Neuro-Biotransformations

Question 1

What is Biotransformation

Answer 1

Enzyme driven process of converting one chemical into another

Question 2

What are xenobiotics

Answer 2

Foreign substances within the body

Question 3

What is the first pass effect

Answer 3

The process of oral drugs being absorbed in the small intestine and transported to the liver via the portal system, where they undergo metabolism.

Question 4

What is the result of the first pass system on amount of dosage of a drug that is required

Answer 4

It causes the need for more of a drug to have the same effect as something that may be administered IV

Question 5

What occurs during Phase 1 of Metabolism and what is the general result

Answer 5

Substrate is oxidized, reduced, or hydrolyzed causing the inactivation, but can become highly reactive and toxic

Question 6

What occurs during phase 2 of metabolism and what is the general result

Answer 6

Substrate is conjugated in order to increase molecular weight and water solubility for excretion

Question 7

Is phase 1 catabolic or anabolic

Answer 7

Catabolic

Question 8

Is phase 2 catabolic or anabolic

Answer 8

Anabolic

Question 9

What are the enzymes generally used during phase 1 of metabolism

Answer 9

• CYP450
• Flavin containing monooxygenases (FMO)
• Epoxide hydrolases (mEH,sEH)

Question 10

Where are the enzymes used in phase 1 of metabolism located

Answer 10

Lipophilic ER membranes of the liver

Question 11

What are the characteristics of the drug conjugated seen in phase 2 of metabolism

Answer 11

Polar molecules (water soluble) with high molecular weights

Question 12

Which phase of metabolism occurs at a faster rate

Answer 12

Phase 2

Question 13

Where does phase 2 take place

Answer 13

In the liver

Question 14

Which CYP is most commonly utilized in clearing drugs

Answer 14

CYP3A4

Question 15

Which electron transporter is most commonly used in CYPs

Answer 15

Oxygen and NADPH (one oxygen to drug and one to byproduct water)

Question 16

What is the result of a genetic defect in pseudocholinesterase

Answer 16

Pts can metabolize succinylcholine at only 50% the normal rate

Question 17

What is the result of an autosomal recessive trait resulting in a decrease in the functional N-Acetyltransferases

Answer 17

Metabolizes amines such as caffeine, hydralazine, isoniazid at a much slower rate, leading to hepatitis

Question 18

Which drugs can not be given to patients with a low level of N-Acetyltransferase

Answer 18

• caffeine
• isoniazid
• hydralazine

Question 19

What are some well documented inducers of CYP450

Answer 19

• Ethanol
• phenytoin
• benzo[a]pyrene
• rifampin
• phenobarbital
• barbiturates

Question 20

Ingestion of grape fruit juice causes what effect on which CYP

Answer 20

Irreversible binding to CYP3A4, leading to inhibition

Question 21

In a patient with gout, which drugs have to be regulated

Answer 21

Allopurinol (inhibits xanthine oxidase) can not be given with mercaptopurine

Question 22

What is the method that excessive acetopmetaphin can lead to hepatotoxicity

Answer 22

Normally, on 5% is eliminated via the glutathione. In high level of excess, more is used, depleting the stores and causing damage

Question 23

What is an example of a drug that does not follow the general order of phase metabolism

Answer 23

Isoniazid