Sedatives and Analgesics Part 4 Flashcards
Name the drugs that are neuroleptic (tranquilizers)?
Acepromazine Diazepam Midazolam Alprazolam Flumazenil*
Name the drugs that are alpha 2 agonists?
Dexmedetomidine Medetomidine Xylazine Atipamezole* Yohimbine*
Name the term:
Induces a state of behavioral change wherein anxiety is relieved and the patient is relaxed although aware of their surroundings No analgesia or anesthesia when used alone
Tranquilizer (neuroleptic, anxiolytic):
Name the term:
Induces a state characterized by CNS depression and drowsiness, decreased awareness of surroundings
Sedative
Name the term:
Induces sleep
Hypnotic
Name the term:
Attenuate nociceptive input leading to reduction in pain sensation. True analgesics stop transduction and transmission of pain signals.
Analgesic
Name the term:
Decrease central sensitization to pain. They do not block the transmission of the stimulus
Antihyperalgesics
Name the term:
Diminished ability to perceive pain
Antinociception
Name the term:
Induces analgesia & stupor bordering on general anesthesia
Narcotic
Name the term:
Analgesia & amnesic state produced by administration of a neuroleptic + narcotic
Deep sedation achievable, unconsciousness may occur
Neuroleptanalgesia:
Name the term:
Drug(s) given before a medical, surgical, or invasive procedure to induce sedation, analgesia, and relieve anxiety
Pre-medication
4 steps to create a sedation and premedication plan
- Anti-convulsant
- Sedation
- Muscle Relaxation
- Analgesia
Name the 2 excitatory neurotransmitters (2)?
Glutamate (NMDA receptor)
Acetylcholine
Name the 2 inhibitory Neurotransmitters?
- GABA
- Glycine (spinal cord)
Name the Phenothiazine derivative drug?
Acepromazine
Name the Benzodiazepine derivative?
- Diazepam
- Midazolam
- Alprazolam
- Flumazenil
Name the alpha 2 agonists?
- Dexmedetomidine
- Medetomidine
- Xylazine
- Yohimbine
Main effects of the neuroleptic tranquilizers?
Sedation & hypnosis
Emotional quietness
Dissociation from surroundings
Only ____ agonists have analgesic effects? the other classes of tranquilizers do not have any pain relief properties when used alone
A2-agonists
Most common phenothiazine?
Acepromazine
Mechanism of action for Phenothiazine?
Competitively antagonize excitatory dopamine receptors in the CNS
Also variably blocks histamine, alpha-1 and Acetylcholine (muscarinic) receptors
Phenothiazines like acepromazine inhibit vomiting by?
Inhibition of alpha-2 receptors to the Chemoreceptor Trigger Zone (CRTZ) that effects Vomiting
Phenothiazine drugs increase _____ release usually that’s usually inhibited by dopamine?
Prolactin
Phenothiazines also have a minimal _____ relaxation effect?
muscle
Route of administration for phenothiazine?
Can be given IV, IM, SQ or PO
With dogs, the route of administration of Phenothiazines (Acepromazine) has this effect?
Oral bioavailability in dogs is low (~20%)
Do Phenothiazines cross the blood brain barrier?
Yes
Phenothiazines are metabolized in the?
liver and excreted in the urine
What are the Phenothiazines effects on the CNS?
- Sedation
- Decreased spontaneous motor activity
- Anti-emetic (CRTZ)
Phenothiazines effects on the cardiovascular system?
Blocks Alpha-1 receptors
-Vasodilation/hypotension
What breeds are more sensitive to cardiovascular effects of phenothiazines?
Boxers/brachycephalics, MDR1 mutants, large breed dogs and sighthounds may be more sensitive to the cardiovascular effects than other breeds so you might need to dose reduce
If Acepromazine is used in large doses with opioids, what kind if effects can we see?
Respiratory depression
Acepromazine effects on skeletal muscle?
Moderate muscle relaxation
What can be seen with the spleen with acepromazine?
Reduced hematocrit due to splenic sequestration ie. splenomegaly
When should we not use phenothiazines? Think of serious contraindications you might not want to increase?
Do not use any time vasodilation is contraindicated
Cardiac dz, hypovolemia/dehydration, epidural, etc
What are some adverse effects with stallions using acepromazine?
Penile prolapse and injury (paraphimosis)
What are the adverse effects with cattle using acepromazine?
Not approved in food animals, ruminal regurgitation can be seen
What can be seen with aggressive dogs using acepromazine?
May startle more easily, increased aggression and CNS stimulation sometimes seen.
What can be seen with excited patients using acepromazine?
reduced sedation
At larger doses or chronic doses what can be seen using acepromazine?
Functional liver disease
Main drug used in the Phenothiazine class?
Acepromazine
Sedative effects of Acepromazine?
- Yes – good, reliable sedation, but little indication for use on its own
- Combine with analgesic
Acepromazine effects on muscle relaxation?
Moderate muscle relaxation
Acepromazine analgesic effects?
none
Acepromazine this is the #1 adverse effect for cardiovascular effects?
Hypotension
Acepromazine reversal agent?
None, once given you must ride out clinical effects (2-4 hours, generally)
Name the 3 Benzodiazepine agonists?
Diazepam (Valium®)
Midazolam (Versed®)
Alprazolam (Xanax®)
Name the Benzodiazepine competitive antagonist?
Flumazenil
Benzodiazepine partial agonist?
Imepitoin
Mechanism of action for Benzodiazepine?
Bind & activate benzodiazepine binding site on GABAA receptor to cause hyperpolarization of neurons
GABA is the main….?
GABA is the main inhibitory neurotransmitter in the CNS, higher threshold and therefore less likely to fire, chloride ion channels
Benzodiazepine are ____solube so that means? And are excreted /metabolized by?
Lipid soluble (wide distribution, cross BBB, protein bound)
- Metabolized in liver to active metabolites
- Excreted in the urine primarily
Diazepams most common route of administration is? Name the adverse effects
-Most common route, give slowly IV
(avoid hypotension)
-Slow/poor absorption IM, painful injection (propylene glycol)
Midazolam most common route of administration is? Name the adverse effects
Midazolam IM (or IV): can be an irritant IM
Can think of it as the ‘version of
diazepam that you can give IM’
Describe oral administration for the benzodiazepine? Name who you can’t give orally to certain species!!
Generally good oral absorption
Diazepam has short duration, alprazolam often used instead
Note: Oral diazepam can cause hepatic necrosis in cats!!
Transmucosal (intranasal, rectal) administration for benzodiazepine?
Diazepam has decent bioavailability in dogs via these routes
Clinical uses of Benzodiazepines?
- Anxiolytics (behavioral modifiers) Ex. thunder storm anxiety /alprazolam works well for this
- Anticonvulsants: Emergency treatment of seizures and status epilepticus
- Premedication: Combined with other agents. Neuroleptanalgesia
- Sedation: (Mild) NOT reliable on its own. May have paradoxical excitation (cat on ceiling scenario). Most reliable as sedative in ruminants
Muscle relaxation: Central effects, profound, but short-lived. Urinary tract antispasmodic
Appetite stimulation: Considered more of a side effect
WHO IS USED FOR SPECIFIC REVERSAL OF BENZODIAZEPINE? Describe how it works?
Flumazenil for specific reversal
- Competitive antagonist
- Binds to benzodiazepine receptor on GABA
What do we worry about with oral diazepam to cats? What can we use instead?
Cats: Hepatotoxicity can be seen with oral diazepam! -CONTRAINDICATED
Does not seem to be a problem with oral alprazolam
What do we worry about with horses with Benzodiazepine?
Muscle fasciculations have been seen, ataxia at high doses
What do we worry about with excitatory effects with Benzodiazepine?
Paradoxical excitement sometimes seen:
- Usually combine with other agents
- Caution with fear-aggressive animals (disinhibition)
What can we seen with diazepam injections?
Propylene glycol: Pain with IM injection, hypotension with rapid IV injection, hemolysis with large IV doses
Adverse effects with pregnancy of benzodiazepine?
May be teratogenic – FDA category D for humans, category C for animals. Distributed into milk and can affect nursing neonates
Benzodiazepine can cause ____ and _____ disease?
Hepatic & Renal Disease:
Altered/delayed drug metabolism & excretion)
Benzodiazepine is Often the MOST reliable sedatives used in these categories of animals?
very young, very old, or very sick patients
True or False?
Acepromazine has tranquilizing and analgesic effects?
False (Only tranquilizing)
What is the most important cardiovascular side effect of acepromazine?
Hypotension
Why is oral diazepam contraindicated in cats?
Hepatotoxicity
What are the 3 main receptors for acepromazine?
- CNS effect ( competitive antagonism of the excitatory central dopamine = neurolepsis)
- Alpha-1 antagonism (peripheral vasodilation- hypotension)
- Alpha-2 antagonism in CNS causes vomiting inhibition
Name the main mechanism of action for Acepromazine?
competitive antagonism of the dopamine receptors in the CNS
Most common routes of administration for acepromazine?
Oral tablets most common
IV, IM, SubQ
Name the most common tranquilizer?
Acepromazine
Name the Benzodiazepines?
Dizepam, Midazalam, Alprazolam
Name the benzodiazepines receptor?
Bind and activate benzodiazepine binding site on Gaba receptor = hyperpolarization of neurons
GABA is?? what if you agonize it what does it do?
if you agonize Gaba = depress the CNS
main inhibitory transmitter for CNS