9 - Drugs & Allergy Flashcards
(48 cards)
What is an allergy?
- Inflammatory disorder
- Maladaptive immune system response creating memory antigens
What are the key cells involved in allergic reactions?
- Mast cells
- Basophils
- Eosinophils
- Dendritic cells
- T-cells (Th 1 and 2)
- B-cells
- Plasma cells
What are mast cells?
- Tissue cells of immune system found in loose connective tissue, organs, vasculature, nerves, skin, respiratory tract, etc
- Not present in epidermal cells, CNS, or gastric mucosa
- Store histamine, interleukins, proteoglycans (ex: heparin), and various enzymes in their granules at cytoplasm
- Granules released upon stimulation of allergen (degranulation)
What happens when mast cell granules are released?
- Increased blood flow and permeability of blood vessels
- Contraction of smooth muscles
- Increased mucous production and fluid secretion
What is the effect of degranulation on the GI tract?
Expulsion of contents (diarrhea, vomiting)
What is the effect of degranulation on airways?
- Congestion and blockage of airways (wheezing, coughing, phlegm)
- Swelling and mucous secretion in nasal passages
What is the effect of degranulation on blood vessels?
- Increased fluid in tissues causing increased flow of lymph to lymph nodes
- Increased cells and protein in tissues
- Increased effector response in tissues
What allergy symptoms are caused by histamine and prostaglandins?
- Tickling
- Itchiness
- Nose rubbing (allergic salute)
What allergy symptoms are caused by histamine and leukotrienes?
- Sneezing
- Runny nose
- Post nasal drip
- Throat clearing
What allergy symptoms are caused by histamine, leukotrienes, bradykinin, and platelet activating factor?
- Nasal congestion
- Stuffy nose
- Congested airway => snoring
Where is histamine stored?
Tissue mast cells and blood basophils
What can cause cells to release histamine?
- Antigens (immediate hypersensitivity)
- Drugs (morphine, succinylcholine)
- Insect venoms
- Physical factors (scratching, cold)
Which histamine receptor is most important in allergic disorders?
H1
What does activation of the H1 receptor cause?
- Gastric and respiratory smooth muscle contraction
- Vasodilation
- Increased vascular permeability
- Itching
- Increased bronchial secretions and viscosity
What does activation of the H2 receptor cause?
Gastric acid secretion
What is the main function of H3 receptors?
Neurotransmitter control
What is the main function of H4 receptors?
Immune response regulation
What does activation of H1 and H2 receptors cause?
- Reduced BP
- Skin vasodilation
What is the response when the skin is pricked w/ an allergen?
- Red area at site of injection (vasodilation)
- Wheal replaces red area (edema)
- Bright red flare, indirect vasodilation (axonal reflex)
What is the pharmacotherapy for allergic rhinitis?
- Antihistamines
- Intranasal glucocorticoids
- Leukotriene modifiers
- Decongestants
- Mast cell stabilizers
- Anticholinergics
- Anti-IgE therapy
What will H1 receptor blockage cause?
- Decreased itching
- Decreased vascular permeability
- Decreased bronchial secretions
- Relaxation of bronchial smooth muscle
- Decreased cough receptor stimulation
What are some additional effects of antihistamines?
- 1st gen have non-histamine blockage actions, like sedation, atropinic, and anti-emetic
- 2nd and 3rd gen prevent mast cell release of mediators that cause inflammation
How can antihistamines be administered?
- Oral
- Intranasal
- IV (only used later in anaphylaxis but benefit questionable)
How are antihistamines metabolized?
CYP P450 system
