Cytochrome p450 enzymes and drug metabolism 2

Question 1

Name the types of CYP450 reactions

Answer 1

aromatic hydroxylation
aliphatic hydroxylation
aliphatic dealkylation after hydroxylation
oxidative deamination
alcohol oxidation
epoxidation
heteroatom oxidation
dehalogenation
reduction

Question 2

Name the intrinsic factors affecting drug metabolism by CYPs

Answer 2

Age
Hormonal and gender differences
Genetic variability of CYP enzymes
Due to polymorphisms - can increase or decrease risk of getting a particular disease

Question 3

External factors affecting drug metabolism

Answer 3

Diet and nutritional status
Method of cooling
Alcohol and smoking
Co-administration of drugs - drug-drug interactions
exposure to drugs, solvents, xenobiotics, pollutant
diseases e.g. alcoholism

Question 4

Define drug-drug interactions

Answer 4

When 2 drugs are used together and metabolised by the same enzyme
Leads to one being metabolised more than the other

Question 5

Define perpetrator

Answer 5

Drug being metabolised

Question 6

Define victim

Answer 6

not being metabolised by the enzyme, can rise to toxic levels

Question 7

Describe the induction of enzymes (medium term)

Answer 7

Levels of enzyme increase in presence of drug
Results in tolerance - larger doses required for the same effect
Levels return to basal levels once the drug is removed
repeat exposure gives even higher levels

Question 8

Long term effects of drug metabolism

Answer 8

general reduction in drug metabolism in elderly due too age-related and anatomical changes in liver
some drugs more affected than others
extreme exposure to drugs - poisons can lead to generalised loss of metabolism
could arise due to accidental/ environmental exposure and liver disease