Type I Hypersensitivity Flashcards
What kind of hypersensitivity is Type I Hypersensitivity?
Immediate
What is Type I HS mediated by?
IgE antibody release
How is Type I HS clinically presented?
Respiratory depression, laryngeal edema, hypotension, CV collapse
Severe anaphylaxis
Rapid after exposure to allergen (30 minutes-2 hours), fatality is greatest in the first few hours
Drug-induced Type I hypersensitivity is most commonly seen in what drug?
Penicillin
PCN and beta-lactam cross-reactivity is due to what?
The side chain moieties
What can be administered to patients with a PCN allergy?
Aztreonam
What should be avoided in patients with a positive PCN test?
Carbapenems
Primary mediators of a type I reaction
Histamine, chemotactic factors, proteases
Secondary mediators of a type I reaction
leukotrienes, prostaglandin D2
Treatment for Type I reaction
Epinephrine Oxygen therapy Diphenhydramine Ranitidine (late phase) IV fluids if hypotensive IV hydrocortisone sodium succinate
Patho of type I hypersensitivity
Allergen recognized by macrophage -> T-helper cell assists and macrophage presents the digested allergen to a B cell -> B cell becomes sensitized and becomes committed to that specific allergen -> plasma cells create IgE while some B cells become memory cells and lay dormant until the next exposure
In future exposures, cross-linking occurs on mast cells and will crosslink when they see the allergen and start degranulating
What can you do to determine if a patient has an allergy to PCN?
Use a Pre-Pen to determine if a reaction will occur
Desensitization
The process of administering gradual increased doses of a drug over time in an attempt to develop clinical tolerance
What kind of patients do you use desensitization in?
Patients with a documented drug allergy that requires treatment with that specific drug and there’s NO alternate available
