drug therapy to decrease histamine effects and allergic response

Question 1

describe histamine (H1)

Answer 1

-1st cemical mediator released in immune and inflammatory response
-found in mast cells and basophils
-released in response to stimuli (allergic reactions, cellular injury)
-after its release, its target cells are in the blood vessels, respiratory, and GI tract

Question 2

describe the allergic response

when histamine stimulates its receptors, what happens?

Answer 2

-contraction of smooth muscles in resp tract (can experience resp distress/wheezing)
-stimulation of vagus nerve (coughing, bronchoconstriction)
-increased permeability of veins and capillaries (edema)
-increased secretion from mucus glands
-stimulation of peripheral nerve endings (pain and itching)
-increase secretion of gastric acid
-increased HR and force

Question 3

describe hypersensitivity reactions

Answer 3

-involves an exaggerated allergic response
-can cause tissue damage or serious illness (anaphylactic reactions)
-caused by an abnormal immune reaction

-four types based on producing mechanism
-types I,II, III are antibody mechanisms
-type IV is antigen specific T cells

Question 4

describe type I hypersensitivity

Answer 4

immediate hypersensivitity
-occurs within minutes
-IgE induced mast cell activation
-usually after 2nd or later exposure
-mild to severe

mild: itching, rhinitis
severe: anaphylactic-respiratory distress, cardiac collapse, life threatening

Question 5

describe type II hypersensivitity

Answer 5

cytotoxic
-mediated by IgG or IgM
-generates direct damage to cell surface
-blood transfusion reactions
-hemolytic disease of newborns, hemolytic anemia

Question 6

describe type III hypersensivitity

Answer 6

immune complex
-mediated by IgG or IgM
-forms antigen-antibod complexes and acute inflammatory reaction in tissue
-serum sickness (excess antigens and antibodies building up -> can cause permanent tissue damage)

pretty rare -> usually seen after antibody transfusion or as a reaction to some medications

Question 7

describe type IV hypersensivitity

Answer 7

delayed hypersensivitity
-cell mediated response (not immediate)
-sensitized T lymphocytes react with antigen to cause inflammation
-tuberculin test, contact dermatitis, graft rejection

Question 8

true or false?

histamine is the first chemical mediator released during inflammatory response

Answer 8

true

histamine is the first chemical mediator released during immune and inflammatory response. it is synthesized and stored in most body tissues. especially ones exposed to the outside such as eyes, nose, mouth, and GI track

Question 9

true or false

four classifications of hypersensitivity reactions exist

Answer 9

true

four classifications of hypersensivitity reactions exist: type I (immediate), type II (direct damage to cell surfaces), type III (formation of antigen-antibody complexes), and type IV (delayed hypersensivitity)

Question 10

what is allergic rhinitis

Answer 10

inflammation of nasal mucosa caused by type I reaction to inhaled allergens

Question 11

what are some symptoms of allergic rhinitis

Answer 11

-nasal congestion
-itching, sneezing
-watery drainage
-itching of throat, eyes, and ears common

Question 12

what are two types of allergic rhinitis

Answer 12

-seasonal disease (AKA hay fever)
-perinnial disease

Question 13

describe seasonal disease (AKA hay fever)

Answer 13

response to airborne pollens

Question 14

describe perinneal disease

Answer 14

-response to nonseasonal allergens
-dust mites, molds
-animal dander

Question 15

describe allergic food reactions

Answer 15

-immune response to ingestion of a protein
-shellfish, fish, corn, seeds, bananas, egg, milk, soy, peanut, tree nuts
-higher risk of triggering anaphylaxis

-children allergic to milk, eggs, wheat, soy may outgrow their allergy, no known preventative

Question 16

describe contact dermatitis

Answer 16

-type IV reaction from direct contact with antigen
-poison ivy, cosmetics, metals

-affected skin is inflamed, warm , swollen, itchy
-blisters may form, drain, and become infected

-usually occurs 24hrs after contact

Question 17

describe drug reactions

Answer 17

-any drug can cause a reaction
-any body tissue may be involved
-symptoms vary but may include.. skin rash, itching, fever, hematologic or hepatic reactions
-may occur 7-10 days after initial exposure
-resolves after drug is discontinued

Question 18

true or false?

allergic rhinitis is caused by type III sensitivity

Answer 18

false

allergic rhinitis is inflammation of nasal mucosa caused by a type I hypersensitivity reaction to inhaled allergens

Question 19

what do antihistamines do?

Answer 19

relieve symptoms but do not relieve hypersensitivity

Question 20

what are antihistamines used for?

Answer 20

-allergic rhinitis
-anaphylaxis
-allergic conjunctivitis
-drug allergies, pseudoallergies
-blood/blood product transfusion
-dermatologic conditions, etc

Question 21

give an example of first generation H1 receptor anatgonists

Answer 21

diphenhydramine

Question 22

what do first generation H1 receptor anatgonists do?

Answer 22

-prevent/reduce most physiologic effects that histamine produces at receptor sites
-inhibit smooth muscle constriction in blood vessels, rep, GI tract
-decreases capillary permeability
-decrease salivation and tear formation

Question 23

describe the action of first generation H1 receptor anatgonists

Answer 23

occupy same receptors as histamine which prevents histamine from reaching target

Question 24

describe the use of first generation H1 receptor anatgonists

Answer 24

-allergic reactions
-motion sickness
-insomnia
-children may experience paradoxical effect

Question 25

what are some adverse effects of first generation H1 receptor anatgonists

Answer 25

-CNS depression
-anticholinergic effects

Question 26

what are some contraindications of first generation H1 receptor anatgonists

Answer 26

-narrow angle glaucoma
-BPH

Question 27

what are some nursing considerations with first generation H1 receptor anatgonists

Answer 27

-use caution in older adulta, may cause confusion
-may thicken secretions

Question 28

describe patient education with first generation H1 receptor anatgonists

Answer 28

-take med before exposure to allergen
-tolerance to drowsiness in few days
-avoid taking with alcohol
-avoid accidental OD

Question 29

give examples of second generation H1 receptor antagonists

Answer 29

-fexofenadine
-loratadine
-cetirizine

Question 30

what do second generation H1 receptor antagonists do?

Answer 30

-does not readily enter the brain from the blood
-bind preferentially to peripheral rather than central H1 receptors
-replacing first generation H1
-have mild beneficial effect in chronic asthma

Question 31

describe the action of second generation H1 receptor antagonists

Answer 31

occupy the same receptors as histamine which prevents histamine from reaching target

Question 32

describe the use of second generation H1 receptor antagonists

Answer 32

-seasonal allergic rhinitis
-minor allergies
-itching

Question 33

what are some nursing cosiderations with second generation H1 receptor antagonists

Answer 33

-safer in older adults
-use caution with renal failure

Question 34

describe patient education with second generation H1 receptor antagonists

Answer 34

-take med before exposure to allergen
-teach proper use of nasal spray if needed
-avoid taking with alcohol
-avoid accidental OD

Question 35

when explaining the options for antihistamines, the nurse explains that second generation H1 receptor antagonists differ from first generation H1 receptor antagonists by…

A) cause greater CNS sedation
B) are available by prescription only
C) are more cost effective
D) do not cross blood brain barrier

Answer 35

D) do not cross blood brain barrier

second generation H1 receptor antagonists like fexofenadine do not enter the brain reducing the side effect of sedation