drug metabolism Flashcards
why cytochrome P450 is responsible for the generic variation in the metabolism of warfarin?
CYP2C9
where does metabolism take place
in the liver
define drug metabolism
modification through specialized enzymes
state 3 outcomesof the liver when it comes to metabolism
convert drug from toxic to non-toxic
activate prodrug
convert drug from active to inactive (helps with excretion)
what does ‘wide substrate specificity’ of metabolic enzymes mean?
the drug can be metabolised by more than one enzyme
what 2 processes are used to achieve drug metabolism
phase 1 metabolism
phase 2 metabolism
what reactions occur in phase 1 metabolism
HOR
-hydrolysis
-oxidation
-reduction
what is the role of phase 1 metabolism ?
to increase polarity of the drug and get ready for phase 2 metabolism
state 3 enzymes in phase 1 metabolism
CYP1A2
CYP2D6
CYP3A4
what is the family of enzymes that are in phase 1 metabolism
P-450
where is CYP3A4 found
in the liver
what does CYP1A2 metabolise ?
theophylline
what does CYP2D6 metabolise
antidepressants
converts codeine to morphine
how does smoking affect CYP2D6
CYP2D6 is induced by smoking
Which phase 1 enzyme isnt induced by smoking
CYP3A4
what phase involves conjugation ?
phase 2 metabolism
what is conjugation?
combing drugs to a functional group to increase its polarity
what groups are used to conjugate a drug in phase 2
glutathione
glucaronic acid
aceytl
sulphate
in what ways do herbal things affect drug metabolism and give 2 examples of herbal substances
can cause enzyme inhibition and induction
2 examples include alcohol and smoking
how long does induction take to become apparent
weeks to months
what are 2 common drugs that inhibit drug metabolism
erythromycin & clarythromycin
What two aspects of the liver can effect drug metabolism?
liver disease
hepatic blood flow
How does ethnicity effect drug metabolism?
Variation in expression of P-450 genes leading to different levels of drug metabolizing enzymes between races
