Metabolism and excretion of the drug

Question 1

What is elimination?

Answer 1

The irreversible loss of drugs from the body.

Question 2

What are the routes of elimination?

Answer 2

1- hair, tears, saliva
2. breath
3. breast milk
4. sweat
5. bile
6. urine
7. feces

Question 3

Why does a drug undergo metabolism?

Answer 3

A drug is metabolized in order to be eliminated from the body by making it more water soluble in the liver. The liver breaks things that enter the body, like food and liquids, and converts them into forms that the body can use.

Question 4

What is metabolism?

Answer 4

Metabolism consists of anabolism and catabolism that is, respectively, the build-up and breakdown of substances by enzymic conversion of one chemical entity into another within the body.

Question 5

For what is it important?

Answer 5

1. To understand the interaction between drugs and other substances
2. for developing new drugs and optimizing the dosing of existing ones

Question 6

Factors that affect drug-metabolizing enzymes:

Answer 6

1. age
2. gender
3. polymorphism
4. organ transplant
5. liver disease
6. kidney disease
7. drug-drug interaction
8. diabetes Mellitus
9. inflammatory mediators
10. pregnancy

Question 7

Explain drug metabolism briefly.

Answer 7

Lipophilic drugs undergo phase I (oxidation, reduction, and hydrolysis) if the produced metabolite is hydrophilic enough which means that it has high solubility and polarity that kidneys excrete it. On the other hand, if it is not enough hydrophilic then it undergoes phase (conjugation) to form conjugated metabolite. However, hydrophilic drugs are immediately excreted.

Question 8

What types of metabolites can be formed?

Answer 8

a. inactive - most of the drugs
b. active - administration of inactive prodrug
c. toxic - low % of paracetamol is transformed by liver enzymes into metabolite toxic to the liver

Question 9

Meaning of CYP450.

Answer 9

cyto - bound to the cell membrane
chrome - contains heme pigment
450 - wavelength