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276591
Sedatives
Description
Doctorate Anaesthesia Mind Map on Sedatives, created by melian.yates on 14/10/2013.
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anaesthesia
anaesthesia
doctorate
Mind Map by
melian.yates
, updated more than 1 year ago
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Created by
melian.yates
about 11 years ago
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Resource summary
Sedatives
Phenothiazines
Mechanism
Dopamine Antagonism
CNS
Anxiolytic
Neuroleptic
Tranquiliser
Antiemetic
Mild sedative, if dose is increased, will just prolong level of sedation & increase side effects
NO Analgesic properties
Except Methotrimeprazine (small animal immobilon)
Side Effects/ Toxicity
Basal Ganglia
Movement disorders (Chronic use - humans)
Pituitary Gland
Increases Prolactin release (Chronic use - humans)
CVS
Blocks alpha 1 - adrenoreceptors
Vasodilation & Hypotension
Can promote hypothermia
Anti-arrhythmic action
GIT
Antispasmodic action on gut
AntiHistamine (receptor blockade)
AntiMuscarinic (receptor blockade)
5 - HT blockade
Potency of action dependent on the type of side chain attached to the N atom of the Phenothiazide ring
R1 = Propylamine
Increases Sedation
R1 = Piperadine
Anticholinergic activity
R1 = Piperazine
Less Sedative and Less Anticholinergic
Drugs
Acepromazine (ACP)
Used extensively (Pre-anaesthetic)
Oral tablet (Dogs & Cats), Injection (Small & Large animals), Gel (Horses)
Absorption
Oral bioavailabilty: 20 - 55%
Onset: IM: 20 min, I/V: 5 min
Lower end of dose range used I/V
Combined w/ Opiods (Boxers and small animals w/ CV compromise)
IM Preferred
I/V: Given slowly to avoid vasodilaton and hypotension
Metabolism
Liver
Distribution
t 1/2 = 4 - 6hrs
Excretion
Conjugated & Non-conjugated metabolites => Urine
Low dose: Behavior; High dose: sedation
Effective on young, anxious animals
Potentiates action of other drugs
Opiods
General Anaesthetics (Barbituates)
Local Anaesthetics
May lower the threshold for epileptiform sezures
Anticonvulsant properties
Potent Spasmolytic
Tx of Laminitis in Horses
Propionylpromazine
Chlorpromazine
Less potent, longer duration, unreliable in horses (excitement)
Promazine
Better sedation, fewer side effects than Chlorpromazine
Methotrimeprazine
Small animal Immobilin
Potent Analgesic
Promethazine
Irritant, Deep IM, Potent Antihistamine
Butyrophenoenes
CNS
Dopamine Antagonism
Sedative Action
Potent Antiemetic
Side Effects
Hallucinations, Agitation (Humans)
CVS
Vasodilation
Hypotension
Drugs
Azaperone
Sedate/ modify behavior
Pigs (Licensed)
Tx of aggression
Transport stress
Obsteric conditions
Premed for local and General Anaesthesia
Potentiates Anaesthetic Agents
Slight fall in BP
Absoprtion
Deep IM injection
Behind ear (Pigs)
Leave undisturbed for 20 min
Distribution
t 1/2: 2-3 hrs
Fluanisone
Hypnorm: Used in combination w/ Fentanyl
Neurolept Anaesthesia
Mice, rats, rabbits & guinea pigs
Droperidol
Potent Neuroleptic
t 1/2: 6 - 8 hrs
Potent Antiemetic
Used in combination w/ Fentanyl
Neuroleptanalgesia
Benzodiazepines
Mechanism
Potentiation of GABA mediated Inhibition
CNS
Primarily Anxiolytic action
Muscle relaxation
Anticonvulsant
Little sedation in young, healthy animals
CVS/ Resp.
Minimal depression
Drug interactions
Synergistic effects with other central depressants
Ex. Barbituates, Antihistamines and alcohol
Metabolism
Liver => Active metabolites
Toxicity (Chronic use)
Cognitive impairment
Tolerance
Dependence
Drugs
Diazepam (Valium)
Absorption
Insoluble in H2O
Dissolved in propylene glycol
IV or Oral
Rapid Onset
Long acting
Metabolism
Liver
Does not induce hepatic enzyme systems
Severe hepatic dysfunction, prolonged duration of action possible
Distribution
t 1/2: 20 - 40hrs
95% Protein bound
Side Effects
Pain on injection
Thrombophlebitis
Cardiac Arrhythmias
Uses
To control status epilepticus
Stimulate appetite
+ Ketamine (Horses and Small animals): Induce and Maintain Anaesthesia
+ Hypnorm (small mammals): Anaesthesia w/ muscle relaxation
Midazolam
Does NOT cause Thrmbophlebitis
Absorption
H2O soluble
IV, IM, Oral
Distribution
Short duration
t 1/2: Cats: 2 hr
Climazolam
Horses: Maintain Anaesthesia + Ketamine
Tolezepam
+ Tiletamine (Dissociative Anaesthetic
Benzodiazepine Antagonists
No intrinsic efficacy; Competetive Anatagonist
Flumazenil
Humans
Dogs, Cattle, Sheep: Antagonism of Diazepam/Midazolam sedation
Has some Inverse Agonist Activity
Sarmazenil
Antagonize Midazolam, when used in combination w/ Ketamine to maintain Anaesthesia in Horses
Inverse Agonists
Act @ GABA receptor
CLOSE the Cl- channel
Causes the neuron to become vulnerable to excitation
May promote convulsions
Alpha 2 - Agonists
Vary in Selectivity for Alpha 1 and Alpha 2 receptors
Some also bind Nonadrenergic Imidazoline receptors
Stimulation = Hypotension and Anti-arrhythmic action
Imidazoles
Detomidine
Really expensive
Really potent
Equipotent in Horses and Cattle
Absorption
IV or IM
Distribution
Longer duration
t 1/2: 1 - 2 hrs (Horses)
Urogenital
Slows uterine electrical activity
Better for pregnant cows
Romifidine
Distribution
Longer duration
t 1/2: up to 3 hrs
CNS
Causes less ataxia in horses
Medetomidine
Dogs, Cats, Exotics & Horses
Absorption
IM, IV or S/C
Distribution
t 1/2: 3 hrs
Very potent & very selective for Aplha 2 receptors
Profound ANaesthetic sparing effect
Max effect on BP w/ low doses
Equal mixtture of 2 enantiomers
Dexmedetomidine
Levomedetomidine
Pharmacologically inactive
Dexmedetomidine (Dogs)
Very potent
Greater slectivity for Alpha 2 receptors than Alpha 1
CVS
Antiarrhythmic
Depresses HR
Hypotension
Pale/ blue tinged mucous membranes
Distribution
Highly protein bound: 94%
Doses based on body surface area
Anaesthetic sparing
Reduce dose of induction by 30-60%
Should only be used for procedures < 20 min
Clodine
Oxazolines
Rilmenidine
(DO NOT BIND to imidazoline receptors) Phenylethylamines
Xylazine
Absorption
IM or IV
Cows, Horses: 24 hr rule (before 2nd dose)
Distribution
t 1/2: Species, Route and Dose dependent
Metabolism
Metabolised to multiple products that are excreted in urine
Low selectivity for Alpha 2 receptors
Used in Small and Large animals
CNS
Species differences in sensitivity
Ruminant > Horse/Dog > Pig
CVS
Arrhythmogenic
Unlike modern drugs
Urogenital
Contraction of Uterine smooth muscle
Not licensed for Cows in 3rd trimester => Abortion
CNS
Sedation (Pre-synaptic)
Analgesia
Muscle Relaxation
+ Ketamine
Given intrathecally or Extradurally
CVS
Vasoconstriction
Hypertension
Bradycardia
Due to Vagal reflex (feeback mechansims)
Works well w/ Opiods
Anaesthetic sparing effects (50-95%)
RESP.
Respiratory depression
Reduction in airway resistance
Xylozene (Sheep)
GIT
Vomiting (Some species)
GI motility depressed
Endocrine
Inhibition of ADH
Diuresis
Inhibition of Insulin release
Hyperglycemia
Urogenital
Uterine contraction (Cows)
Alpha 2 - Anatagonists
Atipamezole (Antisedan)
"Reversal"
Yohimbine
Tolazoline
Sedation induced by Alpha 2 - Agonists may be reversed by specific Alpha 2 - Antagonists
Going to reverse Analgesic properties too!
Absorption
IM
Media attachments
Phenothiazine_Ring (image/png)
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