Unit 2 - Drug Therapy of Inflammation Flashcards
what are the three distinct phases of the inflammatory response?
- acute transient phase, characterized by local vasodilation and increased capillary permeability
- delayed, subacute phase, most prominently characterized by infiltration of leukocytes and phagocytic cells
- chronic proliferative phase, in which tissue degeneration and necrosis occur
what is histamine? what does it do?
autacoid amine made from histidine and stored in mast cells and basophils in many tissues in the body
- released from storage sites in response to injury and Ag
- mediator of immediate (type I) allergic reactions
- acute inflammatory response actions:
- -locally increases blood flow by capillary dilation
- -causes edema by increasing post-capillary venule (PCV) permeability
what are kinins? what do they do?
two related peptides (bradykinin and kallidin) formed from plasma globulins (kinnogens) by kallikreins in blood or in tissues at sites of injury, allergic reaction, viral infections, etc.
- kallikreins released from tissues or activated by clotting factors in plasma
- kinins have:
- -acute effects (pain) due to excitation of primary sensory neurons
- -chronic effects due to capillary dilation, increase in PVC permeability, and activation of arachidonic acid release through stimulation of PLA2 (similar to histamine, except chronic)
what are cytokines? what are the major players?
polypeptides that orchestrate inflammatory process and defense mechanisms in general
- released from lymphoid and non-lymphoid cells, and have multiple actions
- major players are IL-1, IL-8, TNF, and chemokines
what is IL-1? where is it made most? what does it do?
cytokine made particularly by macrophages
- induces inflammatory response
- -increases eicosanoid synthesizing enzymes, collagenase, and adhesion molecule expression
- regulates B and T cells
- induces fever due to action on brain (endogenous pyrogen)
what is IL-8?
powerful chemotactic agents
what does TNF do?
regulates production of other cytokines and induces fibrosis and tissue catabolism
what are eicosanoids? what do they do?
metabolites of arachidonic acid that play central and complex role in inflammation
- released from phospholipids of cell membrane in response to mechanical or chemical injury or agonists that activate PLA2 or diacylglycerol lipase
- AA is metabolized by either lipoxygenase (makes leukotrienes) or cyclooxygenase (makes prostagladins, prostacyclins, and thromboxanes)
describe COX-1
cyclooxygenase (makes prostaglandins, prostacyclins, and thromboxanes) produced constitutively in all tissues
- gastric cytoprotection
- platelet aggregation
- renal blood flow autoregulation
- initiation of parturition
describe COX-2
induced during inflammation
-produces prostaglandins at the sites of inflammation and/or tissue damage
what is the origin of
- histimine
- kinins
- cytokines
- eicosanoids
- mast cells, basophils
- kinin system (kininogen)
- primarily lymphoid cells
- lymphoid and non-lymphoid cells
what are the general actions of
- histamine
- kinins
- cytokines
- eicosanoids
- capillary dilation, increase in venule permeability, sensitization
- as above; effects more chronic than histamine
- immunoregulation, inflammation, fever, chemotaxis, tissue catabolism, induction of COX-2, etc.
- vasodilation, increase venule permeability, sensitization, contraction/relaxation, etc.
what are the primary goals of treating patients with inflammation?
- relief of pain (presenting symptom and major continuing complaint of the patient)
- slowing or (in theory) arrest of tissue damaging process
what is the general mechanism of NSAIDs?
inhibit COX enzymes (thus inhibiting synthesis of prostaglandins, prostacyclins, and thromboxanes, but NOT leukotrienes)
explain the chemistry and pharmacokinetics of aspirin (salicylates)
- pKa = 3.5; ester of acetic acid that can acetylate proteins, thus irreversibly blocking synthesis of eicosanoids by acetylating COX-1/2
- orally administered aspirin is rapidly absorbed by passive diffusion from stomach (non-ionized) and upper SI (ionized) yielded peak plasma level within 1-2 hours
- liver is principal site for biotransformation of salicylates by microsomal and mitochondrial enzymes
- aspirin is first hydrolyzed to salicylic acid and then converted to metabolites that are excreted in urine
- cannot acetylate COX-1/2, but can still reversibly inhibit
what are the pharmacological effects of aspirin?
- antiinflammatory effects
- analgesic effects
- antipyretic effects
- antiplatelet effects
how do aspirin anti-inflammatory effects work?
inhibit eicosanoid formation and thus vasodilation, PCV permeability, luekocyte chemotaxis, etc.
- reduces inflammation in joint tissues and surrounding structures
- much higher dose needed VS analgesia
- treats symptosm of rheumatic and CT disorders
how do aspirin analgesic effects work?
inhibition of eicosanoid-induced sentization of pain receptors (indirectly antagonizes effects of histamine, kinins, etc.) and transmission to relay neurons in dorsal horn
- frequently combined with codeine or other narcotic analgesics to obtain more pain relief
- alleviates pain such as headache, myalgia, arthralgia, dysmenorrhea
- not effective in alleviating visceral pain (acute abdomen, renal colic, pericarditis)