August 26, 2015 - Allergy Flashcards Preview

COURSE 1 > August 26, 2015 - Allergy > Flashcards

Flashcards in August 26, 2015 - Allergy Deck (12):

Idiosyncratic Adverse Reaction

The cause of unknown. We don't know why it happened.


Class Effect

All related drugs exhibit the same "reaction".


Multiple Drugs and Toxicities

Don't double-stack the toxicities of drugs. This greatly increases the chance and severity of an adverse effect.


Type 1 Hypersensitivity

Anaphylactic reaction. Mediated primarily through IgE.

May be de-sensitized if the drug must be used by starting with a very small dose and working your way up. This causes gradual degranulation of mast cells and basophils rather than them all dumping at once.


Type 2 Hypersensitivity


Mediated by IgG or IgM. Results in the hemolysis of RBCs, WBCs, platelets, etc.

The antibody WITH the drug binds to a cell. Just the Ab by itself, or just the drug itself isnt a problem, but when they mix together it causes a cytotoxic effect.


Type 3 Hypersensitivity

Occurs when antigen-antibody complexes are not adequately cleared and they accumulate, giving rise to an inflammatory response. These may become deposited in tissues and cause inflammation.

Mediated by IgM or IgG.


Type 4 Hypersensitivity

Delayed type hypersensitivity. This is mediated by cells, rather than antibodies. Helper T cells recognize the antigen in a complex with the APC macrophages and invoke an immune response. Macrophages are activated and cause an inflammatory response which ultimately leads to tissue damage.


Treatment of Type 1 Hypersensitivity

ALWAYS stop the offending agent first

Phone a friend

If mild, use steroids, anti-histamines, and block histamine release.

If severe, use epinephrine and always go to the hospital because the effects of the epinephrine are often less long-lived than the offending agent.


Mononucleosis and Amoxicillin

If infected by EBV and are given amoxicillin, 40% of patients will develop a rash. They are not allergic to the amoxicillin.


Side-Chain and Allergies

Most allergies are associated with the side chain rather than the core structure. The side chain can be used to predict cross-reactivity with other drugs that contain a similar side chain.


Steven-Johnson Syndrome

Is a form of toxic epidermal necrolysis in which the epidermis seperates from the dermis. It is caused rarely by some medications.

If less than 10% of the skin, it is considered Steven-Johnson Syndrome. If more than 30% of the skin, it is known as Toxic Epidermal Necrolysis.

Patients must be treated like a severe burn patient. It affects the mucus membranes, so if a patient presents with a rash, ALWAYS check the inside of the mouth. Discontinue the drug if anything is in the mouth.


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