Pharmacology of Injectable Drugs Flashcards
What are the advantages of injectable anaesthesia?
- Little equipment needed (syringes, needles, IV catheters)
- Usually, easy to administer
- Induction of anaesthesia can be rapid & smooth
- Possibly relatively cheap
- Limited environmental pollution (inhalants –> Greenhouse effect; plastics)
What are the disadvantages of injectable anaesthesia?
- Once given, retrieval is impossible
- The P must be weighed accurately to calculate the dose, esp in the smaller animals!
- Dose readjustment in sick/debilitated animals
- Some drugs have the potential for human abuse
- Risks of inadvertent self-administration
All drugs have the potential to cause…
apnoea, so be prepared for immediate intubation
propofol is what type of injectable anaesthetic?
non-barbiturate
What is the MoA of Propofol?
- GABA(alpha) receptor (beta subunit) –> slows down closure, activates directly
- indirectly potentiates activation of the channels
- direct in high amounts, will directly activate GABA
Propofol solubility
Insoluble in water
highly lipid solube
Propofol formulation contains…
10% soybean oil
2.25% glycerol
3.1.2% purified egg phosphatide
Great media for bacterial growth
If no preservatives are present in Propofol, how long is the vial good for?
24 hrs
Propoflo 28/PropoVet multidose uses what as a preservative?
benzyl alcohol, which can accumulate & be toxic
Do not use for TIVA
What is the propofol onset of action?
60-90 sec or faster
What is the duration of action of Propofol?
About 10-15 min of anaesthesia
Propofol is suitable for…
inductions & maintenance as CRI (preservative-free only)
Protein binding of propofol?
- Free fraction in plasma only 1.2-1.7%
- Binds to albumin/erythrocytes
- Low RBCs impacts dosage
- Free fraction in CSF 31%
Elimination of Propofol?
Exceeds hepatic blood flow
Extra-hepatic metabolisation sites –> kidneys, SI, lungs?
Metabolite: glucuronidation into non-active metabolites
Propofol has dose-dependent CV depression which causes what signs?
- vasodilation
- negative inotropic
- reduction of CO
- compensatory increase in HR abolished
Dose & rate dependent respiratory depression caused by Propofol causes what signs?
hypoventilation
apnoea
Propofol does not have
analgesic properties
What are the neuroprotective effects of Propofol?
Decreases ICP, cerebral metabolic rate (CMRO2), & cerebral perfusion pressure in P’s w/ high ICP
What is unique about propofol usage in cats?
- prolonged recoveries after repetitive boluses or long infusions
- feline hgb prone to oxidative injury by phenolic compounds which decrease PCV –> Heinz body anaemia if given several boluses over multiple days
- TIVA - difficult recovery
- Repeated or prolonged propofol anaesthesia leads to: anorexia, depression, D, facial oedema, delayed recovery
What patients indicate the use of propofol?
- C-sections
- Renal p’s
- Hepatic p’s
- TIVA
What are the patient contraindications of Propofol?
- hypovolaemia/shock
- heart failure
- diabetic hyperlipidaemia/pancreatitis?
- avoid repeated propofol/>30 min TIVA in cats
What are the main uses of Propofol?
- Sedation in SA
- induction of anaesthesia
- balanced anaesthesia
- maintenance (TIVA/PIVA)
Alfaxalone is what kind of anesthetic?
steroid
Alfaxalone is licensed in what species?
dogs, cats, rabbits, other wildlife