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33 Cards in this Set
- Front
- Back
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Alpha-2 agonists
-traditional use in vet med |
-sedatives
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Alpha-2 agonists
-MOA for analgesia |
-certain subtypes help with analgesia
-all current agonists bind to all receptor subtypes |
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Alpha-2 receptors
-MOA |
-bind epinephrine and norepinephrine
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Alpha-2 postsynaptic receptor
-function |
-bind neurotransmitter to exert an action
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Alpha-2 Presynaptic receptor
-function |
-diminish further release of norepinephrine
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Alpha-2 receptor’s function on non-adrenergic nerves
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Modulate release of other neurotransmitters
-acetylcholine -neuropeptides |
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Analgesia mediated by Alpha-2 agonists due to:
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-action at the brain and spinal cord
-action at the adrenergic nerve (sympathetic) and other neurons -presynaptic and postsynaptic action |
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Spinal cord analgesia occurs where?
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-dorsal horn
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Location of Alpha-2 receptors in the dorsal horn for analgesia
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-primary afferent C fibers
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Predominant neurotransmitter for nociception in the dorsal horn
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-Substance P
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Alpha-2 receptors also located where in the dorsal horn?
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-spino-thalamic projection neurons
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Effect of Alpha-2 receptors of spino-thalamic projection neurons
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-hyperpolarize nerves to inhibit ascending nociceptive transmission
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Alpha-2 agonist
-sites of supraspinal analgesia |
-activation of a descending inhibitory pathway
-decreased release of norepinephrine from the brainstem -“disinhibition” of other descending pathways (opioid inhibitory system) |
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Alpha-2 agonist
-clinical use |
-significant, dose-dependent sedation (most spp.)
-analgesia with side-effects on other body systems |
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Alpha-2 agonist
-cardiovascular side-effects |
-increased vascular resistance (α-1 & α-2 effects)
-decreased HR -decreased CO |
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Alpha-2 agonist
-respiratory side-effects |
-respiratory depression
-decreased arterial oxygen *dependent on dose and spp. |
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Alpha-2 agonist
-GI side-effects |
-vomiting
-decreased GI motility |
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Alpha-2 agonist
-hormonal effects |
-decreased insulin release
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Alpha-2 agonists
-urinary system effects |
-increased urine output
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Alpha-2 agonist drugs used clinically
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-xylazine
-dexmedetomidine -detomidine -romifidine |
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Xylazine
-predominant use |
-large animals
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Xylazine
-characteristics |
-least selective Alpha-2 (lots of Alpha-1 activity)
-short duration sedation and analgesia -local anesthetic effect (can be used epidurally) |
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Detomidine
-predominant use |
-large animals
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Detomidine
-characteristics |
-higher potency and longer duration than xylazine
-mostly a sedative -profound analgesia -NO local anesthetic effect -can be used epidurally with morphine -used frequently with opioids (butorphanol) |
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Dexmedetomidine
-predominant use |
-small animals
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Dexmedetomidine
-characteristics |
-alpha-2 specific
-potent sedative effects -can combine with opioids at lower doses -can use as CRI for analgesic and sedative effects |
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NSAIDs
-MOA |
-direct inhibition of COX enzymes
(mostly COX-2, but block both 1 & 2) |
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COX enzyme
-function |
convert arachidonic acid to:
-prostaglandins -thromboxanes -leukotrienes |
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Explain the pathogenesis of hyperalgesia
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-injury causes the release of chemicals from tissues and infiltrating cells
--resulting inflammation causes an enhanced response to stimuli |
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NSAIDs
-when do you want to ideally administer the drug |
-before the inflammation starts (but many things to consider)
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NSAID
-side-effects |
-renal
-GI (decreased perfusion) -coagulation |
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NSAIDs
-contraindications |
-patients with pre-existing hypovolemia or hypotension, or the potential for hypovolemia/hypotension
-don’t give prior to surgery due to hypotension from anesthesia |
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What is necessary for the autoregulation of renal blood flow during hypotension?
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-prostaglandins
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