3A inhibitors, hepatic dysfunction

Ranolazine

Therapeutic considerations Use in combination w/ beta blockers, amlodipine, or nitrates if needed; avoid use in pts w/ severe renal impairment

Ranolazine