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50 Cards in this Set
- Front
- Back
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Histamine is found in particularly high concentration in these three places?
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Lung
Skin GI tract |
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Three stages of inflammation
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Immediate hypersensitivity
Delayed subacute phase Chronic proliferative phase |
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Immediate hypersensitivity
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vascular permability (H1&2)
smooth muscle contraction (H1) vasodilation (H1 &2) bronchospasm (H1) pain and itiching (kinin's) |
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Delayed subacute phase
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Infiltration of leukocytes and phagocytes
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Chronic proliferative phase
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Tissue degeneration and fibrosis or repair
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How is histamine synthesized?
How is it inactivated? |
histidine decarboxylase
methylation or oxidative deamination |
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Three methods of histamine release
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Cell damage
Ca dependent exocytosis Ca independent exocytosis (basic compounds like morphine and tubocurarine) |
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Inhibition of histamine release
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Cyclimc AMP-linked receptor agonists (beta 2, H2, PGE 2)
Theophylline Cromolyn sodium (lung mast cells) |
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H1 receptors
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smooth muscle
endothelium brain linked to phospholipase C -> IP3, DAG |
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H2 receptors
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gastric mucosa, mast cells, cardiac, brain
cAMP formation |
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H3 receptors
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Brain
Myenteric plexus Presynaptic |
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Receptor in endothelium
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H1
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Recetpor in myenteric plexus
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H3
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Receptor in gastric mucosa
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H2
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Receptor in brain
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H1, H2, H3
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Receptor in cardiac muscle
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H2
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Linked to phospholipase C
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H1
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Linked to cAMP
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H2
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Histamine effects this receptor to cause increased capillary permeability
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H1
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What is the difference between H1 and H2 vasodilation
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H1 is rapid and short
H2 is slow, but sustatined |
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This receptor increass gastric acid secretion
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H2
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Increass gastirc acid motility
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H1
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Bronchial effects
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H1
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Two uses for histamine
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Test gastirc acid secretion
Pheochromocytoma |
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Epinephrine as a histamine antagonist
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smooth muscle relaxer
a physiological antagonist |
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Cromylyn Sodium as a H antagonist
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inhibits mast cell degranulation
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First generation antihistamines
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Diphenhydramine
Chloropheniramine Pyrilamine Promethazine Meclizine |
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Second generation antihistamines
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Terfenadine
Astemizole Fexofendaine Loratadine |
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Are lipid soluble?
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1st generation
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Not sedative
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2nd generation
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Effective length of time for 2nd generation drugs
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12-24 hours
terfenadine astemizole fexofenadine loratadine |
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Penetrate the CNS
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1st generation
diphenhydramine chloropheniramine pyrilamine promethazine meclizine |
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Effective time for 1st generation
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4-6 hours
diphenhydramine chloropheniramine pyrilamine promethazine meclizine |
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Why do 1st generation drugs cause drowsiness
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A central H1 receptor is involved in the control of wakefullness
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CNS toxicity of H1 antagonist resembles?
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Atropine poisioning
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Two anti-H that cause serious cardia arrythmias
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terfenadine
astemizole |
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Method of arrythmia in terfenadine and astemizole
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Block delayed rectifier K channels
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When are terfeanadine and astemizole a risk for causing arrythmia's?
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In overdoes or with drugs that cause inhibition of cytochrome p450 (erthyromycin and antifungals)
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Receptor that mediates antihistamines anti-emetic effects
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M1 receptor
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Two Anti-H's with local anesthetic activity
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diphenyhydramine
promethazine |
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These have muscarinic cross reactivity
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diphenhydramine
meclizine promethazine (and other 1st gen) |
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terfenadine
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2nd generation antihistamine
Seldane may cause cardiac arrythmias |
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diphenydramine
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1st generation antihistamine
Bendadryl Local anestehtic activity Muscarinic cross reactivity |
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chloropheniramine
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1st generation antihistamine
Chlor-trimeton no antiemmetic effects |
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meclizine
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1st generation antihistamine
Antivert Muscarinic cross reactivity primarily for motion sickness |
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fexofenadine
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2nd generation antihistamine
Allegra 12 hours No interaction with cyto p450 inhibiting drugs |
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loratadine
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2nd generation antihistamine
Claritin 24 hours |
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pyrilamine
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1st generation antihistamine
OTC cold and sleep aid |
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Promethazine
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1st generation antihistamine
local anestehtic muscarinic cross reactivity alpha adrenocrecptor cross reactivity anti emmetic |
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astemizole
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2nd geneartion antihistamine
histamal risk of cardiac arrythmias |
