CNS drugs Flashcards
1
Q
what makes up the CNS?
A
- brain
- spinal cord
2
Q
what are the two basic functions of the CNS?
A
- sensory reception
- motor reaction
3
Q
how does the CNS function?
A
- receives stimuli from both insides and outside the body
- collects the stimuli and interprets them
- stimulates tissues, by means of motor neurons, to carry out appropriate actions
4
Q
what is the basic working unit of the sensory and motor portions of the CNS?
A
the neuron
5
Q
what do neurons do?
A
- sens changes that prompt them to generate and conduct electrical impulses
6
Q
what are the two types of junctions
A
- synapse
- neuro-effector junction
7
Q
what is a synapse?
A
the junction between two neurons
8
Q
what is a neuro-effector junction?
A
the junction between a neuron and the muscle or gland cell, where the effect is produced
9
Q
how do drugs affect the CNS?
A
mimic or block the CNS neurotransmitters
10
Q
define: sedative
A
produce slight CNS depression without inducing sleep
11
Q
define: tranquilizers
A
- alter behavioural patterns, without inducing sleep
- produces some sedation
12
Q
define: non-narcotic analgesics
A
decrease pain, without inducing sleep
13
Q
define: narcotic analgesics
A
decrease or block pain, possibly inducing sleep
14
Q
define: hypnotics
A
depresses CNS activity to produce a state similar to sleep
15
Q
define: general anesthetic
A
causes a systemic loss of sensation, without accompanying (inducing) sleep
16
Q
define: local anesthetic
A
causes a local loss of sensation, without sleep
17
Q
define: stimulants
A
- increase specific areas of CNS activity, such as the respiratory center
18
Q
Phenothiazine derivatives
A
- class of sedative and tranquilizer (drugs used for CNS)
- is a mild sedative, animals are more docile
- antiemetic (inhibits stimulation of the emetic center of the brain, good for motion sickness)
- maintains heart rhythms
- helps with agitated behavior from itching
- synergistic effect with narcotics, analgesics, and anesthetics (makes it effective as a pre-anesthetic medication in dogs, cats, and horses)
- no analgesia (no loss of pain)
19
Q
adverse effects of phenothiazine derivatives
A
- possible permanent prolapsed penis (DONT’T USE IN STALLIONS)
- some stimuli can cause adrenaline to override the drug’s effectiveness
- MAY LOWER SEIZURE THRESHOLD
- causes vasodilation (contraindicated in shock)
- metabolized by the liver and excreted by the kidney ( contraindicated in patients with hepatic or cardiac disease)
- prolapses the 3rd eye
- hypertension
- give to fairly healthy animals
might make fearful animals snap
20
Q
how are phenothiazine derivatives administered?
A
- IV or IM if an anesthetic premedication
- oral tablet for sedative and antiemetic (good for travel)
21
Q
Acepromazine
A
- a type of Phenothiazine derivative
- most potent and most popular
- Pre-med or chill-out drug
- mild sedation, no analgesia
- antiemetic
- antidysrhythmic
22
Q
list the Alpha-2 Adrenergic agonists (CNS)
A
Xylazine
Detomidine
Dexmedetomidine
Type of sedative and tranquilizers
23
Q
Alpha- 2 Adrenergic Agonists (CNS)
A
- stimulates presynaptic alpha-2 adrenoceptors in the CNS and PNS ( decreases norepinephrine release)
- stimulate the receptors in the CNS, heart, and blood vessels
- used for sedation, pre-anesthetic, short-term mild analgesic
good for: sedation, pre-anesthetic, short-term mild analgesia, and emesis (in felines) - avoid in cardiac, hepatic, renal, seizure, and debilitated patients
- ONLY USE IN HEALTHY PATIENTS
24
Q
adverse effects of alpha-2 adrenergic agonists (CNS)
A
- muscle tremors
- bradycardia
- decreased or increased BP
-respiratory depression - sensitivity to loud noises
- polyuria in cats
25
Xylazine
- an Alpha-2 Adrenergic Agonist
- used in: dogs, cats, horses, and cattle
- sedation and analgesic
- The period of analgesia is shorter than that of sedation
- acts on CNS to produce: muscle relaxation, decreased respiration, decreased HR, arrhythmias, bloat, and abort late-stage pregnancies
clinical use: pre-anesthetic, chemical restraint, vomiting cats, anesthetic induction when combined with ketamine
reversal agents: Yohimbine and Tolazoline
- Cattle are very sensitive to this (1/10th of the equine dose)
26
Xylazine reversal agents
- Yohimbine
- Tolazoline
- they block the CNS receptors stimulated by Xylazine
27
what drug are cattle very sensitive to?
Xylazine
28
Detomidine
- an Alpha-2 Adrenergic Agonist
- a sedative with potent analgesic activity (dose dependent effects)
- IV or IM
- chemical restraint and pain relief during diagnostic or minor surgical procedures
- can cause MARKED reflex bradycardia and transient hypertension
- when you reverse the drug, you also reverse the pain control
used in HORSES
29
Dexmedetomidine
- Alpha-2 Adrenergic agonist
- sedative and analgesic
- often used as pre-med or post-op
- adverse effects: reflex bradycardia, decreased respiration rate, and transient hypertension during use
- commonly combined with opioids
Reversal agent: Atipamezole (1:1 ratio), administer IM post-procedure for rapid reversal
30
what is the reversal agent for dexmedetomidine
atipamezole (1:1 ratio)
31
list the benzodiazepine derivative drugs
- diazepam
- Midazolam Hydrochloride
- Azaperone
32
Benzodiazepines
- class of CNS drugs
- centrally acting muscle relaxants
- enhance the activity of the CNS neurotransmitters (GABA agonists)
- commonly used in combination with other drugs (ketamine) for IV induction (diazepam suppresses excitatory and hallucinatory effects of ketamine and gives muscle relaxation
33
what are Benzodiazepine drugs used as? (5)
- sedatives
- anticonvulsants
- muscle relaxants
- appetite stimulants ( cats)
- anti-anxiety
34
Diazepam
- a benzodiazepine
- decreases anxiety while producing mild sedation
- good anticonvulsant
- good muscles relaxant
- common clinical use: induction agent, seizure preventative
- Slow IV injection
- used PO for behavior problems and appetite stimulation (in cats)
35
Midazolam Hydrochloride
- a benzodiazepine
- antianxiolytic
- amnestic
- hypnotic
- anticonvulsant
- skeletal muscle relaxant
- sedative
- IM or slow IV
- commonly combined (especially with opioids)
- reversal agent: Flumazenil (a benzodiazepine antagonist)
36
what is the reversal agent for Midazolam Hydrochloride?
Flumazenil
37
Azaperone
- a benzodiazepine
- designed for pigs
- sedative-tranquilizer
- animal remain conscious but is indifferent to their surroundings
- fast onset
- used in pigs for aggression problems, cross-fostering, maternal aggression
38
CNS Analgesic
narcotics and non-narcotics acting on the CNS
39
Opioid analgesics
- are a category of drugs derived from the opium poppy alkaloids
- opium receptors are all throughout the body but act primarily on the receptors in the brain and spinal cord
- responses varry on the receptor acted upon
- drugs can be agonists, partial agonists, agonist-antagonists, or antagonists
40
what are the 4 types of opioid receptors
Mu
Kappa
Sigma
Delta
can use the drugs in the same group inter changably
41
Mu
- most potent opioid receptor
Drug action:
- analgesia
- euphoria
- respiratory depression
- decrease GIT mobility
- physical dependence
42
Kappa
- second most opioid receptor
drug action:
- analgesia
- sedation
- anticonvulsant arrfct
- dysphoria
- depression
- hallucinations
43
Sigma
third most potent opioid receptor
drug action
- vocalization
- hallucinations
44
Delta
least (4th) effective opioid receptor
drug action:
- analgesia
- antidepressant
- physical dependence
45
what are opioids most commonly used as? (5)
- analgesics
- pre-medications
- neuroleptics
- antitussives
- sedatives
46
use caution with opioids at low doses when the following is present:
- hepatic disease
- renal disease
- respiratory disease
- hypothyroidism
- hypoadrenocorticism
- constipation
- geriatric patients
47
what are the adverse effects of opioids (5)
- nausea (vomiting)
- physical dependence
- urinary retention
- dysphoria
- hyperesthesia (heightened sensitivity to stimuli)
48
Morphine
- the OG opioid
- synthetic narcotic analgesic
- used for: acute pain, pre-anesthetic, antitussive, antidiarrheal
- IV, IM, SQ, or rectally
- adverse effects: vomiting, respiratory depression (this is how overdoses happen), hyperexcitability in cats pigs and horses, cerebral hemorrhage and edema with head injuries (due to further increase in respiratory depression)
49
Fentanyl
- opioid (narcotic) analgesic
- 100x more potent than morphine
- primarily used for analgesia
- short duration
- IM, SQ, CRI, transdermal patch
50
Butorphanol
- opioid (narcotic) analgesic
- the garbage of opioids
- not considered a narcotic but still needs to be locked up
- pre and post-op analgesia in small animal medicine
- mild analgesia for a short duration
- minimal depression of the heart and respiratory system, not dose-related
- has a ceiling effect
- tends to reverse some of the other opioids
51
Oxymorphone
- narcotic analgesic
- 8-10x stronger than morphine
- used to: analgesic (used alone), neuroleptanalgesia (used with tranquilizer)
- side effects: respiratory depression, reduced heart rate (atropine can be used to prevent bradycardia)
52
meperidine
- opioid analgesic
- synthetic narcotic
- compared to morphine: 1/10th the analgesic effect, less CNS and respiratory depression, less prone to cause excitement in cats and horses, shorter duration
- some antispasmodic activity
- common pre-anesthetic when combined with acepromazine and atropine
53
hydromorphone
- opioid analgesic
- semi-synthetic narcotic analgesic
- 5x more potent than morphine
- used for: analgesia for moderate to severe pain, sedation, adjunct for pre-anesthesia drug combinations
compared to oxymorphone: similar potency, shorter duration of activity, similar adverse effect profile
- often causes nausea (especially IV)
54
Buprenorphine Hydrochloride
- opioid analgesic
- synthetic narcotic
- partial agonist
- fewer negative side effects
- used for: analgesia of moderate pain (cats and dogs), neuroleptanalgesia (horses)
- lasts longer than most narcotics (6-12 hours)
- may alter heart rate and respiration rate
- preferred opioid for cats because less dysphoria
55
Tramadol
- narcotic analgesics
- oral synthetic codine-analogue and SNRI (serotonin norepinephrine reuptake inhibitor)
- synthetic narcotic
- analgesia and antitussive
- less CNS depression
- used in cats and dogs
- chronic pain
56
how do dogs metabolize Tramadol
- they lack the enzyme necessary to metabolize it to codeine-like metabolite
- therefore its action in canines only mimics that of an SNRI (less analgesia and longer onset of action)
57
Naloxone
- reverses negative opioid-induced side effects (respiratory depression, dysphoria)
- can give one drop under the tongue in neonates after a caesarian section
- may reverse or partially reverse the opioid
58
describe a local anesthetic
- loss of sensation from a specific area
- most often by blocking nerve impulse transmission
59
what is general anesthesia
- the loss of all sensation (an overdose is a euthanasia)
60
what are the effects of local anesthetics?
- decrease or eliminate pain perception from localized, peripheral areas by either decreasing temperature in that area or decreasing nerve transmission from the area
61
anesthetic induction/ injectable anesthetics:
- bring about a state of general anesthesia via injection
- have limited duration (topped up or CRI, or switched to inhalant)
62
inhalant anesthetics
- maintain general anesthetics for a prolonged period via gas anesthetic agents via endotracheal tube (safest)
63
Lidocaine
- local anesthetic
- cats are sensitive to it
- very common
- can be used with or without epinephrine
- if given SQ is an antidysrhythmic
64
list the local anesthetics
- lidocaine
- mepivacaine
- bupivacaine
(-Caine)
65
mepivacaine
- local anesthetic
- horses and dogs
- slower onset than lidocaine
- longer duration of action than lidocaine
66
Bupivacaine
- local anesthetic
- 2-4x more potent than lidocaine
- common in dental procedures because small volumes are needed
- provides up to 12 hours of effect
- SQ: blocks nerves
- ID decreases pain sensation at the surface
- can be combined with morphine for epidural anesthesia
67
what MUST you do before giving a local anesthetic drug?
calculate the toxic dose
68
disadvantages of injectable anesthetic drugs (3)
- some have a short duration
- some don't have reversals
- not immediately eliminated
69
what is general anesthesia?
- a state of CNS produced by drugs
- characterized by: unconsciousness, reduced reflexes, loss of memory, loss of pain sensation, relaxation of skeletal muscles
70
what are injectable anesthetics used as?
inducting agents for general anesthesia
71
what are inhalant anesthetics used for?
maintaining anesthesia
72
describe barbituates
- not a narcotic
- can be addictive (so are controlled)
- interacts with CNS, inhibits GABA receptors
- mainly used as: anticonvulsants, anesthetics, euthanasia solutions
- very lipophilic (crosses the blood-brain barrier) (contraindicated in sighthounds due to lack of body fat)
- contraindicated in thin or overweight animals
- highly protein-bound in plasma (reduced amounts in patients with hypoproteinemia)
73
what are barbituates commonly used as?
- anticonvulsants
- anesthetics
- euthanasia solutions
74
what is contraindicated for sighthounds?
barbituates
- due to their lack of body fat
75
Thiopental sodium
- Barbiturate
- particularly irritating to tissues (cause tissue sloughing)
- ultra short-acting
- unavailable in Canada
- induction of general anesthesia
- crosses BBB producing a depressant effect
- is rapidly redistributed to other body tissues because of high lipid solubility
- may need multiple doses
- may have prolonged recovery
76
Phenobarbital sodium
- barbiturate
- considered long-acting
- often administered PO as an anticonvulsant
- not generally used as an anesthetic agent
77
Euthanasia solutions
- barbiturates
- often contain pentobarbital or phenytoin
- highly controlled
78
Dissociative agents
(acrylcyclohexamine drugs)
- act by depressing the CNS and creating a feeling of dissociation
- CNS stimulation
- exaggerated reflexes
- increased muscle tone
- analgesia
- amnesia
- hallucinations
- agitation
- avoid in patients with: head trauma, seizure disorders, hypertension, cardiac disease, hepatic disease, renal disease, glaucoma
79
ketamine
- dissociative agent
- most common drug in this group
- used in all sp (arrived in humans and cats)
- poor analgesia
- poor muscle relaxation
- may cause excitation or convulsion during recovery
- patients typically pre-treated with atropine to decrease the excess salivation (or an anticholinergic agent)
- may be disoriented for hours
80
what is ketamine combined with in dogs
diazepam
81
what is ketamine combined with in horses
xylazine
82
what is ketamine combined with in cats
acepromazine or diazepram
83
Propofol
- phenol group
- ultra-short acting (5-7 min)
- noncumulative
- rapid recovery (complete in 30 min)
- muscle relaxation
- sedation-hypnosis with IV induction
- limited/ no analgesia
- can top up or give CRI
- no 'hangover' effect
- safe for sighthound
- does not cause sloughing
- this is what Michael Jackson OD on
84
Alfaxalone
- Neurosteroid
- one of the newest induction drugs
- IV or IV
- extremely wide safety margin
- fast acting
- non-irritating
- less overall cardiovascular depression
- ultra short-acting
- non-cumulative
- rapid recovery (will recover better if combined with another drug)
- can top up of give CRI, no 'hangover effect'
- safe in sighthounds, c-sections, etc
- transient apnea on induction is similar to propofol
- clear
85
Guaifenesin
- centrally acting muscle relaxant (administered parenteral)
- expectorant (administered PO)
- minimal respiratory and cardiovascular effects
- mainly used in large animals
86
Inhalant anesthetics advantages
1. depth of anesthesia can be altered quickly
2. metabolism is required for excretion (less stress on liver and kidney)
87
list the common inhalant anesthetic drugs
- isoflurane
- nitrous oxide
88
Isoflurane
- most common inhalant anesthetic
- safest
- vary fast induction and recovery
- respiratory depression is dose dependent
- no analgesia
89
Sevoflurane
- inhalant anesthetic
- generalised, reversable depression of the CNS
- similar to isoflurane but: faster induction and recovery, less odour, less cardiovascular and respiratory depression
- expensive
90
Nitrous oxide
- inhalant anesthetic
- laughing gas
- avian anesthesia
- use 2:1 ratio of oxygen
- does not produce adequate surgical anesthesia
- to prevent diffusion hypoxia the patient must be oxygenated 5 minutes post-procedure
91
what is diffusion hypoxia?
nitrous oxide leaves body tissues rapidly and occupies alveoli- displacing oxygen
92
List the anticonvulsants
- diazepam
- potassium bromide
- levetiracetam
- zonisamide
- gabapentin
93
Levetiracetam
- anticonvulsant
- faster acting
- needs to be given TID
94
stimulants
- not common in vet med
- facilitate biochemical reactions of impulse transmission
- ones that act on the medulla are most common
- respiratory analeptics
95
Doxapram
- stimulant
- common respiratory stimulant
- unavailable in Canada
- used in cats, dogs, and horses
- IV or sublingual
- rapid and short-acting
- increases the depth of respiration
- thought to increase the demand for oxygen by the myocardial cells
96
Neuromuscular blocking drugs
- drugs that interfere with neuromuscular transmission
- acts to paralyze the respiratory muscles (needs mechanical ventilation)
- facilitate intubation and open chest sx
- does not provide analgesia
- preferably administered under supervision of an anesthesiologist
97
Succhinylcholine
- neuromuscular blocking drug
- depolarizing effects
98
Atracurium
- neuromuscular blocking drug
- non- depolarising
99
types of behavioral pharmacotherapies
1. behaviour modifiers
2. SSRI behaviour modifiers
3. Tricyclic behaviour modifiers
100
describe behavior modifiers
- serotonin receptor agonist
- can be effective with one dose
101
list the behavioral modifying drugs
- buspirone
- trazodone
102
list the SSRI behavior modifier drugs
- fluoxetine
- paroxetine
103
list the tricyclic behavior modifiers
amitrityline
104
describe SSRI behavior modifiers
- antidepressants
- serotonin reuptake inhibitor
- takes several doses to weeks to be effective
105
describe tricyclic behavior modifiers
- prevent the re-uptake of norepinephrine and serotonin
- take several doses to weeks to be effective
