Zusammenfassung der Ressource
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