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All of the following are true concerning propofol EXCEPT:


A. The short duration of action after a single IV bolus dose are due to a redistribution phenomenon

B.  Propofol decreases cerebral blood flow (CBF)

C. Propofol's  mechanism of action is through the GABA type A receptor

D. Propofol has moderate analgesic properties

E.  Propofol follows a context-sensitive half life
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==Answer==
The correct answer is D. All the other statements are true.  It has NO analgesic properties. Propofol is highly protein bound <i>in vivo</i> and is metabolized by conjugation in the liver. Its rate of clearance exceeds hepatic blood flow, suggesting an extra-hepatic site (plasma) elimination as well. It has several mechanisms of action, both through potentiation of GABA-A receptor activity, thereby slowing the channel closing time, and also acting as a sodium channel blocker. Recent research has also suggested the endo-cannabinoid system may contribute significantly to propofol's anesthetic action and to its unique properties.

The elimination half-life of propofol has been estimated to be between 2-24 hours. However, its duration of clinical effect is much shorter because propofol is rapidly distributed into peripheral tissues (redistribution). When used for IV sedation, propofol typically wears off in minutes after a single bolus.  When used as an infusion, redistribution becomes less important because the non-target tissues have become saturated as well. After infusion, the half life of propofol is mostly due to its plasma/liver metabolism and therefore its effects are extended. In practice, if you infuse propofol for about 6 hours, expect the effects to last about 30-40 minutes instead of the 8-10 minutes you are used to after a single bolus. Its use is not associated with nausea as is often seen with opioid medications and may actually be used as an anti-emetic in sub-anesthetic doses. <ref>Langley MS1, Heel RC. Propofol. A review of its pharmacodynamic and pharmacokinetic properties and use as an intravenous anaesthetic. Drugs. 1988 Apr;35(4):334-72. [http://www.ncbi.nlm.nih.gov/pubmed/3292208]</ref>
==Notes==
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==Keywords==
:[[Wikipedia:Propofol]]
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