Propofol is injected intravenously where 95-99% of the drug is bound to serum albumin and hemoglobin. 1-5% of it goes to the brain and skeletal muscles to preform its mechanism of action. The rest travels to the liver where it is transported a liver transporter like OCT1 into the liver. In the endoplasmic reticulum membrane of the liver, Propofol is metabolized by Cytochrome P450 2C9 or Cytochrome P450 2B6 to make the active metabolite 4-Hydroxypropofol. 4-Hydroxypropofol has a third of the hypnotic ability of Propofol. 4-Hydroxypropofol is further metabolized by UDP-glucuronosyltransferase 1-8, UDP-glucuronosyltransferase 1-9 to make the metabolite 1-Quinol glucuronide. 4-Hydroxypropofol can also be metabolized by an unknown enzyme to make the metabolite 4-Quinol sulfate. There is also a possibility that 4-Hydroxypropofol does not metabolize into further metabolites and remains as is. Propofol also metabolizes into the metabolite Propofol glucuronide with the enzyme UDP-glucuronosyltransferase 1-8 or the enzyme UDP-glucuronosyltransferase 1-9. This further is metabolized into the metabolite 1-Quinol glucuronide with an unknown enzyme. All of these metabolites are transported back into the blood via a liver transporter such as MRP3. Here they travel to the kidney where they undergo renal excretion. 4-Hydroypropofol as an active metabolite can have similar effects on the brain as propofol.

Propofol Metabolism References