Detoxification

Question 1

What are xenobiotics?

Answer 1

foreign substances that can be absorbed but not metabolised (energy producing)

Question 2

What are some examples of xenobiotics?

Answer 2

drugs

Question 3

How are xenobiotics absorbed and excreted?

Answer 3

across lungs, skin or ingested

excreted in bile, urine, sweat and breath

Question 4

xenobiotics are what kind of substances?

Answer 4

lipophilic substances

lipid soluble

Question 5

What needs to happen to them so they can be excreted?

Answer 5

need to be modified by liver to be less lipophilic

Question 6

What reactions do the xenobiotics need to undergo?

Answer 6

phase 1 reaction - biotranformation

phase 2 reaction - conjugation

Question 7

Phase 1 reaction
Process?
adds what?
enzyme?

Answer 7

oxidation (hydrolysis and reduction also occurs)

adds an OH hydroxyl group to the drug, increases hydrophilic as OH can interact with water

Microsomal enzyme (on smooth ER)
CYP450

Question 8

Phase 2 reaction
Process?
adds what?
enzyme?

Answer 8

glucuronidation

adding glucuronic acid (glucuronide) to make it even more hydrophilic

non microsomal enzymes (in mitochondria & cytoplasm of hepatocytes)
UGT (coenzyme UDGPA)

Question 9

Alcohol detoxification
alcohol —> ?
enzyme

Answer 9

alcohol —> Acetaldehyde

ADH - alcohol dehydrogenase

Question 10

Alcohol detoxification
Acetaldehyde —>?
enzyme

Answer 10

Acetaldehyde —> Acetate

ALDH-aldehyde dehydrogenase

Question 11

Alcohol detoxification
Acetate —>?
What can the products cause?

Answer 11

Acetate —> CO2 + H20

can cause acidosis (CO2 is an acidic gas)

Question 12

What is acetaldehyde?

what can it cause

Answer 12

It is carcinogenic

facial flushing, rapid heart beat and nausea