Propofol Flashcards
What medium is propofol presented in?
An emulsion containing 1% propofol in a lipid medium
What is the induction dose for propofol?
1 - 2.5 mg/kg (adults)
What is the onset/offset of propofol?
30 seconds on
3-7 mins off
How is propofol metabolised?
2 pathways:
- conjugated in liver to glucuronide
- hydroxylated to quinol, which is subsequently glucuronidated
What chemical class is propofol?
Phenol derivative
What physicochemical properties does propofol have?
Extremely lipid soluble
pKa 11 - exists almost completely unionized
98% bound to plasma proteins
Exists as lipid emulsion of propofol and emulsifying agent (egg phosphatide and glycerol)
Contains 1% propofol (10 mg/ml)
What physicochemical property must induction agents have in order to reach the brain?
Lipid soluble to cross the BBB
What is the MOA of propofol?
Thought to be:
- reduced opening times of sodium channels in neuronal membranes of CNS
- potentiates glycine and GABA (inhibitory neurotransmitters)
What are the RS effects of propofol?
Respiratory depression Tachypnoea and decreased tidal volume Decreased response to hypercapnea and hypoxia Bronchodilation Decreased laryngeal reflex
What are the CNS effects of propofol?
Smooth rapid induction
Decreased ICP
Decreased CPP
Myoclonic movements
What are the CVS effects of propofol?
Hypotension
Decreases SV by 15-25%
Vasodilation secondary to NO production
Bradycardia/asystole
What are the SEs of propofol?
Pain on injection
Epileptiform movements
Unlicensed in <16yrs (due to LT use in ICU - fat overload)
Green hair and urine (quinol metabolites)
Increased energy needed for DCCV
What are the chemical properties of propofol?
Poorly H2O soluble Weak organic acid pKa = 11 (almost totally un-ionised at pH 7.4) pH 7 Scavenges free radicals Physical incompatibility with atracurium
What is the metabolism and excretion of propofol?
Hepatic metabolism - mostly conjugated to inactive glucuronide
Renal excretion
Renal/liver dysfunction doesn’t alter metabolism
No active metabolites
Clearance > hepatic blood flow = extra hepatic metabolism
What are the uses of propofol?
Induction/maintenance anaesthesia
Refractory N&V
Status epilepticus
Sedation
What is the absorption/distribution of propofol?
98% protein bound
Volume of distribution = 4L/kg
Rapid distribution to tissues
Rapid elimination (T1/2 1-5hrs)
What is propofol?
2,6 diisopropylphenol
1-2% white lipid water emulsion in soya bean oil and purified egg phosphatide
