Neuro-Biotransformations Flashcards
(23 cards)
What is Biotransformation
Enzyme driven process of converting one chemical into another
What are xenobiotics
Foreign substances within the body
What is the first pass effect
The process of oral drugs being absorbed in the small intestine and transported to the liver via the portal system, where they undergo metabolism.
What is the result of the first pass system on amount of dosage of a drug that is required
It causes the need for more of a drug to have the same effect as something that may be administered IV
What occurs during Phase 1 of Metabolism and what is the general result
Substrate is oxidized, reduced, or hydrolyzed causing the inactivation, but can become highly reactive and toxic
What occurs during phase 2 of metabolism and what is the general result
Substrate is conjugated in order to increase molecular weight and water solubility for excretion
Is phase 1 catabolic or anabolic
Catabolic
Is phase 2 catabolic or anabolic
Anabolic
What are the enzymes generally used during phase 1 of metabolism
- CYP450
- Flavin containing monooxygenases (FMO)
- Epoxide hydrolases (mEH,sEH)
Where are the enzymes used in phase 1 of metabolism located
Lipophilic ER membranes of the liver
What are the characteristics of the drug conjugated seen in phase 2 of metabolism
Polar molecules (water soluble) with high molecular weights
Which phase of metabolism occurs at a faster rate
Phase 2
Where does phase 2 take place
In the liver
Which CYP is most commonly utilized in clearing drugs
CYP3A4
Which electron transporter is most commonly used in CYPs
Oxygen and NADPH (one oxygen to drug and one to byproduct water)
What is the result of a genetic defect in pseudocholinesterase
Pts can metabolize succinylcholine at only 50% the normal rate
What is the result of an autosomal recessive trait resulting in a decrease in the functional N-Acetyltransferases
Metabolizes amines such as caffeine, hydralazine, isoniazid at a much slower rate, leading to hepatitis
Which drugs can not be given to patients with a low level of N-Acetyltransferase
- caffeine
- isoniazid
- hydralazine
What are some well documented inducers of CYP450
- Ethanol
- phenytoin
- benzo[a]pyrene
- rifampin
- phenobarbital
- barbiturates
Ingestion of grape fruit juice causes what effect on which CYP
Irreversible binding to CYP3A4, leading to inhibition
In a patient with gout, which drugs have to be regulated
Allopurinol (inhibits xanthine oxidase) can not be given with mercaptopurine
What is the method that excessive acetopmetaphin can lead to hepatotoxicity
Normally, on 5% is eliminated via the glutathione. In high level of excess, more is used, depleting the stores and causing damage
What is an example of a drug that does not follow the general order of phase metabolism
Isoniazid
