IC5 Management of Immune-mediated Toxicity Flashcards
What is the difference between drug allergies and hypersensitivity reactions?
Drug Allergies = Immunologically mediated response in a sensitized person
Hypersensitivity = Not proven to be immunologically mediated but can involve mediators released from mast cells and basophils caused by drugs
3 Examples of Drug Hypersensitivity Reactions
Vancomycin - Red Man Syndrome (Histamine)
ACEi/ARB - Angioedema (Bradykinin)
NSAIDs - Asthma (Prostaglandin)
What effectors of Allergic/Hypersensitivity reactions can be involved?
Innate and Adaptive - IgE, Cytokines, Complements, Cellular elements
Mediators released - Histamine, PAF, PG, Thromboxanes, Leukotrienes
4 Classifications of Allergic Reactions
- Immediate Hypersensitivity (Mast cells, IgE, eosinophils)
- Antibody-mediated Diseases (IgM, IgG)
- Immune Complex-mediated Diseases (IgM and IgG complexes deposit in vascular basement membrane)
- T Cell-mediated Diseases (CD4 and CD8)
3 Most reported drugs causing anaphylaxis
- Penicillin
- NSAID
- Insulin
What is anaphylaxis?
Acute, life-threatening reaction
Involves multiple organ systems
When is the risk of fatal anaphylaxis the greatest?
Within the first few hours
Signs of Anaphylaxis - Where do they normally present?
Skin - Urticaria (Hives), Itch/flush skin, swelling lips/tongue/throat/face
Airway - Tight/Swelling throat, hoarseness, scratchy throat, SOB, wheeze, chest tight
CVS - Chest pain, Low BP, Rapid HR
GIT - N/V/D, abdominal cramp
CNS - Tunnel vision, confusion, dizziness
Other clinical manifestations of allergy/hypersensitivity
- Serum sickness (Drug Fever) - Abx
- Drug induced autoimmunity (SLE)
- Vasculitis - Allopurinol, thiazide
- Asthma/Acute infiltrative & chronic fibrotic pulmonary reactions - Bleomycin, Nitrofurantoin
- Hematologic (Eosinophilia - Drug Hypersensitivity; Hemolytic anemia, thrombocytopenia, agranulocytosis)
What is SCAR? Three types of SCAR?
Serious Cutaneous Adverse Reactions
1. Drug Rash with Eosinophilia and Systemic Symptoms (Dress)
2. Mucocutaneous Disorders (SJS and TEN)
The DRESS Triad
Rash, Eosinophilia, Internal Organ involvement (Hepatitis, Interstitial Nephritis, Carditis, Adenopathy, Pneumonia)
Big culprits of DRESS
Allopurinol
Anticonvulsants
Presentation of SJS and TEN
Progressive bullous or “blistering” disorders (Dermatologic emergencies)
Progression - Mucus membrane erosion, Epidermal Detachment
Which is more severe? SJS or TEN?
TEN is more severe than SJS
1) >30% vs <10% detachment of body surface area
2) Mortality rate of TEN is higher (10-70% vs 1-5%)
What drugs cause SJS and TEN?
Antibiotics (Sulfonamides especially)
4 Common drugs that have been more genetically disposed to drug allergy or hypersensitivity
- Abacavir
- Allopurinol
- Phenytoin
- Carbamazepine
Which drug requires compulsory pharmacogenomic testing?
Carbamazepine
5 Therapeutic Actions for Anaphylaxis Treatment
- Epinephrine - HR and BP
- IV fluid - BP / Blood volume
- Intubation - Airway
- Norepinephrine - If shock
- Others: Steroids, glucagon, diphenhydramine (H1) + Ranitidine (H2)
How is SCAR treated?
Supportive care (Similar to burn patients)
- Wound care
- Nutritional support
- Fluids
- Temperature regulation
- Pain management
- Prevention of infections
What is controversial in the use of SCAR treatment?
Steroids