W4: Type B adverse drug reaction Flashcards
Type B ADR are idiosyncratic reactions. What does this mean?
Because type B ADR are unpredictable, has no relationship to dosage and the pharmacokinetics are unclear.
What is the hypothesized cause for immunological reactions (hypersensitivity, drug allergy)?
There is possibly a bio-activation of drugs, which leads to generation of reactive species and results in direct or immune-medicated toxicity.
Idiosyncratic reaction may occur due to _____ or acquired enzyme _______ with the formation of toxic metabolites.
Genetics or acquired enzyme abnormality
There is an immediate adverse reaction after exposure in type B ADR. True or False?
FALSE, there will be a delay between exposure and occurrence of the ADR.
Why type B ADR don’t have a formal dose-response curve?
because ADME cannot even explain how to plot a dose response graph worh.
Key features of type I (immediate hypersensitivity) are____?
- fast response
- release of histamine from mast cells and basophils due to IgE
- anaphylaxis reaction
Key features of type II (cytotoxic hypersensitivity) are _______?
- cellular destruction
- binding of IgG or IgM to cell surface antigen -> activate complement pathway
e.g. drug induced hemolytic anemia by penicillin
Key features of type III (immune -complex reaction) are _______?
- little amount of antibodies vs excess antigens
- formation of circulating antigen -antibody complex
- large complex clear by macrophage
- but small will fuse in blood vessels, joints or glomerulus.
- there small complexes can induce an inflammatory response
Key features of type IV (delayed hypersensitivity reaction) are _______?
- NO antibodies involved
- mediated by T helper cells when activated by APC (class II MHC).
- Activate macrophage and release interleukins for inflammatory response
- Delayed because takes few days to develop
