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Pharm Test 1 > 09/04 Class 4 > Flashcards

09/04 Class 4 Flashcards

1
Q

Elimination is dependent on

A

which organ is eliminating the drug

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2
Q

The organ that is eliminating a drug is dependent on

A
  1. Whether or not the drug is a high-extraction drug
  2. what the blood flow is through that organ
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3
Q

If the blood flow through an elimination organ is normal, we call it

A

high

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4
Q

If the blood flow through an elimination organ is limited, we call it

A

low

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5
Q

Oral morphine doesn’t provide the full effect because

A

After the GI tract morphine goes into the liver and the liver removes a lot of it. It is a high extraction drug

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6
Q

What is the range for a high extraction drug?

A

> 0.7

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7
Q

What is the range for an intermediate extraction drug?

A

0.3-0.7

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8
Q

What is the range for a low extraction drug?

A

<0.3

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9
Q

What is Q in the extraction ratio?

A

The blood flow through an elimination organ.

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10
Q

What is the Clorgan formula?

A

Clorgan=QE

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11
Q

What is E in the extraction ratio?

A

the percentage of drug that comes out of an elimination organ

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12
Q

If you have a high E and a low Q, what is your Clorgan?

A

Low

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13
Q

If you have a low E and a high Q, what is your Clorgan?

A

Low

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14
Q

If you have a high E and a high Q, what is your Clorgan?

A

high

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15
Q

If you have a low E and a low Q, what is your Clorgan?

A

low

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16
Q

Why is the half life important?

A

It helps us determine how we should dose a patient and how much we should dose them

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17
Q

Define half life

A

the time it takes the body to get rid of half of the concentration of a drug in the blood

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18
Q

What is the half life formula?

A

T1/2=0.7XVd/CL

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19
Q

What is giving a drug in “steady state” mean?

A

Giving the drug at the same rate that the body is eliminating it.

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20
Q

What do we do to reach target concentration quickly?

A

Give a bolus of a drug

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21
Q

For a drug that has a 4 hour half life, how many half lives would it take for the drug given at steady state to reach target concentration in the blood?

A

16 hours

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22
Q

For a drug that has a 4 hour half life, how many half lives would it take for the drug to be completely eliminated from the blood after the infusion is stopped?

A

16 hours

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23
Q

What effects half life?

A

Many things, including disease state

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24
Q

A true half life will be _____ than the calculated half life

A

greater

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25
Q

If you don’t wait 4 half lives before taking another dose of the drug, what will happen?

A

The drug will accumulate in the plasma and can become toxic very quickly

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26
Q

How is bioavailability denoted?

A

F

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27
Q

What does bioavailability tell us?

A

How much of the drug reaches systemic circulation

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28
Q

What is the bioavailability of an IV drug?

A

100%

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29
Q

What factors effect bioavailability?

A
  • Physical properties of the drug (hydrophylicity, PKA, solubility)
  • Fomulation/route
  • GI- diet, gastric emptying, transporters, health
  • interactions with other drugs
  • disease state
  • circadian rhythm
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30
Q

What is first pass elimination?

A

The first system that the drug goes through that changes the concentration of the drug.

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31
Q

What are routes that bypass first pass elimination?

A
  • IV
  • IM
  • SC
  • Inhalation
    *has it’s own first past effect
  • sublingual
  • transdermal
  • rectal
    *suppositories might move upward, therefore only 50% bypass hepatic circulation
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32
Q

What is target concentration based on?

A

What we are trying to accomplish in the patient (pain relief, controlling afib)

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33
Q

What is the most important factor of the dosing ratess?

A

Clearance

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34
Q

How do you solve for dosing ratess?

A

CL X Target concentration

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35
Q

For bioavailability that is less than 100%, how is the formula changed?

A

Dosing rateoral=dosing rate (calc.)/Foral

The CL X Target concentration is divided by the bioavailability.

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36
Q

If your bioavailability is less, your are going to have to give _____ of the drug

A

more

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37
Q

What is an intermittent dose for oral drugs?

A

Giving a pill every few hours instead of constantly.

Dosing rate X dosing interval (in hours)

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38
Q

If you are given the target concentration, the clearance, and the time interval how do you solve for the intermittent dose?

A
  1. Dosing ratess=CL X Target Concentration
  2. Dosing rateoral=dosing cate (calc.)/ForalX dosing interval
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39
Q

Describe what is happening in this graph.

A

The black line is the drug being given in steady state. It is showing that after 4 half lives, the drug reaches 10mg/L and the patient is receiving the targeted effect of the drug.
The red line shows the drug being given every 8 hours. The patient has peaks and troughs that’s staying right around the target concentration.
The blue line is the drug being given every 24 hours. You can see that at the peaks the patient is receiving a much higher effect than the target concentration, but the troughs are also much lower. In the case of this siezure drug, you can see how the troughs would leave this patient open to having seizures.

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40
Q

How to calculate the loading dose?

A

LD=Vd X TC

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41
Q

The loading dose is assumed that it is given over

A

5 minutes

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42
Q

Why is rate of administrations critical for potentially toxic drugs?

A

Giving a bolus too fast doesn’t allow time for the drug to distribute into compartments and therefore reaches toxic levels in the plasma very quickly

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43
Q

How do we monitor for therapeutic dosing?

A

Peak and trough tests

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44
Q

When is the peak test taken?

A

5-10 minutes after drug administration

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45
Q

When is the trough test taken?

A

30 minutes before the next dose

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46
Q

What do the peak and trough tests tell us?

A

Assessment of individual response to standard population pharmacokinetic variables.
To be able to dose the drug to each individual patient based on their disease state, other drugs they’re on etc.

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47
Q

If you have a drug that preferentially stays in the fat, which weight do you use?

A

their actual weight

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48
Q

If you have a drug that preferentially stays in the blood stream, which weight do you use?

A

Their Ideal body weight

49
Q

What test tells us how well the kidneys are functioning, and how does it work?

A

The creatinine clearance.
The muscles release a steady rate of creatine in the blood as waste which gets down to the kidneys for excretion. If creatinine starts to build up in the body then it is safe to assume that the kidneys are not functioning properly.

50
Q

What is biotransformation?

A

The changing of a drug to either make it work better, or in most cases to decrease or stop the drug from working altogether.

51
Q

What is the second largest organ in the body?

A

the liver, after the skin

52
Q

Where does most, but not all, biotransformation happen?

A

The liver

53
Q

What is in the hepatic portal system?

A
  1. oral
  2. gi
  3. local veins
  4. hepatic portal vein
  5. sinusoids very leaky
  6. hepatocytes
  7. hepatic vein
  8. vena cava
  9. systemic circulation
54
Q

Where is a drug biotransformed?

A

Hepatocytes

55
Q

What are the 2 different places that biotransformed drugs can go after the hepatocytes?

A

Back into the blood stream to be delivered to the body
Into the Bile duct to be eliminated through bile

56
Q

What is the circulation for a drug given in a central line?

A
  1. Vena cava
  2. r atrium
  3. r ventricle
  4. l atrium
  5. l ventricle
  6. systemic cirulation
  7. hepatic artery
  8. sinusoids
  9. hepatic vein
  10. vena cava
  11. systemic circulation
57
Q

Why are the sinusoids an area with fairly low oxygen concentration?

A

Because blood from the hepatic portal vein and the hepatic artery both mix here

58
Q

What are the sinusoids in the liver very susceptible to?

A

Heart failure

59
Q

Do sinusoids regenerate quickly?

A

yes

60
Q

What are phase 1 reactions?

A

When we take an enzyme and either add or unmask a functional group (-OH, -NH, -SH et.) very small substances.

61
Q

What are phase 2 reactions?

A

We’re tacking on larger molecules

62
Q

In some way, phase 1 and phase 2 help with the ______ of a drug.

A

elimination

63
Q

Is there a specific order phase 1 and phase 2 has to happen?

A

No, and they don’t have to go through both reactions.

64
Q

Phase 1 turns the drug into a more _______ metabolite. Making it harder to cross into the cell and therefore easier to eliminate.

A

polar

65
Q

Phase 2 reactions are ________ reactions.

A

conjugate
meaning to combine 2 things

66
Q

Phase 1=

A

oxidation, reduction, hydrolysis

67
Q

After phase 1 most drugs are

A

inactivated

68
Q

Phase 2 results in drugs with a ________

A

higher molecular weight, essentially detoxifying the drug by making it harder to cross into the cell.

69
Q

What are the 4 main groups of phase 1?

A

Oxidation
reduction
dehydrogenation
hydrolysis

70
Q

What is oxidation?

A

Loss of an electron

71
Q

What is reduction?

A

Gaining of an electron

72
Q

What is dehydrogenation?

A

removing an OH group

73
Q

What is hydrolysis?

A

breaking down of water in a reaction and that breaks a bond

74
Q

Why are we focusing on oxidation reactions?

A

Because that is how vast majority of drugs are modified in phase 1 reactions.

75
Q

What is used in the primary oxidation pathway?

A

an enzyme called Cytochrome P450. It’s a molecule

76
Q

P450 cycle

A
  1. drug comes in lipophilic
  2. binds to CYP450
  3. loss of E-
    * Flavoprotein oxidizes and becomes oxidized
    * then goes through the compound NADPH
    * NADPH is reduced turning into NADP+
    * NADPH is recycled somewhere in the liver
    * Now Favoprotein is recycled and is in it’s reduced form
  4. P450 molecule is a holder for the drug
  5. 2 Oxygen molecules and electrons are added to the drug
  6. Oxygen detaches from the drug and attaches to 2 Hydrogen turning into water
  7. The other oxygen stays on the drug and becomes a hydroxyl group
  8. Drug is then more hydrophilic & is released into either the circulation to be excreted by the kidneys or the bile to be excreted through the intestines
77
Q

What takes electrons from P450?

A

Flavoprotein

78
Q

What is the most common flavoprotein?

A

Flavin mononucleotide
FMN

79
Q

By oxidizing P450, Flavoproteins become

A

oxidized themselves

80
Q

CYP3A4 synthesize what percent of oxidation reduction reactions?

A

50%

81
Q

CYP2D6 synthesize what percent of oxidation reduction reactions?

A

20%

82
Q

CYP2B6 synthesize what percent of oxidation reduction reactions?

A

8%

83
Q

What does CYP short for?

A

Cytochrome P450

84
Q

What is the most important CYP450?

A

CYP3A4

85
Q

Where does the oxidation reaction happen inside of the hepatocyte?

A

Sarcoplasmic reticulum

86
Q

CYP384*1 means

A

this is a wild type

87
Q

what does the wild type mean?

A

it is the variant that is most commonly seen in the population.

88
Q

CYP3A4*2

A

is a mutant of the CYP3A4*1 and may have different activity.

89
Q

What is a polymorphic variant?

A

A deviation from the wild type that may have a greater, lesser, or same effect as the wild type.

90
Q

What produces variants?

A

Genetic mutations

91
Q

What is a P450 induction?

A

a drug(medicine, food, charbroiled) that increases the number of cytochrome P450 enzymes which increases the CYP3A4 enzyme which effects the drug

92
Q

What is a P450 Inhibition?

A

A drug(medicine, food, charbroiled) that decreases the number of cytochrome P450 enzymes which decreases the CYP3A4 enzyme which effects the drug

93
Q

If a drug is inactivated by CYP3A4, and we take an inducer, what will happen?

A

The drug will become inactivated at a much faster rate.

Less drug effect

94
Q

What is a prodrug?

A

something that has to be activated by CYP3A4

95
Q

If a drug is activated by CYP3A4, and we take an inducer, what will happen?

A

The drug will be become active much more quickly and may reach toxic effects quickly.

more drug effect

96
Q

If a drug is inactivated by CYP3A4, and we take an inhibitor, what will happen?

A

Less of the drug is being inactivated, meaning more of the drug is being released into the body and you may reach toxic effects faster.

more drug effect

97
Q

If a drug is activated by CYP3A4, and we take an inhibitor, what will happen?

A

Less of the drug will become activated, meaning that less of the active drug will be available in the plasma.

Less drug effect

98
Q

What is glucuronidation?

A

attaching a glucose

99
Q

What is the acetylation?

A

attaching an Acetyl-CoA

100
Q

What is Glutathione conjugation?

A

attaching a glutathione (GSH)

101
Q

What is Glycine conjugation?

A

attaching a Glycine

102
Q

What is sulfation?

A

attaching a Phosphoadenosyl phosphosulfate

103
Q

What is Methylation

A

attaching a S-Adenosylmethionine

104
Q

What is water conjugation?

A

attaching a water

105
Q

What is a UGT?

A

Uridine diphosphate glucuronyltransferases
a type of glucuronidation reaction
They attach a glucuronic acid to molecules
A carrier molecule with the Glucuron transferase (which transfers a glucose molecule from UDP to the drug itself)

106
Q

What do UGT’s attach a glucuronic acid to?

A

Phenols, alcohols, carboxyl, and sufhydryl groups

107
Q

Where are UGT’s primarily found?

A

in the liver

108
Q

What is uridine diphosphate?

A

the carrier molecule

109
Q

What do the glucuronyltranferases do?

A

Transfers a glucose molecule from UDP to the drug itself

110
Q

What is the response of a drug undergoing glucuronidation?

A

It becomes more aqueous soluble, and is excreted via the urine more easily

111
Q

What is a Glutathione-S-transferase? GST

A

attach a glutathione

112
Q

Glutathione characteristics

A

ubiquitous
Critically important in detoxification
Increases water solubility to get rid of toxins

113
Q

Where are glutathiones found?

A

Everywhere. Really high in RBC’s because they can build up high amounts of oxidants in them because they carry oxygen.

114
Q

What is a xenobiotic?

A

something that is foreign in the body

115
Q

What happens to xenobiotics when a glutathione binds to it?

A

It forms a glutathione conjugate which makes it more likely to be excreted in the urine

116
Q

What does overdosing do?

A

It overwhelms the normal detox pathways

117
Q

What are extrahepatic metabolism examples?

A

Brain
Lung
Intestine
Plasma
Kidney

118
Q

What are things that change the way we metabolize drugs?

A

diet
environment
age and sex
disease state
genetics

DEAD Genetics

Pharm Test 1 (5 decks)

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