It is rapidly distributed in the body with a propofol half life of only around 2 mm and has an efficient hepatic and extrahepatic clearance.
Because the total body clearance may exceed liver blood flow, an extrahepatic metabolism or extrarenal elimination has been suggested.
Hepatic metabolism is rapid and extensive, resulting in inactive, water-soluble sulfate and glucuronic acid metabolites that are excreted by the kidneys.
Propofol half life is metabolized by oxidation to I,4-di-iopropylquinol. Both propofol itself and its metabolite 1,4-di-isopropylquinol are in turn conjugated with glucuronic acid to the respective glucuronides, propofol glucuronide, quinol-1-glucuronide and quinol-4-glucuronide.
Propofol may also undergo ring hydroxylation by cytochrome P450 to form 4-hydroxypropofol which is then glucuronidated or sulfated.
Although the glucuronide and sulfate conjugates of propofol appear to be pharmacologically inactive, 4-hydroxypropofol possesses some hypnotic activity of propofol half life .
Dawidowicz et al documented in their study that propofol is not excreted by kidneys in unchanged form.
The elimination propofol half life is 0.5 to 1.5 hours. But the context sensitive half-time (the time required for the plasma drug concentration to decline by 50% after terminating each infusion is called as “context-sensitive half-time,” where “context” refers to infusion duration) for propofol infusions lasting up to 8 hours is <40 minutes.