Injectable Anesthetics Flashcards by Hugo Siu

What are the 4 stages in general anesthesia?

Analgesia
-> Conscious
-> Reduced pain sensation

Excitement
-> Unconscious
-> Modern anesthesia
–> Designed to shorten / eliminate this stage

Surgical anesthesia

Medullary depression
-> Deep depression of CNS

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Why are IA so hydrophobic?

Cross BBB

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Is the distribution of IA “perfusion - dependent” or “permeability - dependent”?

Perfusion - dependent

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Is anesthetic effect terminated by “metabolism” or “redistribution”?

Redistribution

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Is elimination of IA or IH generally faster?

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Provide 3 example of barbiturates with for ultra short lasting, and 1 for short lasting and long lasting effects

Ultra short
- Thiopental
- Thiamylal
- Methohexital

Short acting
- Pentobarbital

Long lasting
- Phenobarbital

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Is Thiopental, Thiamylal or Methohexital the fastest acting?

Methohexital

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What is the post synaptic receptor that Barbiturates binds to?

GABA(A)

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Which Barbiturate is used for Anticonsulvant?

Phenobarbital

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Does Barbiturates cause respiratory depression or cardiac depression?

Both

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What are 4 advantages of ultra short - acting Barbiturates?

Cheap
Rapid administration
Minimal equipment required
Rapid induction & recovery
-> After a SINGLE dose

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Why happens after repeated injections of Barbiturates?

Accumulation in fat tissue
-> Slow metabolism
–> Drug hangover
—> Prolonged recovery

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What are 4 adverse effects of Barbiturates?

Local irritation
-> Perivascular tissue necrosis
–> Barbiturate ( weak acid ) is mixed w/ NaOH
—> Sodium barbiturate = pH

Low safety margin (<2)
-> Respiratory depression
–> Can cause death
—> Used for euthanasia for lab animals though

Low doses cause excitement
-> Chances : Methohexital > Thiopental

Significant depression
-> CNS
-> Respiratory
-> Cardiovascular

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What are the two reasons we would choose Thiobarbiturate induction?

Animals w/
-> Seizure history
-> Raised intracranial pressure

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What are the two reason we would avoid using thiopental in “greyhounds”?

Deficient in oxidative enzymes
-> for drug metabolism
Recovery takes 2 - 4 times compared to other dog breeds

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What are the reason we would avoid using thiopental in “sighthounds”?

Lean breeds
-> No fat storage
–> No redistribution
–> Prolonged effect

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What should we use for greyhounds and sighthounds if thiopental is avoided?

Methohexital
-> Rapid distribution
-> Rapid metabolism
-> Quick recovery

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What is one example of pre meds used for large animals?

Guaifenesin
-> Glyceryl Guaiacolate

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What is the 2 reasons to use Guaifenesin w/ Barbiturates for large animals?

Reduce Barbiturates doses
Less side effects

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Which barbiturate should be avoided for horse and cats anesthesia w/o prior sedation?

Thiopental
-> May cause excitation

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Which barbiturate is recommended for lean dogs but not for horses?

Methohexital

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What is the 2 pharmacological effects for Guaifenesin?

Skeletal muscle relaxant
-> Central acting
Expectorant
-> Aids in removing mucus

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Is Propofol a ( barbiturate / non - barbiturate ) & ( dissociative / non - dissociative ) IA agent?

Study These Flashcards

Non - barbiturate
Non - dissociative

What is Propofol similar to? Why? ( 4 reasons )

Study These Flashcards

Thiobarbiturate
-> GABA
-> Rapid onset
-> [Cardiovascular & Respiratory depression]
-> Large doses induces apnea

What are the 7 (= =) advantages for Propofol?

Rapid hepatic & lungs metabolism -> [Used for both induction & maintenance] Suitable for outpatient procedure Recovery quality >>> Thiopental No perivascular tissue irritation -> Though small pain injection causes local pain --> Large veins recommended Maintenance of anesthesia -> When IH is not possible --> Much movement needed during the procedure Minimal effects on Babiesssss Excellent muscle relaxation

What are the 7 (= = again?) disadvantages / cautions for Propofol?

No analgesia effect Expensive Bad for cats -> Oxidative damage to RBC --> Repeated use may result in Heinz body ---> Heinz body : Deposition of denatured hemoglobin from RBC Septicemia -> If badly stored --> Ingredients favors bacterial growth Bad for horse -> May cause excitement Cardiovascular & respiratory depression -> Slow administration is recommended -> Pre med is recommended --> Reduce dosage of induction agent Overdose -> Treatment is similar to Thiopental

Other than Thiobarbiturate, what else is extremely similar to Propofol?

Etomidate ( "H"e took my date )

What is so similar about Propofol & Etomidate?

Non - barbiturate Non - dissociative Rapid onset Respiratory depression & Apnea No perivascular tissue injection Rapid hepatic metabolism No analgesic effect Expensive Induction of anesthesia - Dogs - Cats - Humans

What is the advantage of Etomidate compared to Propofol & Barbiturates?

Less cardiovascular depression

What are the disadvantages of Etomidate?

[Hemolysis & Hematuria] -> Dogs -> Cats --> Not popular in veterinary medicine [No analgesic effect] [May cause serious adrenal suppression] Pain upon injection Expensive

Is Ketamine & Tiletamine "dissociative" or "non - dissociative"?

Dissociative

Which receptors does Ketamine binds to? Is it a (competitive / non-competitive) (agonist / antagonist)?

Non - competitive antagonists -> Glutamate NMDA receptors

Does Ketamine stimulate “sympathetic” or “parasympathetic” with clinical doses?

Sympathetic -> Cardiovascular stimulation

Does large doses of Ketamine cause cardiovascular depression or stimulation?

Cardiovascular depression -> Hypotension

What are two classes of Glutamate receptors?

Metabotropic -> G protein Ionotropic -> Ligand - gated ion channel

What are two types of Glutamate Ionotropic receptors? And their functions ( Ion permeability )?

AMPA -> Na+ & K+ permeable -> Ca++ limited NMDA -> Highly Ca++ permeable --> 20 : 1 : 1 ( Ca++ : Na+ : K+ )

Does Ketamine have ‘Fast’ or ‘Slow’ elimination rate?

Slow elimination rate -> Several days

List 5 characteristic of Dissociative Anesthesia ( Cataleptic State )

Strong analgesia Unaware of the environment Eyes open Increased muscle tone -> Moves limbs -> Occasional seizure Increased salivation & lacrimation

Which hepatic enzyme is used for Ketamine metabolism?

Cytochrome P450

What is norketamine? Why do we have to be cautious about it?

Norketamine -> Metabolite of Ketamine --> 10 - 30% of Ketamine effects Cats always have impaired renal function -> Slower elimination of Norketamine --> Prolonged effect

What are 2 advantages of Dissociatives?

Less respiratory depression -> compared to Thiopental & Propofol Can be administered -> IV -> IM*** --> Used for intractable animals

Why are pre meds used with Ketamine? What are pre meds used w/ Ketamine - in Dogs - in Horses - in Large animals What are pre med used w/ Tiletamine? Choices : Guaifenesin, Diazepam, Xylazine, Detomidine, Medetomidine, Midazolam, Zolazepam

To prevent involuntary movement Dogs -> Diazepam -> Midazolam -> Medetomidine Horses -> Xylazine -> Detomidine Large animals -> Guaifenesin Tiletamine -> Zolazepam

Match the following Guaifenesin Diazepam CNS sedative (minor tranquilizer) Xylazine Detomidine Alpha2 - agonist (tranquilizer) Medetomidine Midazolam CNS sedative + muscle relaxant Zolazepam

CNS sedative (minor tranquilizer) ->Diazepam -> Midazolam -> Zolazepam Alpha2 - agonist (tranquilizer) -> Medetomidine -> Xylazine -> Detomidine CNS sedative + muscle relaxant -> Guaifenesin

Can Ketamine used in food - producing animals?

Why shouldn’t we use dissociative anesthetics as single agents for horses?

Delirium during recovery

What is the difference of Thiopental, Propofol, Etomidate & Ketamine? ( Increase, Decrease, Remains the same ) - CBF ( Cerebral blood flow ) - ICP ( Intracranial pressure ) - MAP ( Mean arterial pressure ) - HR ( Heart rate ) - CO ( Cardiac output ) - RR ( Respiratory rate ) - MV ( Minute ventilation )

CBF -> Only Ketamine increases ICP -> Only Ketamine increases MAP -> Etomidate remains the same -> Ketamine increases HR -> Propofol & Etomidate remains the same -> Ketamine increases CO -> Etomidate remains the same -> Ketamine increases RR -> Only Ketamine remains the same MV -> Only ketamine remains the same

What is the 2 Steroidal anesthetics?

Althesin Saffan

What are the difference between Althesin and Saffan?

THEY ARE EXACTLY THE SAME, IDIOT

What is the two type of steroids in Althesin / Saffan?

Alphaxalone Alphadolone

Which receptor does Althesin acts on? Is it ‘agonist’ or ‘antagonist’?

GABA(A) -> Agonists

Is Althesin short or long acting?

Short acting

What are the injection methods for Althesin?

IV IM

Is Althesin used for anesthetic induction or maintenance?

Induction - Most animals Maintenance - Cats

Why was the old formulation of steroidal anesthetics withdrawn from the market?

Severe anaphylactic reactions -> caused by vehicle : Cremophor EL --> causes Histamine release

Why is Steroidal anesthetic back on da market?

Different vehicle used -> Cyclodextran

Injectable Anesthetics Flashcards

(55 cards)