From: World Allergy Organization Guidelines for the Assessment and Management of Anaphylaxis
Medication | H1-Antihistaminesa (eg. Intravenous Chlorpheniramine or Diphenhydramine; Oral Cetirizine) | Beta-2 Adrenergic Agonistsa (eg. Salbutamol [Albuterol] by Inhalation) | Glucocorticoidsa (eg. Intravenous Hydrocortisone or Methylprednisolone; Oral Prednisone or Prednisolone) |
---|---|---|---|
Strength of recommendation for use in anaphylaxisb | C | C | C |
Pharmacologic effects | At H1-receptor, inverse agonist effect; stabilize receptors in inactive conformation; decrease skin and mucosal symptoms | At beta-2 receptor, increase bronchodilation | Switch off transcription of activated genes that encode pro-inflammatory proteins; decrease late phase allergic response |
Clinical relevance | Decrease itch, flush, urticaria, sneezing, and rhinorrhea, but are not life-saving because they do not prevent or relieve obstruction to airflow or hypotension/shock | Decrease wheeze, cough and shortness of breath but are not life-saving because they do not prevent or relieve upper airway obstruction or hypotension/shock | Onset of action takes several hours; therefore, are not life-saving in initial hours of an anaphylactic episode; used to prevent and relieve protracted or biphasic anaphylaxis; however, these effects have not been proven |
Potential adverse effects (usual dose) | First-generation drugs cause drowsiness, somnolence, and impaired cognitive functionc | Tremor, tachycardia, dizziness, jitteriness | Unlikely during a short course |
Potential adverse effects (overdose) | Extreme drowsiness, confusion, coma, respiratory depression, and paradoxical central nervous system stimulation, eg. seizures in infants and children | Headache, hypokalemia, vasodilation | Unlikely |
Comment | From 0 to 14 different H1-antihistaminesc and different dose regimens are listed as adjunctive medications in anaphylaxis guidelines; role not proven | Use in anaphylaxis is extrapolated from use in acute asthma; if given as adjunctive treatment for bronchospasm not relieved by epinephrine, should optimally be delivered by face mask and nebulization | From 0 to 3 different glucocorticoidsd and different dose regimensd are listed as adjunctive medications in anaphylaxis guidelines; role not proven |