2- Drugs for induction Flashcards
Give 3 routes induction drugs can be delivered
IM, IV, Sub cut, Inhalation, Skin, Dart gun
Name 4 characteristics of an ideal induction drug
Minimal cardiovascular & respiratory depression
Rapid metabolism
Causes hypnosis & amnesia
Rapid onset
No hypersensitivity reaction
Non-irritant
small volumes needed for induction
Inexpensive
Stable formulation
Name 2 induction drugs
Propofol
Alfaxalone
Ketamine
Volatile agents
T/F propofol is 98% protein bound
True
How is propofol excreted?
Renally
Where is propofol metabolised
Liver- glucuronidation
Mechanism of propofol
Enhances GABA (inhibitory function)
Binds to GABAA Beta subunit
Increases duration that the cl- channel is open
What effects does propofol have?
Respiratory depression
Decreased cerebral metabolic rate of oxygen (CMRO2)
Depresses cardiovascular reflexes
This causes = Decreased heart rate, mean arterial pressure (MAP), systemic vascular resistance & central venous pressure
List some propofol side effects
Apnoea common
Twitching, myoclonus can occur- usually passes within 10-15mins
What is the mechanism of alfaxalone?
Causes anaesthesia by activating the GABA (inhibitory) receptor
What effect does alfaxalone on Cerebral metabolic rate of oxygen (CMRO2)?
Decreases
T/F Alfaxalone has minimal effects on HR, Cardiac output & MAP
True
T/F Apnoea is more common with alfaxalone than propofol
False- very common in propofol
Where is alfaxalone metabolised
Liver, rapid
also lungs and kidney
Where is alfaxalone eliminated
renal, and small % in bile
Is ketamine water or lipid soluble?
water soluble
What receptor does ketamine work at?
NMDA receptor antagonist
What induction agent is the only one that provides analgesia?
Ketamine
What controlled drug schedule is ketamine under? & what does this mean for storage?
Schedule 2 = locked in cupboard
Name the 2 volatile agents
Isoflurane & Sevoflurane
Where is ketamine metabolised
liver to norketamine
where is ketamine eliminated
renal and small % in the bile
Volatile agents are absorbed via…. and excreted via….
lungs and lungs
What is the side effect of volatile agents?
Cardiopulmonary depression
- reduced cardiac output
- Reduced HR
- Decreased MAP, SVR, CVP
what is the speed of induction of Intravenous induction drugs proportional to
speed of induction is proportional to the cardiac output
what is the speed of induction via mask or chamber proportional to
speed of induction is inversely proportional to the cardiac output due to the negative effects of the cardiac output on the alveolar partial pressure.
Describe how to use propofol
titrate to effect
give slowely IV over 60secs
Apnoea common
Which species is propofol licensed in?
Dogs and cats
