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Meharry PHARM > Drug Metabolism / Drug Biotransformation > Flashcards

Drug Metabolism / Drug Biotransformation Flashcards

1
Q

____ = drug geting into bloodstream

A

absorption

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2
Q

___ = gets to site of action

A

distribution

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3
Q

_ = “changed” so that it can

be excreted

A

Metabolism

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4
Q

____ = leaves the body

A

Elimination leaves the body

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5
Q

another word for metabolism is

A

biotransformation

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6
Q

what is this : complex of processes which provide
decreasing of toxicity and accelerate
excreting of the molecule of a drug or other foreign substance after its incoming
into the organism

A

biotransformation / metabolism

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7
Q

what is the aim of metabolism of drugs

A

to convert non-polar lipid soluble
compounds to polar lipid insoluble compounds
to avoid reabsorption in renal tubules

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8
Q

are hydrophillic drugs more or less transformed

A

Most hydrophilic drugs are less biotransformed
and excreted unchanged – streptomycin,
neostigmine and pancuronium etc.

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9
Q

what protects the

body from toxic metabolites?

A

Biotransformation is required for protection of

body from toxic metabolites

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10
Q

The process of alterations in the drug structure by the enzymes in the body is called ______ .

A

The process of alterations in the drug structure by the

enzymes in the body is called “biotransformation (drug metabolism)”

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11
Q

The products form after biotransformation

are called _____

A

products form after these reactions

are called “drug metabolites”.

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12
Q

a drug didnt have any activity in vitro, but gains

activity after it undergoes biotransformation in the body this is an example of

A

“pro-drug” or

“inactive precursor”.

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13
Q

what are the 4 possible out comes of biotransformation

A
  1. Active drug and its metabolite to inactive metabolites
  2. Active drug to active product
  3. Inactive drug to active/enhanced activity
  4. No toxic or less toxic drug to toxic metabolites
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14
Q

what are the 4 enzymatic reactions which the drugs are exposed to:

A
  1. Oxidation
  2. Reduction
  3. Hydrolysis
  4. Conjugation
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15
Q

what are 3 possible outcomes of phase 1 of enzymatic reactions

A

oxidation
reduction
hydrolysis

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16
Q

what happens during phase II of enzymatic reactions

A

conjugation

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17
Q

What is the main function of Phase I metabolism?

A

The Main function of Phase I metabolism is to

prepare the compound for phase II metabolism

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18
Q

Describe in detail what happens in phase 1 of metabolism

A

Converts the parent drug to a more polar
metabolite by introducing or unmasking a
functional group (-OH, -NH2
, -SH)

19
Q

T/F phase 1 metabolism typically results in loss of pharmalogical activity

A

true

20
Q

Oxidation reactions are performed mostly*** by the enzymes in
______which are localized in the ____in microsomal fractions.

A

Oxidation reactions are performed mostly*** by the enzymes in
liver (hepatocytes) which are localized in the endoplasmic
reticulum in microsomal fractions.

21
Q

what kind of enzymes are used in oxidation reactions

A

cytochrome P450 mixed-functional

oxidases.

22
Q

what 3 things are required for oxidation reactions

A
  1. cytochrome P450
  2. molecular oxygen (O2)
  3. NADPH
23
Q

What 2 things are required for opitical acitivty of p450

A

NADPH and molecular oxygen (O2) is required for its activity.

24
Q

Cytochrome P450 is a “___” containing protein

A

Cytochrome P450 is a “heme” containing protein

25
Q

What is the active site of the cytochrome p450 protein

A

Fe ion

26
Q

what state does Fe have to be in for cytochrome p450 to bind

A

Fe3+

27
Q

what is the name of the enzyme that that releases electrons from NADPH

A

After the formation of enzyme-drug complex, an
electron (e-
) released from NADPH by the enzyme
NADPH-cytochrome P450 reductase is transferred to
this complex.

28
Q

P450 1, 2 and 3 (CYP1, CYP2 and CYP3) genes are
involved in coding the enzymes which are responsible
for the drug metabolism. Which one codes the enzymes that are
responsible for the pre-systemic elimination of orally
administered drugs.

A

CYP3

29
Q

are oxidation or reduction reactions more likely to occur

A

oxidation

30
Q

what is required for reduction, that is not needed for oxidation

A

FAD is required additional to NADPH for these

reactions.

31
Q

Does true detoxification of drugs typically occur in phase 1 or phase 2

A

Phase II is usually the true detoxification of drugs

32
Q

what part of the cell does phase 2 occur

A

 Occurs mostly in cytosol

33
Q

Glucuronidation is an example of what kind of reaction

A

conjugation

34
Q

what is the name of the enzyme for conguation reactions

A

UDP-glucuronosyltransferases catalyze the reaction.

This is a microsomal enzyme located in the endoplasmic
reticulum of liver cell.

35
Q

why is taking high dose dangerous

A

Acetaminophen is 95% metabolized by
gulcuronidation and sulfation

Partially (4%) converted to quinoneimine (potent
liver toxicant), by P450

At high doses, sulfation and gulcuronidation
pathways get saturated, increasing the P450 ratio

36
Q

List 6 factors affecting Factors That Affect The Biotransformation of Drugs

A
  1. Induction or inhibition of microsomal
    enzymes
  2. Genetic differences
  3. Age
  4. Gender
  5. Liver diseases
  6. Environmental factors
37
Q

What is biochemical tolerance

A

some drugs stimulate the enzymes

that inhibit themselves

38
Q

the CYP2D6 polymorphism is also known as

A

“debrisoquine type

polymorphism”.

39
Q

T/F In newborns cytochrome P450 enzymes and

glucuronosyltransferases are not sufficient.

A

true

40
Q

is bio transformation fast or slow in newborns

A

slow

41
Q

does first pass elimination increase or decrease with age

A

reduces

42
Q

describe how metabolism changes with gender

A

Metabolism rates of some drugs may change with gender. For
example, succinylcholine and other choline esters and procaine
are inactivated faster in men.

43
Q

how does liver disease affect clearance

A

Especially, the metabolism of drugs with a “high

hepatic clearance” decreases in liver diseases.

44
Q

what fruit can inhibit enzymes

A

grapefruit

Meharry PHARM (24 decks)

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