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cardio:arrhythmias:atropine [2026/02/13 17:14] – created andrew2393cnscardio:arrhythmias:atropine [2026/02/13 17:16] (current) – andrew2393cns
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 <WRAP right 300px> <WRAP right 300px>
 <WRAP infobox> <WRAP infobox>
-^ Drug Overview | +^ Drug Overview | {{ :cardio:arrhythmias:atropine.svg |}}| 
-| Class | [[cardio:autonomics:antimuscarinics|Antimuscarinics]] |+| Drug Class | [[cardio:autonomics:antimuscarinics:start|Antimuscarinics]] |
 | Subclass | Competitive Muscarinic Antagonist | | Subclass | Competitive Muscarinic Antagonist |
-| Primary CV Use | Symptomatic Bradycardia | +| Primary CV Use | [[cardio:arrhythmias:bradycardia|Symptomatic Bradycardia]] | 
-| Route | IV / IM / SQ / Ophthalmic |+| Route | IV / IM / SQ / [[ophthalmology:mydriatics:start|Ophthalmic]] |
 | Onset (IV) | 1–2 minutes | | Onset (IV) | 1–2 minutes |
 | Duration | 30–60 minutes | | Duration | 30–60 minutes |
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 | Black Box Warning | No | | Black Box Warning | No |
 | Controlled | No | | Controlled | No |
-| FDA Approval | 1939 | 
 </WRAP> </WRAP>
 </WRAP> </WRAP>
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 Atropine is a competitive antagonist of muscarinic acetylcholine receptors. Atropine is a competitive antagonist of muscarinic acetylcholine receptors.
  
-In cardiovascular practice, it is used to treat symptomatic bradycardia by blocking parasympathetic (vagal) tone at the SA and AV nodes.+In cardiovascular practice, it is used to treat [[cardio:arrhythmias:bradycardia|symptomatic bradycardia]] by blocking parasympathetic (vagal) tone at the SA and AV nodes.
  
 It increases heart rate by removing inhibitory cholinergic signaling. It increases heart rate by removing inhibitory cholinergic signaling.
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 Primary Target: Primary Target:
-  * M2 muscarinic receptors in the SA and AV nodes+  * M2 muscarinic receptors in the SA and AV nodes (see [[cardio:autonomics:muscarinic_receptors|Muscarinic Receptors]])
  
 Normal Physiology: Normal Physiology:
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 Net Effect: Net Effect:
-  * Increased heart rate+  * ↑ Heart rate
   * Improved AV conduction   * Improved AV conduction
  
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 Cardiovascular: Cardiovascular:
-  * Symptomatic sinus bradycardia +  * [[cardio:arrhythmias:bradycardia|Symptomatic sinus bradycardia]] 
-  * AV nodal block (vagal-mediated)+  * [[cardio:arrhythmias:av_block|Vagal-mediated AV nodal block]]
  
-Advanced Cardiac Life Support (ACLS): +ACLS: 
-  * First-line for unstable bradycardia+  * First-line medication for unstable [[cardio:arrhythmias:bradycardia|bradycardia (ACLS)]]
  
 Other Uses: Other Uses:
-  * Organophosphate poisoning +  * [[toxicology:organophosphates:start|Organophosphate poisoning]] 
-  * Pre-anesthetic to reduce secretions +  * Pre-anesthetic reduction of secretions 
-  * Ophthalmic dilation+  * [[ophthalmology:mydriatics:start|Ophthalmic mydriasis/cycloplegia]]
  
 -------------------------------------------------------------------- --------------------------------------------------------------------
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   * Doses < 0.5 mg may paradoxically worsen bradycardia   * Doses < 0.5 mg may paradoxically worsen bradycardia
  
-Pediatric dosing differs — weight-based.+If ineffective: 
 +  * Proceed to [[cardio:arrhythmias:bradycardia|pacing / pressor support]] (see [[cardio:arrhythmias:bradycardia|Bradycardia Algorithm]])
  
 -------------------------------------------------------------------- --------------------------------------------------------------------
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 Absolute: Absolute:
-  * None in emergent bradycardia+  * None in emergent unstable bradycardia situations
  
-Relative: +Relative / Cautions: 
-  * Glaucoma +  * [[ophthalmology:glaucoma:start|Narrow-angle glaucoma]] 
-  * Severe tachyarrhythmias+  * Severe tachyarrhythmias (see [[cardio:arrhythmias:start|Dysrhythmias]])
   * Obstructive uropathy   * Obstructive uropathy
   * Ileus   * Ileus
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 ===== Adverse Effects ===== ===== Adverse Effects =====
  
-Common (Anticholinergic effects): +Common (anticholinergic effects):
   * Tachycardia   * Tachycardia
   * Dry mouth   * Dry mouth
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   * Arrhythmias   * Arrhythmias
   * Hyperthermia (impaired sweating)   * Hyperthermia (impaired sweating)
 +
 +Mechanism-based:
 +  * “Hot as a hare, dry as a bone, blind as a bat, mad as a hatter”
  
 -------------------------------------------------------------------- --------------------------------------------------------------------
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 Additive anticholinergic effects with: Additive anticholinergic effects with:
 +  * [[cardio:autonomics:antimuscarinics:start|Other antimuscarinics]]
 +  * [[psych:tcAs:start|Tricyclic antidepressants (TCAs)]]
 +  * [[psych:antipsychotics:start|Antipsychotics]]
 +  * [[allergy:antihistamines:start|First-generation antihistamines]]
  
-  * [[cardio:autonomics:antimuscarinics|Other Antimuscarinics]] +Bradycardia context / AV node: 
-  * Antihistamines +  * Use caution if combined with AV nodal blockers: 
-  * TCAs +    * [[cardio:beta_blockers:start|Beta-Blockers]] 
-  * Antipsychotics +    * [[cardio:ccb:non_dhp|Non-DHP Calcium Channel Blockers]] 
- +    * [[cardio:arrhythmias:digoxin|Digoxin]]
-Use caution with: +
-  * AV nodal blocking agents+
  
 -------------------------------------------------------------------- --------------------------------------------------------------------
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   * Blood pressure   * Blood pressure
   * Mental status (elderly)   * Mental status (elderly)
 +  * Signs of anticholinergic toxicity
  
 -------------------------------------------------------------------- --------------------------------------------------------------------
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 ===== Clinical Pearls ===== ===== Clinical Pearls =====
  
-  * Removes vagal tone — does NOT stimulate the heart directly +  * Atropine removes vagal tone — it does NOT increase contractility directly. 
-  * Ineffective in Mobitz II or complete heart block distal to AV node +  * Ineffective in infranodal block (e.g., [[cardio:arrhythmias:av_block|Mobitz II / complete heart block distal to AV node]]). 
-  * Avoid low doses (< 0.5 mg IV) +  * Avoid low doses (< 0.5 mg IV) due to paradoxical bradycardia. 
-  * First-line ACLS drug for unstable bradycardia +  * If no response, escalate quickly to [[cardio:arrhythmias:bradycardia|pacing and/or pressors]].
-  * Consider pacing if ineffective+
  
 -------------------------------------------------------------------- --------------------------------------------------------------------
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 ===== Comparison Within Arrhythmia Management ===== ===== Comparison Within Arrhythmia Management =====
  
-Compared to: +Opposite AV nodal effects compared to: 
-  * [[cardio:arrhythmias:adenosine|Adenosine]] — slows AV node +  * [[cardio:arrhythmias:adenosine|Adenosine]] (transient AV nodal block) 
-  * [[cardio:beta_blockers:start|Beta-Blockers]] — reduce sympathetic tone+  * [[cardio:beta_blockers:start|Beta-Blockers]] (↓ sympathetic tone) 
 +  * [[cardio:ccb:non_dhp|Non-DHP CCBs]] (↓ AV nodal conduction)
  
 Atropine: Atropine:
-  * Blocks parasympathetic tone +  * ↑ SA node rate 
-  * Increases heart rate +  * ↑ AV conduction 
-  * Short-acting +  * Used for bradycardia, not tachyarrhythmias
-  * Used in bradycardia (not tachyarrhythmia)+
  
 -------------------------------------------------------------------- --------------------------------------------------------------------
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   * [[cardio:arrhythmias:start|Dysrhythmias Module]]   * [[cardio:arrhythmias:start|Dysrhythmias Module]]
 +  * [[cardio:arrhythmias:bradycardia|Bradycardia]]
   * [[cardio:arrhythmias:adenosine|Adenosine]]   * [[cardio:arrhythmias:adenosine|Adenosine]]
   * [[cardio:beta_blockers:start|Beta-Blockers]]   * [[cardio:beta_blockers:start|Beta-Blockers]]
 +  * [[cardio:ccb:start|Calcium Channel Blockers]]
   * [[cardio:intro:start|Cardiovascular Pharmacology]]   * [[cardio:intro:start|Cardiovascular Pharmacology]]
cardio/arrhythmias/atropine.1771002861.txt.gz · Last modified: by andrew2393cns