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wikitox:2.1.11.4.2_antihistamines [2025/06/02 22:45] – kharriswikitox:2.1.11.4.2_antihistamines [2025/06/03 00:08] (current) – kharris
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-===== SUMMARY =====+===== OVERVIEW =====
  
-This monograph discusses the assessment and management of sedating antihistamines. For management of less-sedating antihistamines, see [[:wikitox:non_sedating_antihistamines|Non-Sedating Anithistamines]]+This monograph discusses the assessment and management of sedating antihistamines. For management of less-sedating antihistamines, see [[:wikitox:non_sedating_antihistamines|Non-Sedating Antihistamines]]
  
 There are many agents in this class including brompheniramine, chlorphenamine, cyclizine, cyproheptadine, dexchlorpheniramine, dimenhydrinate, diphenhydramine, doxylamine, pheniramine and promethazine. Many are available as individual agents, but several can also be found in co-formulation with other medications such as ibuprofen and paracetamol in cold and flu medicines or motion sickness remedies. There are many agents in this class including brompheniramine, chlorphenamine, cyclizine, cyproheptadine, dexchlorpheniramine, dimenhydrinate, diphenhydramine, doxylamine, pheniramine and promethazine. Many are available as individual agents, but several can also be found in co-formulation with other medications such as ibuprofen and paracetamol in cold and flu medicines or motion sickness remedies.
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 ===== RISK ASSESSMENT ===== ===== RISK ASSESSMENT =====
  
-With the exception of diphenhydramine, dimenhydrinate and promethazine, the toxic dose of agents is not well defined, except to say that toxicity is dose dependant.+With the exception of diphenhydramine, dimenhydrinate and promethazine, the toxic dose of agents is not well defined, except to say that toxicity is dose dependent.
  
 **Diphenhydramine**: Ingestions of >1g are associated with severe effects. Ingestion of <300mg or (<7.5mg/kg in children) are unlikely to have significant effects. **Diphenhydramine**: Ingestions of >1g are associated with severe effects. Ingestion of <300mg or (<7.5mg/kg in children) are unlikely to have significant effects.
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 Sedating antihistamines are generally well absorbed from the gastrointestinal tract, with peak plasma concentrations typically reached within 2 to 3 hours after oral administration. Sedating antihistamines are generally well absorbed from the gastrointestinal tract, with peak plasma concentrations typically reached within 2 to 3 hours after oral administration.
  
-==== Distrubution ====+==== Distribution ====
  
 These drugs are lipophilic and widely distributed throughout the body, readily crossing the blood–brain barrier, which contributes to their central sedative effects. These drugs are lipophilic and widely distributed throughout the body, readily crossing the blood–brain barrier, which contributes to their central sedative effects.
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 ===== CLINICAL EFFECTS ===== ===== CLINICAL EFFECTS =====
  
-In general ingestions of all agents in this group lead to dose-dependant sedation and anticholinergic toxicity. The initial sedation often masks an underlying anticholinergic delirium which then becomes more troublesome as the sedation lifts (typically after 6-18hrs).+In general, ingestions of all agents in this group lead to dose-dependent sedation and anticholinergic toxicity. The initial sedation often masks an underlying anticholinergic delirium which then becomes more troublesome as the sedation lifts (typically after 6-18hrs).
  
   * **CNS**: sedation (dose-dependent), anticholinergic toxicity, seizures (most commonly seen with pheniramine).   * **CNS**: sedation (dose-dependent), anticholinergic toxicity, seizures (most commonly seen with pheniramine).