anaesthesia 6 - sedatives and tranquilisers 2 Flashcards

0
Q

alpha 2 receptors are mostly what?

A

inhibatory! bind an inhibatory G protein which inhibits cAMP. CAUSE LOWERD CA2+ INFLUX. and lowered neaurotrans. (some excitatory)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

where would you find adrenoreceptors?

A

they bind catecholamines (NA) in the postsynaptic part of the SNS. they are GPCR and are either alpha or beta.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

alpha 2 receptors are where?

A

presynapticcaly - block release of NA. therefore cause sedation effects. (negative feedback)
postsynaptic - cause vasodilation in arteries and veins (peripheral. due to increased camp. ) also found on fat cells, kidney, lipolysis etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

3 classes of alpha 2 agonists? vary how? which is less selective.

A

-imadozoles (clonidine)
-oxazolines
-phenylthylamines. (xylazines)
vary in slectivity for alpha 1 and 2 receptors. xylazine is less selective.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how do imidazoline binding sites work?

A

they are similar to aplha 2 binding sites. bind alpha 2 ligands that are imidazolines (clonidine) or oxazolines but not phenylthyamines. (adrenaline/xylazine)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the effect of alpha 2 agonists on the cns? if dose too high?

A

sedation and anxiolysis due to inhibiton of NA release. non-selective drugs may cause them to be more anxious at high doses.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the effects on the cns of alpha 2 agonists?

A
analgesia + sedation ans anxiolysis. 
analgesia - especially visceral and acts at 3 locations:
-brain
-spinal cord
-peripheral tissues
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

when opioids are not effective in relieveing pain then what could you use? routes?

A

could use alpha 2 agonists - block release of NA. there fore stop pain signals. can give extradural or intrathecal routes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is an anaesthetic sparing effect?

A

means when you use alpha 2 agonists then you can cut down on other drugs. 95% MAC (minimum alveolar concentration) . but if you need it to last long then may need to up it again?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

when are they good for muscle relaxation?

A

alpha 2 agonists are good when used prior to ketamine anaesthesia.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the importance of the species variations with regards to alpha 2 agonists?

A

some are much more sensitive. eg. cattle are 10x more sensitive to xylazine than horses. pigs are relatively resistant!!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

wht are the effects on the cvs?

A

vascular tone, bp and hr.
alpha 2 effects and also non0selective alpha 1 receptors.
vasoconstriction and hypertension (alpha 2)
vagus and bradycardia response (alpha 1) - slowed HR. due to baroreceptors - sense high pressure blood. this leads to hypotension and so hr is lowered and

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the effects of alpha 2 agonists on respiration? main effect on sheep. ?

A

species and agent varation
mild depression of ventilatroy response
marked increase in airway resistance with xylazine in sheep.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

effects on the GIT?

A

vomiting, and reduced motility. lowered salivation and reduced gastric secretion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

effecst on the endocrine system?

A

inhibit ADH - diuresis
inhibit insulin - hyperglycaemia
induce growth hormone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

effect son the urogenital system?

A

uterine contraction. dont use xylazine if pregnant!!!

16
Q

also does what to platelets?

A

induces aggregation - increase clotting.

17
Q

xylazine? alpha 2 agonists. cows? horses? zoo animals? 24 hour rule?

A

clear 2% solution for inj in cattle as they are sensitive. used for pre-med prior to ketamine. barbituate induction.

10% in horses solution

or dry substance white powder for inj in horse/zoo animal.

+ a range of doses given for standing cattle but 24 hour rule - do not re-dose if inadequate
9wait 24 hours then start again)

18
Q

xylazine in horses? cat/dog? when dont you use in cattle? excreted? good for horses? muscle relaxant?

A

i/v. duration of 20 minutes.

cat /dog? - licensed pre-med but reduce barbituate by 50%. (sparing)

iin cattle not in last month of pregnancy as causes uterus contraction.

good analgesia in colic and muscle relaxant before ketamine. excreted in urine.

19
Q

detomidine? - alpha 2 agonist. in cattle and horses? what doe i do if pregnant?

A

clear liquid 10mg/ml. sedative/analgesic in horses.
used with opoids to improve sedation. pre-med for ketamine
i/m or i/v .
more potent than xylazine.
+ cattle it is equipotent!!
longer duration
more ataxia
slow electrical activity in uterus of preg cow.

20
Q

romifidine? ‘sedivet’ what doesnt this one do? why is this good?

A

liquid 10mg/ml. sedative/aanalgesix in horses or pre-med.
i/v use
less ataxia
longer duration (3hours) not a muscle relaxant! - therefore can be used for clipping etc.

21
Q

medetomidine? routes? which species? highly selective for? whenwouldnt you use it? what can reverse?

A

im, iv, sc, inj in dog/cat.
1mg/ml

potent and highly selective in alpha 2
duration up to 3 hours.
anaesthetic sparing agent.
dont use if cv disease. met in liver and excreted by kidney. vomit less common!

antisedan can reverse!

22
Q

dexmedetomidine? for use in? effect? how do you dose? why is this a problem?

A

dog/cat. very ptoent. antiarrynthmic agent. short duration.

dose according to body surface so this is a problem if they are fat.

23
Q

alpha 2 antagonists? eg? for use in?

A

antisedan. dog/cat given i/m. in a helathy animal good for short duration procedures.