Drugs commonly used Flashcards
What are the uses of propofol?
Induction of anaesthesia
Sedation during intensive care and regional anaesthesia and can be used for…
Procedural sedation
Refractory nausea and vomiting in chemotherapy
Status epilepticus
What is propofol?
Phenol derivative; 2,6-diisopropylphenol
What is the molecular weight, pKa and acid-base status of propofol?
Molecular weight 178.27
Weak organic acid
pKa = 11
is propofol lipid soluble or insoluble?
Highly lipid soluble
How does propofol come?
Oil-in-water emulsion of 1% propofol in soybean oil, egg lecithin, benzyl alcohol to prevent microorganism inoculation, glycerol and sodium hydroxide to adjust the pH.
What is the main effect of propofol and how does it work?
Hypnotic
No-one really knows how it works but it potentiates the inhibitory transmitters glycine and GABA (to different mechanisms than thiobarbiturates and benzodiazepines) and may reduce sodium channel opening times
How is propofol given and in what dose for induction of anaesthesia?
IV and bolus of 1.5-2.5mg/kg
What rate should propofol be run at for maintenance of anaesthesia as an infusion?
4-12mg/kg/hr
How do you adjust propofol dosing for children?
Increase induction dose by 50% and maintenance infusion by 25-50%
How do you adjust propofol dosing for elderly on unstable patients?
1-1.5mg/kg induction and 3-6mg/kg/hr infusion
How does co-induction use of an opioid or benzodiazepine impact the dose of propofol required for induction?
Will reduce the dose required
Propofol will render a patient unconscious within what time after injection?
30-40 seconds
How long does it take to begin emergence from propofol as a single dose?
Approximately 10minutes
What plasma concentration of propofol will produce hypnosis or sedation respectively?
Hypnosis; 2 - 6micrograms/ml
Sedation; 0.5-1.5micrograms/ml
What effects does propofol have on the cardiovascular system?
15-25% decrease in the systemic vascular resistance and blood pressure, 20% reduction of cardiac outflow. Attenuates response to laryngoscopy in fit health patients.
How does propofol reduce SVR?
Stimulates production of NO
Propofol has a bradycardic effect which can be quite profound. How is it caused?
Possibly resets the baroreceptor reflex and may lead to asystole.
What effect does propofol have on the respiratory system as a bolus?
Can induce apnoea of variable duration (30 - >60seconds) and suppresses laryngeal reflexes.
What effect does propofol have on the respiratory system as an infusion?
Decreases tidal volume, causes tachypnoea and a decreased ventilatory response to both hypercarbia and hypoxia. Also causes bronchodilator and may preserve the mechanism of hypoxic pulmonary vasoconstriction.
What effect does propofol have on the CNS?
Smooth rapid induction and rapid clear headed emergence.
Intracranial pressure, CPP and cerebral oxygen consumption decrease.
10% of patients may develop dystonic movements due to excitatory effects. Not associated with seizure activity and can be used to treat status epilepticus. Vivid dreams, some with a sexual nature. Intraocular pressure is decreased.
