Pharm 2.1: Elimination

Question 1

What is the difference between substance mother and metabolite

Answer 1

There are times where a medication is active and it’s taken form we say that this is a mother substance that is active

In other cases the mother substance is not active but it is the metabolite that is active
And these are called pro drugs when the mother substance is not active

Question 2

Hypophilic vs hydrophilic medication and their relationship to elimination
Difference

Answer 2

Most medication is hypophilic and this cannot be eliminated by the kidneys
So the job of the liver is to conjugate and make these medications hydrophilic

Question 3

What is the main molecule responsible for phase one medication metabolism

Answer 3

Cytochrome P450

Question 4

Describe how the cytochrome P450 reduction works

Answer 4

It uses the reduction of iron(Fe3+ to Fe2+) to attach an OH group to the substance in this case the medication in order to make it hydrophilic

Iron heme is important

Question 5

What are the cytochrome P450 isoforms that we have to remember

Answer 5

• CYP3A4/3A5
• CYP2D6
• CYP2C9
• CYP2C19

Question 6

True or false
In certain cases the metabolite of the mother substance will not be active but rather toxic a
As such a decrease in CYP2E1 activity could lead to Intoxications to patients taking acetaminophen

Answer 6

False
It is true that certain metabolites are toxic and in the example of acetaminophen it is the case
However it is the increase activity in the cytochrome 2E1 that causes the toxicity

Question 7

What is special about the CYP3A4/3A5 polymorphism?

Answer 7

Both is 3A4 and the 3A5 do the same thing
However for patients that might have one of them deactivated it might make them slower metabolisers and so the drug dose must be change accordingly

Question 8

What is special about the CYP2D6 polymorphism?

Answer 8

Some patients are ultra rapid metabolites others are very slow metabolizers
This means that for the same medication you will have a different amount of active metabolites or clearance depending on the drug

Question 9

What are the three modulations of cytochrome 450 that we can do

Answer 9

Genetic due to a polymorphism which can lead to increased activity or decreased activity
Inhibition which can be either reversible or non reversible
Induction