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D1 Spring > Pharmacology - Drug Metabolism and Excretion (Exam 1) > Flashcards

Pharmacology - Drug Metabolism and Excretion (Exam 1) Flashcards

1
Q

The general purpose of drug metabolism and excretion is to make the drugs more ______ soluble, so they will be excreted and not reabsorbed

A

water

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2
Q

Where does biotransformation occur?

A

many organs, but the LIVER is the most important

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3
Q

What are the 2 biotransformation reaction subdivisions?

A
  1. non-synthetic (oxidation, Phase I)
  2. synthetic (conjugation, Phase II)
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4
Q

What is a non-synthetic reaction?

A

addition of COOH, NH2, O, OH, SH

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5
Q

What is a synthetic reaction?

A

addition of group from endogenous cofactor (usually transferring something)

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6
Q

In a Phase I oxidation reaction, what is inserted into the drug or side product?

A

oxygen (usually OH group)

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7
Q

The insertion of oxygen into the drug or side product in Phase I oxidation reaction causes what to happen?

A

makes drug more hydrophilic (less lipophilic)

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8
Q

In a Phase I oxidation reaction, the reaction is catalyzed by which enzyme systems?

A
  1. cytochrome P450 system
  2. mono-oxygenase system
  3. mixed function oxidase system
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9
Q

What CYP families are responsible for most drug oxidation?

A

CYP1, CYP2, and CYP3

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9
Q

What are the components of the P450 system?

A
  1. smooth ER
  2. cytochrome P450
  3. NADPH cytochrome P450 reductase
  4. molecular oxygen
  5. NADPH
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10
Q

Put the following CYP families in order of importance:
CYP2D6, CYP2C, CYP3A

A

CYP3A (most important)
CYP2D6
CYP2C

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11
Q

Which CYPs are important for many clinical drugs?

A

CYP2C and CYP2D

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12
Q

Which CYP in the GI tract is important for the 1st pass effect?

A

CYP3A4

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13
Q

What are the 3 non-P450 oxidation reactions?

A
  1. alcohol and aldehyde oxidation
  2. purine oxidation
  3. monoamine oxidation
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14
Q

What are the other 4 metabolic reactions?

A
  1. azoreduction
  2. nitroreduction
  3. ester hydrolysis
  4. amide hydrolysis
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15
Q

What are the Phase II (conjugation/synthetic) reactions?

A
  1. glucuronidation (MOST COMMON)
  2. acetylation
  3. glutathione conjugation
  4. glycine conjugation
  5. sulfation
  6. methylation
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16
Q

What type of enzyme is used for the Phase II (conjugation/synthetic) reactions?

A

transferases

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17
Q

What are the factors affecting drug metabolism?

A

plasma protein binding, localization of drug in tissues, liver disease, and drug-drug interactions

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18
Q

Which drugs inhibit the cytochrome P450 system?

A

Cimetidine
Azole antifungals (ketoconazole)
Macrolide antibiotics (erythromycin)

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19
Q

During the induction of drug metabolism, there is an increase in ________ _________ proteins

A

cytochrome P450

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20
Q

During the induction of drug metabolism, _______ are classical and broad inducers that induce P450 to be produced

A

barbiturates

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20
Q

During the induction of drug metabolism, environmental ________ also induce more selectively

A

carcinogens

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21
Q

During the induction of drug metabolism, chronic ______ induces CYP2E1

A

alcohol

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22
Q

What are the 5 miscellaneous factors affecting drug metabolism?

A
  1. age
  2. diet
  3. disease
  4. other drugs
  5. environmental chemicals
23
Q

During the formation of toxic metabolites, _______ intermediates form and bind to cellular macromolecules

A

electrophilic

24
Q

The formation of toxic metabolites causes _________, ________, and __________.

A

necrosis, mutagenesis, and carcinogenesis

25
Q

During the formation of toxic metabolites, ___________ conjugation is the first defense

A

glutathione

26
Q

What are the principal excretion routes?

A
  1. renal (most important)
  2. biliary
  3. pulmonary
  4. miscellaneous (saliva, sweat, tears, milk)
27
Q

What are the routes of renal excretion?

A

glomerular filtration, active tubular secretion, active tubular reabsorption, passive reabsorption

28
Q

Where does glomerular filtration happen?

A

at the glomerular membranes

29
Q

What is the capacity of glomerular filtration?

A

180 L/day
20% of plasma

(high capacity)

30
Q

What are the requirements for drug filtration through the glomerulus?

A

-not too big
-not bound to plasma proteins

-lipid solubility/pH do NOT effect

31
Q

How are anions and cations involved in active tubular secretion?

A

-organic anion transporters (OATs)
-organic anion transporter peptides (OATPs)
-organic cation transporters (OCTs)

32
Q

(T/F) Active tubular secretion is saturable

A

true

33
Q

(T/F) Active tubular secretion and biliary excretion are incompletely developed in a newborn

A

true

34
Q

Is active tubular secretion specific or non-specific?

A

non-specific (causes competition)

35
Q

During active tubular secretion, inhibition by drugs such as probenecid can depress renal excretion of other ______ _______ (ex: penicillin)

A

weak acids

36
Q

What is the location and characteristics of active tubular reabsorption similar to?

A

active tubular secretion

37
Q

During active tubular reabsorption, what is it important to conserve?

A

endogenous compounds (ex: uric acid)

38
Q

What drugs inhibit active tubular reabsorption?

A

uricosuric drugs

39
Q

What does passive reabsorption require?

A

non-ionized form of drug

40
Q

(T/F) passive reabsorption involves energy

A

FALSE, there is no energy involved in passive reabsorption

41
Q

During passive reabsorption, what is the extent of drug ionization dependent upon?

A

pKa and urinary pH

42
Q

During passive reabsorption, urinary pH varies between _____ and _____, but can be manipulated with drugs to increase excretion of _______ or _______

A

5; 8; acids; bases

43
Q

Biliary excretion usually follows what?

A

Phase II conjugation in the liver

44
Q

What kind of transport processes are involved in biliary excretion?

A

multiple carrier-mediated transport

45
Q

(T/F) Biliary excretion requires energy

A

true

46
Q

(T/F) Biliary excretion is saturable

A

true

47
Q

(T/F) Biliary excretion is specific

A

FALSE, biliary excretion is non-specific

48
Q

What can occur during biliary excretion?

A

enterohepatic cycling

49
Q

What impairs biliary excretion?

A

liver disease

50
Q

What is pulmonary excretion important for?

A

gases and volatiles

51
Q

(T/F) Pulmonary excretion is simplified diffusion into expired aire

A

true

52
Q

During pulmonary excretion, the elimination rate is dependent upon what?

A

-respiration rate
-pulmonary blood flow
-solubility of the drug in blood

53
Q

_______ soluble drugs are excreted more readily

A

poorly

54
Q

(T/F) Alcohol is more soluble than nitrous oxide

A

true

alcohol is very soluble, so it is not excreted well through the pulmonary system; nitrous oxide is excreted very well through the pulmonary system

55
Q

How can you increase phenobarbital excretion?

A
  1. phenobarbital is a weak acid
  2. ionized form is excreted; non-ionized form is reabsorbed
  3. alkaline urine increases fraction of ionized form

result = increased excretion; reduced reabsorption

56
Q

How can you increase amphetamine excretion?

A
  1. amphetamine is a weak base
  2. ionized form is excreted; non-ionized form is reabsorbed
  3. acidic urine increases fraction of ionized form

result = increased excretion; reduced reabsorption

D1 Spring (47 decks)

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