Pulmonology Book


Benzonatate Overdose

Aka: Benzonatate Overdose, Benzonatate Poisoning, Benzonatate Toxicity, Tessalon Overdose
  1. See Also
    1. Benzonatate (Tessalon)
  2. Background
    1. Tessalon Perles appear candy-like and could be ingested by young children
    2. Capsules are toxic if broken open (e.g. chewed, sucked) or taken in Overdose
      1. Single capsule may be lethal to child if the capsule leaks its liquid contents into the mouth
      2. McLawhorn (2013) Pharmacotherapy 33:38-43 +PMID:23307543 [PubMed]
    3. Narrow therapeutic range
      1. A small handful of capsules in Overdose could be lethal in adults
    4. Lethal effects of Benzonatate have likely been underestimated in past
      1. Benzonatate is rapidly metabolized and only recently have its metabolites been tested in autopsy cases
  3. Mechanism: Toxicity
    1. Sodium Channel Blocker
    2. Anesthetizes respiratory tract vagal stretch receptors
  4. Pharmacokinetics
    1. Adults
      1. Toxicity at >600 mg
    2. Young children
      1. Toxicity at >100 mg (esp. capsule chewed or crushed)
  5. Signs: Toxicity
    1. Rapid onset of symptoms (within 30 minutes of ingestion)
    2. Respiratory
      1. Laryngospasm or Bronchospasm
      2. Aspiration
      3. Respiratory Arrest
    3. Cardiovascular
      1. Hypotension or cardiovascular collapse
      2. Tachycardia
      3. Ventricular Tachycardia
      4. Torsades de Pointes
      5. Ventricular Fibrillation
      6. Cardiac Arrest
    4. Gastrointestinal
      1. Nausea or Vomiting
    5. Neurologic
      1. Dizziness
      2. Headache
      3. Agitation
      4. Muscle Twitching or Tremors
      5. Generalized Tonic Clonic Seizures
      6. Coma
  6. Labs
    1. Benzonatate Levels are not typically available and unlikely to be useful (rapidly metabolized)
    2. See Unknown Ingestion
      1. Includes evaluation and management including general toxicology labs
  7. Management
    1. Gastric Decontamination
      1. Not recommended unless polysubstance ingestion
      2. Benzonatate is rapidly absorbed
    2. Seizures
      1. Benzodiazepines
    3. Cardiovascular instability (Hypotension, dysrythmia)
      1. Hypotension with Wide QRS
        1. Sodium Bicarbonate 1-2 mEq/kg boluses until QRS narrows
      2. Other measures
        1. Intralipid (20% Lipid Emulsion) 1.5 ml/kg
        2. ECMO
    4. Disposition
      1. Admit all symptomatic patients
      2. Observe for 4-6 hours after intentional ingestion or pediatric ingestion >1 capsule
  8. References
    1. Tomaszewski (2021) Crit Dec Emerg Med 35(7):32
    2. Bishop-Freeman (2017) J Anal Toxicol 41:461-3 [PubMed]

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