L80 - Anti-Allergic Drugs Flashcards
Location of Mast Cells?
Everywhere
Particularly prevalent as body sites in contact with the external environment, Skin/Gut/Resp
Commonly found close to blood vessels/nerves/glands
What is required for allergen-induced mast cell degranulation?
- Cros slinkng of IgE bound Fc epsilon R1
2. Requires antigen specific IgE produced in atopic subjects (heritable trait)
Which is Allergenic? Dust Mites Pollen Cats Peanuts
Dust Mites
Now explain why…
How do mast cells immediately commnicate with the internal environment?
Histmaine
Heparin
Tryptase
TNF-alpha
Preformed Mediators
30-45 seconds
How does the mast cell rapidly communicate with the internal environemnt?
Cys-LTs
PGD2
peaks over 10-30minutes
How does the mast cell slowly communicate with it’s internal environment
IL-4
IL-5
GM-CSF
Late, T-cell and eosinophil dependent reaction
What is released immediately from mast cells and what does it act on and what are it’s results?
Histamines - Act on H1 receptors (and H2 actions in brackets)
Pain and itch (sensory nerve action) Bronchospasm Mucus secretion vasodilation/hypotension Increased ascular leak - hypovalemia (Positive inotropic and chronotropic) (Gastric acid secretion) CNS - increased wakefulness
Where are the LTC4 and metabolites (LTD4 and LTE4) active?
CysLT1 receptor
Endogenous Inhibitors of mast cell activation?
PGE2, adrenaline, cortisol
What are glucocorticoids used for?
Inhibiting Mediator Production
What conditions may require Glucocorticoids?
Asthma, hypersensitivity/systemic anaphylaxis
What can H1 receptor antagonists be used for?
Inhibiting Mediator actions
What are indications for use of H1 receptor antagonists
itching dermatitis hayfever anaphylaxis bites and stings motion sickness (muscarinic antagonist activity)
What are the 3 classes of H1 receptor antagonists?
Sedative
Non-Sedative
Newer Non-sedative
When are sedative H1 Receptors used?
May be neutral/beneficial in treatment of allergies, but sufficient to interfere with lifestyle