Drug metabolism Flashcards
`what is the definition of drug metabolism?
The biochemical modification of pharmaceutical substances by living organisms, usually through enzymatic activity.
What must drugs be in order to be excreted from the body?
Water - soluble.
Why do lipid-soluble substances not get excreted?
They are passively reabsorbed back to blood due to renal function.
Where does drug metabolism take place?
Liver, gut lining, kidneys, lung.
What happens to a prodrug during metabolism?
It gets activated - rather than deactivated.
Give two examples of prodrugs.
codeine, enalapril .
What are constitutively expressed enzymes?
Enzymes that are working all the time.
what are induced enzymes?
Enzymes that work in the presence of a particular substrate.
What is phase one of metabolism?
chemical reactions - Hydrolysis, oxidation and reduction .
What is the purpose of phase one of metabolism?
to increase polarity, and to provide active sites for phase two.
What enzymes are important for phase one metabolism?
Cytochrome P450 enzymes.
What does phase two do?
Conjuction. -increases water solubility and enhances excretion.
What is drug metabolism affected by?
Other drugs, herbal remedies, age, sex, liver diesease, genetics, pregnancy etc.
what are common enzyme inducers (which in term, speed up the rate of drug metabolism, and decrease drug effects)?
Alcohol and smoking
What are some things that inhibit the enzyme activity, which can lead to the drug becoming toxic?
Grapefruit, cimenditine and erthryomycin.
