Antiarrhythmics: Difference between revisions

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==Lidocaine==
==Table==
=== Adult Dosing ===


*Loading dose = 1-1.5 mg/kg
{| class="wikitable" style="width: 641px; height: 711px;"
**Additional boluses of 0.5-0.75 mg/kg q5-10min up to max of 3mg/kg
|-
**If effective start infusion of 2mg/min
! Class
! Known as
! Examples
! Mechanism
! Clinical uses
|-
! Ia
| fast-channel blockers-Affect QRS complex
|
*Quinidine
*[[Procainamide]]
*Disopyramide


=== Contraindications ===
| (Na<sup>+</sup>) channel block (intermediate association/dissociation)
|
*Ventricular arrhythmias
*prevention of paroxysmal Recurrent atrial fibrillation (triggered by Vagus nerve overactivity)
*procainamide in [[Wolf Parkinson White (WPW)]]


*High SA or AV block
|-
! Ib- Do not affect QRS complex
|
|
*[[Lidocaine]]
*Phenytoin
*Mexiletine
*Tocainide


=== Indications ===
| (Na<sup>+</sup>) channel block (fast association/dissociation)
|
*treatment and prevention during and immediately after Myocardial infarction, though this practice is now discouraged given the increased risk of Asystole
*Ventricular tachycardia
*[[Atrial Fibrillation (Main)|Atrial fibrillation]]


*Treatment of ventricular arrhythmias and ectopy
|-
**Considered 2nd-line to amiodarone for tx of V-fib and pulseless v-tach
! Ic
|
|
*[[Flecainide]]
*Propafenone
*Moricizine


=== Mechanism of Action ===
| (Na<sup>+</sup>) channel block (slow association/dissociation)
|
*prevents Paroxysmal atrial fibrillation
*treats Recurrent tachyarrhythmias of abnormal conduction system.
*contraindicated immediately post-myocardial infarction.


*Class Ib
|-
**Binds to fast Na channels in inactive state thereby inhibiting recovery after repolarization
! II
**Acts preferentially on ischemic tissue
| [[Beta-blockers]]
***Elevates V-fib threshold
|
***Suppresses ventricular ectopy
*Propranolol
*Little effect on vascular tone, contractility or cardiac output
*[[Esmolol]]
*Timolol
*[[Metoprolol]]
*[[Atenolol]]
*Bisoprolol
*[[Labetalol]]


=== Adverse Drug Rxns ===
| beta blocking<br>Propranolol also shows some class I action
|
*decrease Myocardial infarction mortality
*prevent recurrence of Tachyarrhythmias


*CNS
|-
**Abrupt change in MS, drowsiness, confusion, sz
! III
|
|
*[[Amiodarone]]
*[[Sotalol]]
*[[Ibutilide]]
*Dofetilide
*Dronedarone
*E-4031


=== Kinetics ===
|
K<sup>+</sup> channel blocker


*Onset of action = 45-90s
Sotalol is also a β-blocker
*Duration of action = 10-20min


== Procainamide ==
Amiodarone has Class I, II, and III activity


=== Adult Dosing ===
|
*In [[Wolf Parkinson White (WPW)]]
*(sotalol:) Ventricular tachycardias and Atrial fibrillation
*(Ibutilide:) Atrial flutter and [[Atrial Fibrillation (Main)|Atrial fibrillation]]


*Continuous infusion rate has fewer adverse effects
|-
**20-50mg/min for 25-30min
! IV
***Cont until arrhythmia is suppressed, hypotension, QRS >50% or max dose (17mg/kg)
| slow-channel blockers
***If effective start cont infusion of 1-4mg/min
|
*Verapamil
*[[Diltiazem]]


=== Contraindications ===
| Ca<sup>2+</sup> channel blocker
|
*prevent recurrence of Paroxysmal supraventricular tachycardia
*reduce Ventricular rate in patients with [[Atrial Fibrillation (Main)|Atrial fibrillation]]


*Not recommended for V-fib or pulseless V-tach (too long to dose)
|-
*2nd or 3rd AV block
! V  
*Severe glycoside intoxication
|
*Prolonged QT
|
*Myasthenia gravis
*[[Adenosine]]
*[[Digoxin]]
*[[Magnesium sulfate]]


=== Indications ===
| Work by other or unknown mechanisms (Direct nodal inhibition).
|
Used in supraventricular arrhythmias,


*Wide-complex tachycardia of unknown type (in pts w/ preserved LV function)
Or in the case of [[magnesium sulfate]], used in [[torsade de pointes]].
*Stable V-tach


=== Mechanism of Action ===
|}


*Class Ia
==See Also==
**Binds to fast Na channels in inactive state thereby inhibiting recovery after repolarization
*[[Arrhythmias (DDX)]]
**Prolongs action potential and reduces speed of impulse conduction
*[[Atropine]]
***Depresses myocardial conduction
*[[Isoproterenol]]
**May act as negative inotrope, cause hypotension (peripheral vasodilation)


=== Adverse Drug Rxns ===
==References==
<references/>
*Katzung &amp; Trevor's Pharmacology


*Myocardial depression
[[Category:Pharmacology]] [[Category:Cardiology]]
*Watch for QRS/QT prolongation, V-tach, Vfib, complete AV block, torsades
 
=== Kinetics ===
 
*Onset of action = 5-10min
 
== Esmolol ==
 
=== Adult Dosing ===
 
*Loading dose = 500mcg/kg bolus over 1min
**Follow this w/ infusion at 50mcg/kg/min for 4min
***If no response give another 500 bolus, incr infusion to 100
***If no response give another 500 bolus, incr infusion to 200
 
=== Contraindications ===
 
*Cardiogenic shock
*2nd or 3rd AV block
 
=== Indications ===
 
*Supraventricular arrhythmias
 
=== Mechanism of Action ===
 
*Class II - Short-acting Beta1 blocker
 
=== Adverse Drug Rxns ===
 
*Hypotension
*Bronchospasm
 
=== Kinetics ===
 
Onset of action = 1-4min Duration of action = <30min
 
== Labetalol ==
 
=== Adult Dosing ===
 
*Bolus dosing
**20mg IV followed by 40-80mg q10min up to total of 300mg
*Infusion dosing
**0.5-2mg/min
 
=== Indications ===
 
*HTN in setting of myocardial ischemia
*HTN in setting of neurologic injury
*HTN in setting of preeclampsia/eclampsia
 
=== Mechanism of Action ===
 
*Class II - Nonselective beta blocker
*Alpha1 blocker
 
=== Adverse Drug Rxns ===
 
*Orthostatic hypotension
 
=== Kinetics ===
 
*Onset of action = 2-5min (IV)
*Duration of action = 2-4hr (IV)
 
== Sotalol ==
 
=== Adult Dosing ===
 
*80mg PO BID
 
=== Indications ===
 
*Suppression of ventricular arrhythmias refractory to other meds
*Suppression of SVT, a-fib
 
=== Mechanism of Action ===
 
*Class II - Nonselective beta-blocker
*Class III effects (prolongs repol and refractoriness)
 
=== Adverse Drug Rxns ===
 
*Hypotension, bradycardia
*Proarrhythmia (esp in pts w/ hypokalemia)
 
=== Kinetics ===
 
*Onset of action = 2-3hr
*Duration of action = 24hr
 
== Amiodarone ==
 
=== Adult Dosing ===
 
*V-fib/pulseless V-tach
**Loading dose = 300mg IV bolus followed by 150mg bolus prn
*Stable V-tach or SVT
**Loading dose = 150mg IV in 100mL D5W over 10min
***Follow by infusion of 1mg/min x 6hr; 0.5mg/min thereafter
 
=== Contraindications ===
 
*Iodine or shellfish allergy
*Pregnancy
 
=== Indications ===
 
*Ventricular and supraventricular arrhythmias
*1st line for pulseless V-tach/V-fib
*Used for atrial arrhythmias in pts w/ decr EF
 
=== Mechanism of Action ===
 
*Class III - Inhibits potassium channels
**Impairs SA and AV node conduction
**Decreases automaticity
**Prolongs refractory period in accessory pathways
*Also has class I & II properties
 
=== Adverse Drug Rxns ===
 
*Bradycardia, hypotension
*Prolonged QT
 
== Ibutilide ==
 
=== Adult Dosing ===
 
*Loading dose = 1mg IV in 50mL D5W over 10min (wt>60kg)
*Loading dose = 0.01mg/kg IV in 50mL D5W over 10min (wt<60kg)
*Dose may be repeated 10min after completion of 1st dose
 
=== Contraindications ===
 
=== Indications ===
 
*Rapid conversion of recent-onset A-fib/flutter to NSR
 
=== Mechanism of Action ===
 
*Class III - Prolongs AP and refractory period
 
=== Adverse Drug Rxns ===
 
*QT prolongation, V-tach, torsades
*Observe for 4hr after infusion
 
=== Kinetics ===
 
*Onset of action = 20-30min
*Duration of action = 24hr
 
== Diltiazem ==
 
=== Adult Dosing ===
 
*Loading dose = 0.25mg/kg (max=20mg) IV bolus over 2min
**If ineffective after 15min: 0.35mg/g (max=25mg) over 2min
**If effective: Start infusion at 5-15mg/hr
 
=== Contraindications ===
 
*Wide-complex tachycardia due to bypass tract
 
=== Indications ===
 
*Conversion of PSVT to NSR
*Slow RVR in a-fib/flutter
 
=== Mechanism of Action ===
 
*Class IV - Inhibits Ca influx
**Slows AV nodal conduction
 
=== Adverse Drug Rxns ===
 
Bradycardia, CHF, AV block, BBB, hypotension
 
=== Kinetics ===
 
*Onset of action = 2-3min (IV)
*Duration of action = 1-3hr (IV)
 
== Atropine ==
 
=== Adult Dosing ===
 
*Loading dose = 0.5mg rapid IV bolus q3-5min (max = 0.04 milligram/kg)
*May be given IM, IO, SC
 
=== Indications ===
 
*Symptomatic sinus or AV nodal bradycardia
 
=== Mechanism of Action ===
 
*Parasympatholytic
**Increases sinus/AV conduction
 
=== Adverse Drug Rxns ===
 
*Increased O2 consumption
*If given slowly (or <0.5mg) may lead to paradoxical bradycardia
 
=== Kinetics ===
 
*Onset of action = 2-4min
*Duration of action = 5hr
 
== Adenosine ==
 
=== Adult Dosing ===
 
*6mg rapid IV bolus over 1-2s
**If ineffective can try 12mg 2min later
***If still ineffective can try another 12mg
 
=== Contraindications ===
 
*2nd, 3rd AV block
*Sick sinus syndrome
*Reentrant SVTs not involving AV node are not terminated
*No effect on anterograde WPW
 
=== Indications ===
 
*Conversion of reentrant PSVT to NSR
 
=== Mechanism of Action ===
 
*Negative inotropic, dromotropic, chronotropic effects
*Transient AV nodal block
 
=== Adverse Drug Rxns ===
 
*Bronchoconstriction (responds to bronchodilators)
*Bradyarrhythmia
*Hypotension (if given too slowly)
 
=== Kinetics ===
 
Onset of action = 20-30s Duration of action = 60-90s
 
== Digoxin ==
 
=== Adult Dosing ===
 
*Loading dose = 0.25 mg IV q2hr until effect (max total = 1.5 mg
 
=== Contraindications ===
 
*WPW
**Increases conduction velocity in atrial tissue
 
=== Indications ===
 
*RVR control in a-fib/flutter, PSVT
 
=== Mechanism of Action ===
 
*Inhibits NaK pump
**Positive inotropy
*Negative chronotropy/dromotropy
**Indirect vagal stimulator
 
=== Adverse Drug Rxns ===
 
*GI - N/V, diarrhea, abd pain
*CV - Bradycardia, SA/AV block, ventr arrhythmias
 
=== Kinetics ===
 
Onset of action = 1.5-4hr (IV)
 
== Isoproterenol ==
 
=== Adult Dosing ===
 
2-10mcg/min IV by continuous infusion
 
=== Indications ===
 
*Refractory torsades
*Refractory symptomatic bradycardia
 
=== Mechanism of Action ===
 
*Beta agonist
 
=== Adverse Drug Rxns ===
 
*Dramatic increase in O2 demand
*V-tach (use lowest dose possible)
 
=== Kinetics ===
 
*Onset of action = 1-5min
*Duration of action = 1-2hr
 
== Magnesium ==
 
=== Adult Dosing ===
 
*Loading dose = 1-2gm in 10mL D5W over 1-2min (cardiac arrest)
*Loading dose = 1-4gm in 50-100 D5W over 20-60min (spontaneous circulation)
 
=== Contraindications ===
 
=== Indications ===
 
*Torsades
*Refractory v-tach/fib (regardless of Mg level)
 
=== Mechanism of Action ===
 
*Increases vasomotor tone
*Prolongs AV conduction; prolongs refractoriness
 
=== Adverse Drug Rxns ===
 
*Hypotension (rare)
 
=== Kinetics ===
 
*Onset of action = Immediate
*Duration of action = 30min
 
=== Source ===
 
Tintinalli
 
<br/>[[Category:Drugs]] <br/>[[Category:Cards]] <br/><br/><br/>

Latest revision as of 18:13, 14 August 2017

Table

Class Known as Examples Mechanism Clinical uses
Ia fast-channel blockers-Affect QRS complex (Na+) channel block (intermediate association/dissociation)
  • Ventricular arrhythmias
  • prevention of paroxysmal Recurrent atrial fibrillation (triggered by Vagus nerve overactivity)
  • procainamide in Wolf Parkinson White (WPW)
Ib- Do not affect QRS complex (Na+) channel block (fast association/dissociation)
  • treatment and prevention during and immediately after Myocardial infarction, though this practice is now discouraged given the increased risk of Asystole
  • Ventricular tachycardia
  • Atrial fibrillation
Ic (Na+) channel block (slow association/dissociation)
  • prevents Paroxysmal atrial fibrillation
  • treats Recurrent tachyarrhythmias of abnormal conduction system.
  • contraindicated immediately post-myocardial infarction.
II Beta-blockers beta blocking
Propranolol also shows some class I action
  • decrease Myocardial infarction mortality
  • prevent recurrence of Tachyarrhythmias
III

K+ channel blocker

Sotalol is also a β-blocker

Amiodarone has Class I, II, and III activity

IV slow-channel blockers Ca2+ channel blocker
  • prevent recurrence of Paroxysmal supraventricular tachycardia
  • reduce Ventricular rate in patients with Atrial fibrillation
V Work by other or unknown mechanisms (Direct nodal inhibition).

Used in supraventricular arrhythmias,

Or in the case of magnesium sulfate, used in torsade de pointes.

See Also

References


  • Katzung & Trevor's Pharmacology
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