Anti-Inflammatory Drugs Flashcards
(42 cards)
What is an inflammatory response?
A short term, acute response that is defensive and quickly resolved.
What does the inflammatory response involve?
- Acute microvascular changes
- Release of inflammatory mediators
- Accumulation of inflammatory cells
- Repair and healing
What are the common inflammatory mediators in acute inflammation?
-Histamine
-Bradykinin
-Nitric oxide
-Eicosanoid
-Neuropeptides
What are the arterioles and venules involved in?
Arterioles = blood pressure changes
Venule = Oedema formation and cell accumulation
What happens in the acute inflammatory response?
Microvascular effects are triggered from a variety of cells and plasma in and around these vessels
Inflammatory mediators (also known as local hormones) released
Is histamine preformed?
Yes
Preformed = already stored in cells of the body (mast cells) ready to be released
What is histamine formed from and what is its major source?
Histamine formed from histidine
Major source: mast cells & basophils
When is histamine released?
Released in allergic/ hypersensitivity (IgE) responses.
What do H1 receptors mediate?
Increased blood flow,
increased microvascular permeability,
itch
What 2 categories do H1 antagonists fall into?
Sedating: chlorpheniramine, diphenhydramine, promethazine
Non-sedating ones preferred today: loratadine, cetirizine, terfenadine, astemizole
Sedating = causes drowsiness
Non-sedating = less drowsiness
Give some examples of conditions where anti-histamines are used.
Allergy,
allergic rhinitis,
urticaria,
hay fever
skin irritations
Which sensory nerves are the pain fibres?
C and Aδ fibres
What are the roles of the C and Aδ fibres?
They have a dual role:
They transmit sensory information to CNS/initiate reflexes nociception- pain and itch
They release neuropeptides - many including substance P, CGRP and VIP (alleviate migraine)
What does the stimulation of the sensory nerves include?
Mechanical (pressure)
Temperature (cold & heat)
Chemical (mediators & capsaicin)
What is the conducting velocity of this subset of sensory nerves?
0.5 m/s (so it’s slow as it’s half the speed of normal C fibres)
What distinct subset of sensory nerves mediate itch?
~5% of afferent C fibres in skin
They respond to histamine but are insensitive to mechanical stimuli
What are good anti-itch agents?
Anti-histamines are effective
Local anaesthetics can also be used to reduce pain/itch of course
What is arachidonic acid?
the key to making proinflammatory cytokines & a 20 carbon polyunsaturated fatty acid
How can arachidonic acid be metabolised?
Either via the cyclo-oxygenase pathway to prostaglandins & thromboxanes
OR
via the lipoxygenase pathway to leukotrienes
What are eicosanoids?
The name given to the arachadonic acid metabolites i.e.
prostaglandins, thromboxanes, leukotrienes
How are the different eicosanoids synthesised and what are their roles?
Prostaglandins = Synthesised by the cyclo-oxygenate enzymes
leukotrienes = synthesised by 5-lipoxygenase
What does the cyclo-oxygenase pathway look like?
- Arachidonic acid = 4 double bonds, poly unsaturated fatty acid
- Oxygen is inserted to mediate the cyclic endoperoxides (PGG2 and PGH2)
3.Both unstable with the oxygen inserted, to break up the double bonds.
4.They are metabolised via the enzyme relevant to that tissue
What inhibits arachidonic acid metabolism via cyclo-oxygenase?
NSAIDs (which leaves the lipoxygenase enzyme unhindered to carry on as normal)
What are the characteristics of NSAIDs?
They inhibit prostaglandin generation & they’re analgesic (alleviate pain)
anti-inflammatory, reduce fever but can enhance bleeding