Drug Allergies Flashcards
(28 cards)
Pesudoallergic reaction
Adverse drug reaction with similar clinical presentation to allergic reactions, BUT without immune system.
What is most common type of allergic drug reaction?
Type I (usually requires previous exposure)
Symptoms of Type I Allergic Reaction
- Hives or Rash (most common)
- Pruritus (itchy)
- Flushing
- Angioedema
- Wheezing
- GI symptoms
- Hypertension
- Anaphylaxis
FEVER IS NOT SEEN IN THIS TYPE!
Anaphylaxis Definition
An acute, life-threatening allergic reaction involving multiple organ systems
Under-recognized and under-treated
Anaphylaxis Manifestations
- Skin (80-90%)
- Respiratory tract (70%)
- GI (40%)
- CV (35%)
Time Course of Anaphylaxis
Rapid Onset
- Biphasic anaphylaxis: Recurrence within 6-10 hours
- Protracted anaphylaxis: Rare, Symptoms persist for more than a day.
Types of Angioedema (swelling)
-
Mast cell-mediated:
- Type I allergic reaction
-
Bradykinin-mediated:
- Associated with ACE inhibitors
- Not allergic
- Delayed onset
When exposure to allergen is known what will you commonly see?
Reduced BP after exposure to KNOWN antigen!
Criteria for Allergic Reaction when exposure is not known
Sudden onset of illness plus at least one: Sudden respiratory symptoms, Sudden reduced BP
What drugs commonly cause Type I Allergic Reaction?
- Beta lactams (penicillin)
- Cephalosporins
- Antibiotic sulfonamides
- Quinolones
Type II Allergic Reaction Symptoms:
Cytotoxic Reaction
- Hemolytic Anemia (destroy RBCs)
- Thrombocytopenia (low platelets)
- Leukopenia (low WBCs)
- Neutropenia ( low neutrophils)
How does heparin cause thrombocytopenia?
Causes increased risk for clotting.
Type III Allergic Reaction
Immune-complex hypersensitivity
Antibodies bind to drug and precipitate in tissue (causes inflammation)
Timing: delayed
Type III allergic reaction Symptoms:
- Fever, rash, arthralgia (pain in joint)
- Vasculitis
- Glomerulonephritis
- Drug Fever (also can happen in type IV)
What is difference between drug fever and infectious fever?
Fever will stop upon discontinuation of drug
Drug fevers are high
Patients w drug fever may not realize it
Presence of eosinophilia (drug fever)
Type IV Allergic Reaction
Cell-mediated (T cells)
Delayed
Type IV Allergic Reaction Symptoms
- Contact Dermatitis
- Skin stuff
What drugs cause SJS and TENs (Type IV)
- Antibiotic sulfa
- Beta lactam
- Phenobarbital, Carbamazepine, Phenytoin, Lamotrigine
- Allopurinol
- NSAIDs
- Nevirapine
- Abacavir
Most common drug w allergic reactions
Beta Lactams!
Second most common drug w allergic reactions?
Sulfa!!
Aspirin Allergy:
Samter’s Triad of symptoms:
- Uritcaria or angioedema
- Asthma exacerbations
- Rhinitis
HLA Testing Drugs
- Abacavir
- Carbamezapine
- Allopurinol
- Phenytoin
How to treat urticaria or muculopapular rash?
- discontinue offending agent
- Treat symptoms (histamines)
- Epinephrine can be given if theres a history of anaphylaxis
Management of Anaphylaxis?
- IM epineph
- Maintain O2 >92%
- Lay patient down on back and keep legs raised
