Antihistamine

• A common OTC & prescription medication that is used for:

  ● Motion sickness control

  ● Allergy-related itching

  ● Cough & Cold palliation

  ● Sleep aids
• • Acute intoxication results to symptoms very similar to anticholinergic poisoning
• Cimetidine, Ranitidine, and Famotidine

  • H2 receptor blockers
  • Inhibits the gastric acid secretion
  • Do not produce significant intoxication
• MECHANISM OF TOXICITY

  H1 blocker antihistamines

  Structurally related to the histamines

  • Antagonize the effects of histamine on the H1 receptor sites
• Mechanism of Toxicity

  Possess anticholinergic effects

  • Stimulate or depress the CNS and some agents (e.g. Diphenhydramine, Promethazine) having local anesthetics and membrane-depressant effects in large doses
• PRINCIPAL SYMPTOMS: Coma & Convulsion
• OVERDOSE SYMPTOMS:

  ● Drowsiness

  ● Dilated pupils

  ● Flushed dry skin

  ● Fever

  ● Hallucinations

  ● Delirium
• TREATMENT

  1.Maintain the airway & assist ventilation if necessary

  2. Treat coma, seizures, and hyperthermia if they occur

  3. There is no specific antidote

  4. Perform gastric lavage

  Note: Inducing emesis is prohibited because of the risk of abrupt onset of seizures & coma