Metabolism Flashcards
(16 cards)
What is metabolism?
How the body chemically modifies a drug
What is another term for metabolism?
Biotransformation
Where does most metabolism take place?
Liver
What happens during phase one metabolism?
Functionisation
This includes oxidation, reduction and hydrolysis.
A drug is broken down into a more reactive group
What happens during phase two metabolism?
Conjugation
Results in an inactive product that is less lipid soluble, more hydrophilic and able to be renally exreted
Paracetamol is normally metabalised during what phase
One
Most phase one reactions occur due to which enzyme
CY P450
Which two cytochromes are responsible for metabolism of over 50% of drugs
CY P2D6
CY P3A4
What does an enzyme inducer do?
Turns on protein synthesis genes, therefore increasing the number of enzymes and the clearing ability of the liver
What does an enzyme inhibitor do?
Blocks enzymes and inhibits the clearance ability of the liver
Metabolism does three main things
Turns drugs into inactive products
Into toxic metabolites
into active product
What is a pro-drug
One that is inactive until metabolised
Factors affecting metabolism include
Age
Cardiac output
Hepatic function
Disease
Pharmacogenetics
First pass effect
Sex
What is enterohepatic recirculation?
Re-update of drugs or metabolitees from the small intestine which is then transported to the liver via the portal circulation
Pharmacogenetics is also known as what?
Gender Polymorphism
Why is CY P2D6 important when considering response to a medication
Absent in 5-10% of caucasions
Hyperactive in 30% of east Africans, babies and some children
