Autocoids (year 2) Flashcards
what are autocoids?
chemicals that act like local hormones
what are the classes of autocoids?
biogenic amines
lipid-derived
polypeptides
give some examples of biogenic amines
histamine and serotonin
what are the two classes of lipid derived autocoids?
eicosanoids
platelet activating factor
give some examples of eicosanoids
prostanoids
leukotrienes
give some examples of polypeptide autocoids
bradykinin, angiotensin, cytokines
what are histamines formed from?
histidine
where are histamines found in greatest concentration?
tissues exposed to the outside world such as skin, GI tract and lungs
where are histamines stored?
mast cells, basophils, histaminocytes (stomach)
what triggers histamines to be released?
response to food/vagal stimulation
response to inflammatory/allergic reactions
what type of receptors does histamine target?
G protein coupled receptors
what histamines receptors are drugs available for?
histamine 1 and 2
what are the normal functions of histamines?
gastric secretion (gastric acid production)
H1 stimulates smooth muscle contractions in GI and respiratory tract
allergic reaction
anaphylactic shock
inflammation
neurotransmission
what is another name for H1 antagonists?
antihistamines
H1 receptor blocker
what is a first generation H1 antagonist?
can cross the blood brain barrier as it isn’t ionised at physiological pH
what is a second generation H1 antagonist?
ionised at physiological pH so don’t cross the blood brain barrier very easily
what are the main effects of H1 antagonists?
inhibit histamine induced vasodilation inhibit itch relax contracted bronchioles relax contracted intestinal smooth muscle sedation
what are H1 antagonists used to treat?
pruritis, allergic reaction, anaphylaxis, motion sickness, sedation
what are the adverse effects of H1 antagonists?
CNS depression, antimuscarinic effects (dry mouth), drug tollerance
name a H2 antagonist
ranitidine
what are H2 antagonists used for?
inhibit H2 receptors in parietal cells
used to treat gastric/abdominal ulcers, gastritis and reflux
name a mast cell stabiliser
sodium chromoglycate
what is the mechanism of action of mast cell stabilisers?
inhibit histamine release from mast cells by opening chloride channels and hyperpolarising the cell to prevent degranulation
how are mast cell stabilisers administered?
nebuliser or as eye drops