Sedatives Flashcards
Three alpha-2 adrenergic agonists
Xylazine (longest)
Dexmedetomidine
Detomidine (shortest)
Which of the three main a2 sedatives is used in small animal?
dexmedetomidine
Which two a2 sedatives are available as oral gels?
dexmedetomidine and detomidine
Why is xylazine “special?”
least expensive and the least a2 specific
xylazine in ruminants vs horses
ruminants are TEN TIMES more sensitive
a1
vasoconstriction of blood vessels; also possible agitation and increased locomotor activity (though uncommon)
a2
effects on brain and spinal cord to cause sedation, analgesia, anxiolysis
a2:a1 ratio
Which a2 drug doesn’t have CV effects?
trick question, none of them - they all have marked cardiovascular effects
Cardiovascular Effects of a2 Adrenergic Agonists on the Cardiovascular System (3)
Vasoconstriction
Bradycardia
Decreased cardiac output
Biphasic Response of a2 Sedatives
Phase 1 = increase BP and bradycardia (d/t vasoconstriction from a1) (peripheral effects)
Phase 2 = return to normal/decrease BP as drug dissociates (central effects)
Why do both phases of a2 result in bradycardia?
Phase 1 = baroreflex
Phase 2 = decrease in sympathetic outflow
2nd degree AV block
can be seen in a2 administration
dominant parasympathetic tone
Cardiac Output Equation
CO = SV x HR
Should you use a2 adrenergic agonists in high risk patients - why or why not?
NO, only for healthy patients
SIGNIFICANT decrease in cardiac output so perfusion to organs is reduced
Tidal Volume and a2
TV increases with a2 alone; with other drugs it is a depressant and causes upper airway relaxation
PIMS (pulmonary intravascular macrophages)
unique cell in ruminant lungs activated by a2 agonists, leading to irreversible pulmonary edema and hypoxemia
Effect of a2 on Urine?
MASSIVELY increases urine production (so caution with urinary blockages)
Can you use a2 in diabetic patients?
No, it causes hyperglycemia
a2 and GI system
decreases motility and inc. smooth muscle relaxation (good for colic pain in horses)
atipamezole
reversal agent for a2 agonists that MUST be given IM!!!!
acepromazine
dopamine antagonist, no analgesia
cannot be used in allergy testing
Splenic Sponge Effect of Acepromazine
PCV with decrease by 30-30% due to splenic sequestration
Azaperone (oink)
pig acepromazine (mainly used in Europe or for elephants)
Can diazepam be mixed with other drugs? Why or why not?
no - it’s lipid soluble so it is very oily (use midazolam if wanting to mix in a benzo)
Benzodiazepine MOA
GABAa agonist
Flumenazil
benzodiazepine antagonist
Trazadone MOA
serotonin receptor antagonist and re-uptake inhibitor (SARI)
yohimbine
an a2 reversal that isn’t used much anymore
