Week 3- Pharmacokinetics Flashcards

1
Q

Which test is most specific in regards to renal functioning and drug clearance?

A

Creatinine clearance; uses age, serum creatinine and predicted creatinine production rate

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2
Q

Where is it easier for acidic drugs to be absorbed?

A

Stomach; low pH; stays in non-ionized form here

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3
Q

Describe what happens in a conjugation metabolic reaction (Phase 2 RXN)Describe what happens in a conjugation metabolic reaction (Phase 2 RXN)

A

Glucuronic acid compound added to drugs to make them more polar
more polar = more hydrophilic = easier to excrete

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4
Q

What is the main benefit of a time release capsule?

A

Bits of the drug within the capsule break down at different rates so there is a longer duration of action

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5
Q

How does the Na/K ATPase pump use active diffusion

A

The pump moves sodium out of the cell and decreases potassium entering the cell > creates gradient that allows for movement of substances into cell

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6
Q

True or False:
At steady state, even though the blood levels of a drug fluctuate above and below the mean concentration and the drug tends to have peaks and troughs during dosing intervals, the fluctuations remain within a constant range.

A

True

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7
Q

What are the disadvantages of rectal medications?

A

Erratic absorption

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8
Q

Which drug is more easily absorbed in the stomach

A

weak acid drugs

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9
Q

Which of the following statements about elimination is NOT true?
A. Clearance is the most important factor in determining drug dosages
B. Liver, kidneys, GI tract are primary sites of elimination
C. Not all drugs are eliminated by the kidneys
D. The proximal tubule is where active tubular secretion occurs and is poorly developed until about the age of 12

A

D. The proximal tubule is where active tubular secretion occurs and is poorly developed until about the age of 12 years

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10
Q

What are the three classes of pharmacogenomic study?

A

Drug metabolizing pharmacogenetics
Drug transporter pharmacogenetics
Drug target pharmacogenetics

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11
Q

You are about to prescribe a medication that has a high affinity for binding to albumin when it is in the bloodstream. The patient’s albumin level is low. How would this impact the dose prescribed for the patient?

a) The dose would need to be increased
b) The dose would need to be decreased
c) This medication should not be prescribed for this patient

A

B. The dose would need to be decreased

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12
Q

True/False:

Only unbound drugs can be excreted

A

True

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13
Q

Describe the difference between renal clearance and liver clearance

A

Renal clearance: unchanged drug

Liver clearance: via transformation of drug into metabolite(s)

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14
Q
Most drugs are absorbed through the GI tract by:
A. Facilitated diffusion
B. Passive diffusion
C. Active transport
D. pH dependent ionization
A

B. passive diffusion

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15
Q

Explain the difference between phase I and phase II metabolic reactions

A

Phase I: drug converted to metabolite that is more polar or water soluble to ease excretion process
Phase II: drugs that cannot become more water soluble instead conjugate with another substance in order to be excreted

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16
Q

Whats the difference between passive and active diffusion

A

Passive diffusion requires no energy, substance travels on concentration gradient from high to low

Active diffusion requires energy, uses Na/K ATPase pump to move substance

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17
Q

True/False:

The hepatic route of drug elimination often causes nausea/diarrhea

A

True

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18
Q

What are the primary sites of elimination and what are the additional sites?

A

Primary sites: kidneys (urine), liver (biliary), GI tract (feces)
Additional sites: lungs, breast milk, saliva, sweat, hair, skin

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19
Q
\_\_\_\_\_ is the most important concept to consider with long term drug administration:
A. Distribution
B. Clearance
C. Absorption
D. Metabolism
A

B. Clearance

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20
Q

What is half life?

A

The time it takes peak drug level to drop by half from elimination
Related to drugs duration of action

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21
Q

What are the three main factors that effect the rate of metabolism?

A
  1. Age; elderly and young children/infants can’t break down drugs as efficiently
  2. Liver disease ie. cirrhosis, hepatitis
  3. Drug tolerance; liver produces more enzymes to break down drug over time
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22
Q

What is distribution

A

Movement of drug through the body from blood to

  • site of action (receptor site)
  • storage sites (Fat)
  • Elimination sites (kidneys)
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23
Q

An advantage of prescribing a sublingual medication is that the medication is:

a. excreted rapidly
b. has less side effects
c. distributed equally
d. avoids first pass metabolism effect

A

D. Avoids first pass metabolism effect

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24
Q

True/False:

Lipophilic drugs have large volume of distributions

A

TRUE

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25
Q

Phase 1 metabolic reactions are caused by why system of enzymes?

A

CYP450 isoenzyme system

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26
Q

True/False:
The clearance of a drug is affected in patients with impaired kidney function. These patients are at an increased risk for drug toxicity

A

True

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27
Q

At what sites can metabolism occur?

A
Liver (main site)
Intestines
Skin
Lungs
Kidney
Brain
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28
Q

True/False:
Drugs that can’t be made more polar are metabolized by Phase 2 reactions or conjugation reactions and added to bile for excretion through the feces

A

True

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29
Q

Age can affect biotransformation. Which of the following is NOT a true statement?
A. P450, blood-brain barrier, intestinal enzymes, renal system not fully developed in babies up to one year
B. Diminished absorption, distribution, creatinine clearance may occur in older adults
C. Older adults lose 50% of hepatic metabolism ability
D. The renal system is not fully developed until the age of 2 years

A

D. The renal system is not fully developed until the age of 2 years

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30
Q

T/F most drugs are weak acids or weak bases

A

TRUE

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31
Q

T/F Ionized drugs are more lipid soluble

A

FALSE ionized drugs are less lipid soluble bc the charges of the drugs and membrane fats are opposing

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32
Q

If a patient has hypoalbuminemia and is given Drug A, which is highly bound to albumin, what may happen to the drug’s effects?

Select one:
a. Albumin binding does not affect the drug.
b. More of Drug A is free and is therefore able to produce greater effects.
c. The dose of Drug A may need to be increased to address larger volume of distribution.
d. Drug interactions would be unlikely to occur with Drug A.
Feedback

A

B. More of Drug A is free and therefore able to produce greater effects

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33
Q

True/False:

Only highly lipophilic drugs can pass through the blood brain barrier

A

True

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34
Q

What are the two main types of drug binding proteins in the blood?

A
  1. Albumin (most common)

2. Glycoproteins (binding sites for several drugs and increase in inflammatory states)

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35
Q

Therapeutic drug levels are drawn when a drug reaches steady state. Drugs that have a multiple dosing regimen reach steady state

Select one:

a. After the second dose
b. After four to five half-lives
c. When the patient feels the full effect of the drug
d. One hour after IV administration

A

B. After four to five half-lives

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36
Q

What is the disadvantage of intramuscular medications?

A

Irritating

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37
Q

What are the disadvantages of the inhalation route?

A

Goes straight from lungs to heart

Ex. adrenaline used to be used for asthma but was d/c bc then went straight to heart and caused increased HR

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38
Q

What factors affect distribution of a drug?

A
  1. Molecular size; easier for smaller drugs to distribute
  2. Lipid solubility; lipophilic drugs more inclined to distribute
  3. pH/Acidity of environment;
  4. Ionization
  5. Protein binding properties
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39
Q

___________ determines the time taken to reach steady state on multiple dosing

A

Half Life

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40
Q

What is pharmacogenomics?

A

Choosing medications based on one’s unique genetic makeup

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41
Q

True/False:

The larger the volume of distribution of a drug the faster the clearance

A

True

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42
Q

What is a prodrug?

A

Any drug that is a precursor to an active drug

Drug is inactive upon administration and becomes active form through metabolism

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43
Q

What is the major drug binding protein in the bloodstream and where is it produced

A

Albumin; produced in the liver

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44
Q

What is steady state?

A

Drug concentration that is high enough to maintain effect but low enough to prevent toxicity
>rate of absorption and elimination are in equilibrium

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45
Q

Pharmacogenetics VS. Pharmacogenomics

A
Pharmacogenomics = refers to single or a few gene variations on drug therapy
Pharmacogenetics = refers more broadly to the genome-wide effects on drug therapy
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46
Q

What is absorption

A

the rate that a drug leaves the site of administration and passes to the systemic circulation

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47
Q

What factors affect the rate of absorption?

A
  1. Route of administration
  2. Dosage
  3. Lipid solubility
  4. Ionization
  5. Presence/absence of food in GI tract
  6. Size of molecule
  7. Blood flow to the area
  8. Formulation of drug
  9. Mechanics of absorption
  10. Cellular environment
  11. Mechanics of absorption
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48
Q

____________ determines the time it takes to reach steady state

A

Half Life; ~5x half life = steady state

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49
Q

What is the onset of action of intramuscular medications?

A

-15 minutes

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50
Q

what are the two mechanisms by which drugs are transported through membranes

A

active diffusion

passive diffusion

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51
Q

How would a poor nutritional status effect protein binding

A

Less nourishment means less available proteins for binding to drugs
Need lower doses of medications

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52
Q

what can increase drug absorption

A

inhibition of P-glycoprotein
gut wall metabolism
lipophilicity

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53
Q

What are the advantages of intramuscular medications?

A

Provides reservoir for drug; extended duration of action bc absorbed over time

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54
Q

True/False:

In some cases increased metabolism can lead to toxicity of certain drugs

A

True

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55
Q

True/False:

The salt form of a drug can contribute to its bioavailability in solubility

A

True

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56
Q

What is meant by parenteral routes of administration

A

Injection directly into body bypassing skin/mucous membranes; aka outside of alimentary canal
Requires aseptic technique

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57
Q
Which of the following are methods of excretion of drugs:
A. Renal
B. Biliary
C. Fecal
D. Sweat
E. All of the above
A

E. All of the above

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58
Q

True/False:

Drugs are typically administered at intervals close to half life

A

True

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59
Q

Drugs that use CYP 3A4 isoenzymes for metabolism may

Select one:

a. Induce the metabolism of another drug
b. Inhibit the metabolism of another drug
c. Both A and B
d. Neither A nor B

A

C. Both A and B

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60
Q

True/False:

The shorter the half life of a drug, the faster the clearance

A

True

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61
Q
You prescribe a medication for a patient that is typically highly protein bound. The patient's albumin is 2.5g/dL. In terms of drug availability you would:
A. Check the liver/renal function
B. Increase the dose of the medicaiton
C. Decrease the dose of the medication
D. Not give the medication
A

C. Decrease the dose of the medication

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62
Q
What is the goal of drug administration?:
A. Bioavailability
B. Distribution
C. Metabolism
D. Elimination
A

A. Bioavailability

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63
Q

True/False:

Metabolites remain in the collecting tubules and are excreted

A

True

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64
Q

What is the P450 System

A

Large family of enzymes that are responsible for most phase 1 reactions
75% of total drug metabolism

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65
Q

What can decrease drug absorption?

A

too hydrophilic

too lipophilic

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66
Q

______ is the minimum amount of a drug that will have inhibitory effects on the growth of a specific organism
*We want to use the lowest effective dose

A

Minimum inhibitory concentration (MIC)

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67
Q

Accumulation of a drug is detectable if the dosing interval is less than ______ half lives

A

4

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68
Q

True/False: ​

The efficacy of antivirals can vary depending on where its transporter is located?

A

True

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69
Q

True/False:

Orally administered drugs may sometimes bypass the first pass effect and enter straight into the circulation

A

FALSE; orally administered drugs all go through the first pass effect before entering circulation

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70
Q

What is the cell membrane made of

A

phospholipid bi-layer

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71
Q

What are some benefits of pharmacogenomics?

A
  1. Understanding why pt’s with the same disease respond differently to a certain medication
  2. Minimize Adverse drug reactions
  3. Help maximize drug efficacy
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72
Q

Explain Pharmacokinetics VS. Pharmacodynamics

A

Pharmacokinetics (effect of body on drug)
Drug administration > Absorption, Distribution, Metabolism, Elimination > concentration of drug in plasma

Pharmacodynamics (effect of drug on body)
Concentration of drug at site of action > drug effect

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73
Q
Kidney failure would disrupt which phase of pharmacokinetics?
A) Metabolism
B) Distribution
C) Absorption
D) Excretion
A

A. Metabolism

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74
Q
Which routes of drug administration are not subjected to the first pass effect?
A. IV
B. Sublingual
C. Inhalation
D. All of the above
A

D. All of the above

75
Q

What does a small volume of distribution of a drug indicate about its distribution?

A

Small volume of distribution = less drug distribution to tissues and more in the blood

76
Q

What is the onset of action for rectal medications?

A

30 minutes

77
Q

What are the parenteral routes of administration?

A
IV
IM
SubQ
Intrarterial
Intra-articular
78
Q

True/False:

The degree of drug-protein binding present in the bloodstream effects the drugs ability to create an effect

A

TRUE; the more protein binding, the less free drug there is to cause an effect

79
Q

What is elimination/excretion?

A

Process of drugs being transferred from inside the body to outside the body

80
Q

Steady state refers to:
A. The time it takes for half of the drug to be eliminated by the body
B. The concentration that will eventually be achieved when the drug is being administered at a constant rate
C. Rate at which the drug leaves the site of administration and passes to the systemic circulation
D. The time it takes drugs to be completely eliminated by the body

A

B. The concentration that will eventually be achieved when the drug is being administered at a constant rate

81
Q

What tests might we incorporate to determine renal function?

A
BUN
Creatinine & creatinine clearance
Glomerular filtration rate
Albumin to creatinine ratios
Plasma drug concentration
82
Q

Rifampin is a nonspecific CYP450 inducer that may:

a. Lead to toxic levels of rifampin and must be monitored closely
b. Cause toxic levels of drugs, such as oral contraceptives, when coadministered
c. Induce the metabolism of drugs, such as oral contraceptives, leading to therapeutic failure
d. Cause nonspecific changes in drug metabolism

A

c. Induce the metabolism of drugs, such as oral contraceptives, leading to therapeutic failure

83
Q

What are the rectal dosage forms?

A

Suppository in oil form

84
Q

Where does most of the metabolism of a drug occur?

A

Liver

85
Q

What factors affect Vd?

A

Kidney disease; bc fluid is retained and the plasma and extravascular fluid volumes are higher
Liver disease bc protein binding is affected

86
Q

What is normal GFR and at when level would we dose adjust a drug?

A

100-120ml/min

GFR <60 you would adjust

87
Q

Explain why the blood brain barrier is hard for many drugs to cross

A

The blood vessels in the brain are surrounded by two different layers of cells, therefore drugs have to be very fat soluble to get through 2 different cell membranes

88
Q

Explain the distribution pathway that a PO drug could undergo

A

Oral ingestion > is either excreted or crosses membranes in stomach or intestine to hepatic portal vein > enters liver where it could be metabolized > enters blood stream as either metabolite or free drug > could be bound to plasma proteins in bloodstream, enter tissue reservoir, go to site of action or go to kidney > excreted from kidney or reabsorbed into bloodstream

89
Q

Drugs that are highly lipophilic often accumulate where?

A

in fat cells

90
Q

Disadvantages of the oral route?

A

Slow onset of action
GI irritation
Amount absorbed is erratic
Inactivation by liver

91
Q

Once they have been metabolized by the liver, the metabolites may be

Select one:

a. More active than the parent drug
b. Less active than the parent drug
c. Totally “deactivated” so they are excreted without any effect
d. All of the above

A

D. All of the above

92
Q

What happens in biliary secretion of drugs?

A

Bile flows from liver to intestine via biliary drugs; excreted through feces

93
Q

Which routes of administration are not enteral or parenteral?

A
  1. Inhalation
  2. Transdermal “patches”
  3. Topical
94
Q

What is capacity limited protein binding?

A

drugs can only bind to available proteins and this binding changes depending on rate of elimination

95
Q

Does a large volume of distribution indicate that there would be more or less of the drug in the tissues of the body?

A

Large volume of distribution = more drug distribution to tissues and less in blood

96
Q

What is enzyme inhibition?

A

Decrease in CYP450 enzyme action

>drugs will build up with potential for toxicity

97
Q

What is the most important factor in determining drug concentration?

A

Clearance

98
Q

True/False:

Drugs that have longer half lives have a greater risk for toxicity

A

True

99
Q

What factors should be considered in when determining route of administration for a drug?

A
  1. Drug properties; ie. insulin can’t be taken orally bc it is digested in the GI tract
  2. Onset of action; ie. do you need a more immediate effect like for anaphylaxis
  3. Convenience for patient
  4. Cost
100
Q

Factors that affect gastric drug absorption include:

a. Liver enzyme activity
b. Protein-binding properties of the drug molecule
c. Lipid solubility of the drug
d. Ability to chew and swallow

A

C. Lipid solubility of the drug

101
Q

What three processes do the kidneys use for drug secretion/excretion?

A
  1. Glomerular filtration
  2. Tubular reabsorption
  3. Tubular secretion
102
Q

Pharmacogenetic testing is required by the U.S. Food and Drug Administration prior to prescribing:

a. Erythromycin
b. Digoxin
c. Plavix
d. Rifampin

A

C. Plavix

103
Q

What factors affect metabolism?

A
Age
Gender
Drug tolerance
Co-morbidities
Drug-drug interactions
Genetic differences
Diet and environmental factors
Liver dysfunction
104
Q

Which of the following variables is a factor in drug absorption?:

a. The smaller the surface area for absorption, the more rapidly the drug is absorbed.
b. A rich blood supply to the area of absorption leads to better absorption.
c. The less soluble the drug, the more easily it is absorbed.
d. Ionized drugs are easily absorbed across the cell membrane.

A

B. A rich blood supply to the area of absorption leads to better absorption

105
Q

True/False:

Bioavailability is the goal of drug administration

A

True

106
Q
When prescribing medications we must concern ourselves with interactions that may increase the activity of other important CYP450 isoenzymes. This process is called:
A. Glucoronidation
B. Enzyme induction
C. Hydrolysis
D. Enzyme inhibition
A

B. enzyme induction

107
Q

True/False:

Metabolism of a drug cannot destroy of eliminate the drug, only change it

A

True

108
Q

What factors affect bioavailability?

A

How drug is administered
How the drug transports across membranes
How drug is affected by acid environ. in stomach
How the drug is formulated

109
Q

What is meant by enteral routes of administration?

A

administration thru the GI tract

110
Q

What is the onset of action for oral meds

A

-30 minutes

111
Q

What does a metabolic reaction do to a drug?

A

Changes it into an inactive form that is more easily excreted

112
Q

What are the advantages of rectal medications?

A

Can be used with infants

Can be used with unconscious patients

113
Q

True/False:

Excretion can happen by renal or hepatic routes

A

True; among other routes

114
Q

True/False:

At a steady state dose = clearance

A

True

115
Q
Three broad classes of genes exist, which have been recognized to influence how genes interact with a given drug. The role of human variation in genes is known as:
A. drug transporter pharmacogenetics
B. drug eliminating pharmacogenetics
C. drug metabolizing pharmacogenetics
D. drug target pharmacogenetics
A

C. drug metabolizing pharmacogenetics

116
Q

What are factors that affect pharmacokinetics?

A
age
pregnancy
hepatic/ renal disease
drug/food interactions
perfusion of target organs
ethnicity
metabolism
nutritional status
117
Q

Explain glomerular filtration of the kidneys

A

Free drug is filtered along with a high volume of fluid

118
Q

When is it best to measure drug levels and why?

A

Best to measure drug levels at lease 2hrs after PO administration bc this is when it will usually be distributed to tissues
>Some meds take longer

119
Q

What are the 2 main metabolic reactions that drugs can go through?

A
  1. Destructive Rxn or Phase 1

2. Conjugation Rxn or Phase 2

120
Q

What is pharmacokinetics

A

What the body does to the drug

121
Q

Which routes of administration bypass the first pass effect?

A

Parenteral: IV, IM, Subcutaneous
Enteral: Sublingual, rectal
Other: Inhalation, topical, transdermal

122
Q

what is ionization

A

the loss or gain of electrons which alters the charge

123
Q

True/False:

Overweight people store more fat-soluble drugs than thin people

A

TRUE

124
Q

Give some examples of substances that can cause enzyme induction

A
Phenobarbital
Rifampin
Foods
Chemicals
Pollutants
125
Q

What is a metabolite?

A

The transformed version of a drug; is inactive

126
Q

What are the disadvantages of intravenous medications?

A

Most dangerous route

127
Q

True/False:
When the effect of a drug has ended, it does not necessarily mean the drug has been eliminated from the body. Rather it could have just redistributed to other parts of the body (inactive sites)

A

True, such as fat, muscle

128
Q

What is the onset of action of the inhalation route?

A

minutes

ex. bronchodilators

129
Q

True/False:

If a person has poor circulation, drugs will not distribute as well

A

True

130
Q

True/False:

In regards to metabolism, some drugs only need to go through phase 1 reactions, but most need to go through both.

A

TRUE

131
Q

In order for a phase II metabolic reaction to occur what two things are needed?

A
  1. Energy

2. Transfer enzymatic activity

132
Q

When a medication is added to a regimen for a synergistic effect, the combined effect of the drug is:

a. The sum of the effects of each drug individually
b. Greater than the sum of the effects of each drug individually
c. Less than the effect of each drug individually
d. Not predictable, as it varies with each individual

A

B. Greater than the sum of the effects of each drug individually

133
Q

Is elimination faster or slower for drugs that are highly protein bound?

A

Slower

134
Q

What is bioavailability?

A

The percent of unchanged drug that reaches systemic circulation

135
Q

What is volume of distribution?

A

Theoretical measurement of the space in the body available to contain the drug
>compares drug distribution to tissues to amt. in blood

136
Q

What is the onset of action for sublingual medications?

A

Minutes

EX. nitro

137
Q

which drug is more easily absorbed in the intestine

A

weak basic drugs

138
Q
\_\_\_\_\_\_\_ is the movement of a drug from its site of administration into the central compartment and the extent to which this occurs:
A. Distribution
B. Absorption
C. Excretion
D. Metabolism
A

B. Absorption

139
Q

The major reason for not crushing a sustained-release capsule is that, if crushed, the coated beads of the drugs could possibly result in

Select one:

a. Disintegration
b. Toxicity
c. Malabsorption
d. Deterioration

A

B. Toxicity

140
Q

True/False:

The drug absorbed from the mouth and rectum goes to the liver for metabolism

A

FALSE

sublingual meds and rectal suppositories are absorbed directly into bloodstream and into heart

141
Q

What are enteral routes of administration

A

Oral
Sublingual
Rectal

142
Q

What is the first pass effect?

A

First pass of a drug through the liver where it is often metabolized

143
Q

What is the onset of action of subcutaneous medications?

A

-10 miutes

ex insulin, TB

144
Q

What are the 4 phases of pharmacokinetics?

A

Absorption
Distribution
Metabolism (biotransformation)
Elimination/Excretion

145
Q

True/False:

Water soluble drugs would have a volume of distribution similar to plasma volume

A

TRUE; bc most of it stays in the blood anyways

146
Q

A result of upregulation of receptors may cause:

a. A synergistic response to a drug
b. A complete lack of response
c. An exaggerated response if the drug is withdrawn suddenly
d. A complete lack of response if the drug is withdrawn

A

C. An exaggerated response if the drug is withdrawn suddenly

147
Q

Describe the types of destructive metabolic reactions (Phase 1 RXNS)

A
  1. hydrolysis; water is incorporated into structure splitting the molecule
  2. oxidation; hydrogen atoms are remove from the molecule or oxygen atoms are added
  3. reduction; hydrogen atoms are attached to molecule
  4. deamination; nitrogen atoms are removed from molecule
148
Q

Which of the following is never involved in the metabolism of drugs?

a. Liver
b. Blood
c. GI tract
d. Kidneys
e. None of the above

A

E. None of the above

149
Q

True/False:

Protein binding allows for drug distribution as opposed to passive diffusion

A

True

150
Q

Which of the following statements about the major distribution barriers (blood-brain or fetal-placental) is true?:

a. Water soluble and ionized drugs cross these barriers rapidly.
b. The blood-brain barrier slows the entry of many drugs into and from brain cells.
c. The fetal-placental barrier protects the fetus from drugs taken by the mother.
d. Lipid-soluble drugs do not pass these barriers and are safe for pregnant women.

A

B. The blood-brain barrier slows the entry of many drugs into and from brain cells

151
Q
The time it takes for the plasma concentration to be reduced by 50%:
A. Half life 
B. Steady State
C. Minimum effective concentration
D. Saturble elimination
A

A. Half life

152
Q

Which of the following statements is NOT correct about volume of distribution (Vd)?
A. Water soluble drugs have Vd similar to plasma
B. Lipophilic drugs have low Vd
C. Drugs with large Vd concentrate in tissues
D. Drugs with smaller Vd concentrate in plasma

A

B. Lipophilic drugs have low Vd

153
Q

What is the result of Phase 1 metabolic reactions on the drug?

A

Increases polarity and solubility of drug to allow easier excretion

154
Q

True/False:

A drug that is administered IV has 100% bioavailabitity

A

True

155
Q

Factors that may cause variations in drug responsiveness include:
A. Changes in the number or function of receptors
B. Tachyphylaxis
C. Idiosyncratic drug response
D. Hypersensitivity reaction
E. All of the above

A

E. All of the above

156
Q

Which enzymes are responsible for phase I metabolic reactions and which one in particular is the major enzyme responsible for almost 50% of all drug metabolism?

A

CYP450 isoenzymes

>CYP3A4 is responsible for 50% of metabolism

157
Q

Advantages of Oral route

A

safest
convenient
economical
most commonly used

158
Q

True/False:
High protein binding drugs exhibit higher “free” drug concentration in the plasma when albumin and protein levels are low

A

True

159
Q

True/False:
Differences in reaction to the same medication are caused by differences in the drug metabolizing gene expressing CYP450 enzymes.

A

True

160
Q

Main goal of the P450 system

A

Make drugs more water soluble for easier excretion

161
Q

What are the three major families of the P450 system

A

CYP1, CYP2, CYP3

CYP3A4 metabolize half of the drugs in the liver

162
Q

What does a large first pass effect mean and which drugs have this?

A

Means that more of the drug is broken down in the liver

Ex. morphine, diazepam, propranolol

163
Q
Bioavailability of oral drugs can be as low as:
A. 5%
B. 25%
C. 50%
D. 100%
A

A. 5%

164
Q

What is clearance?

A

The sum of all sites of elimination of a drug

  • Important to determine drug concentration
  • Important in regard to toxicity
165
Q

What is the difference between antiseptics and antibiotics?

A

Antibiotics are specific and antiseptics are not specific

Ex. Alcohol is an antiseptic bc it kills everything

166
Q

True/False:

Only a drug that is NOT bound to albumin, in other words a “free” drug can attach to receptors and cause an effect

A

True

167
Q

True or False
If an antibiotic has been shown to slow the growth of a specific bacteria, does this mean that it will also be effective in killing the bacteria?

A

False

168
Q

Ultrarapid metabolizers of drugs may have:

a. To have dosages of drugs adjusted downward to prevent drug accumulation
b. Active drug rapidly metabolized into inactive metabolites, leading to potential therapeutic failure
c. Increased elimination of active, nonmetabolized drug
d. Slowed metabolism of a prodrug into an active drug, leading to an accumulation of prodrug
Feedback

A

B. Active drug rapidly metabolized into inactive metabolites, leading to potential therapeutic failure

169
Q

What is enzyme induction?

A

Increase in CYP450 enzyme action

>causing decreased drug action of the inducer and co-administered drugs

170
Q

Give an example of how competition for protein binding could result in drug toxicity

A

Two highly protein bound drugs can compete for attachment to albumin; this could result in more free drug of whichever drug is competitively blocked from binding to albumin

171
Q

How many half lives does it take to eliminate a drug?

A

5

172
Q

What is the main drug excretion point?

A

Kidneys

173
Q

Why can a generic drug affect a patient differently?:
A. The drug in a generic form can be higher in potency
B. Chemically they are different
C. Molecularly they are different
D. It is not the same drug

A

C. Molecularly they are different

174
Q

True/False:

Genetic variants of a gene can result in normal, reduced, or overactive drug metabolizing enzymes.

A

False

175
Q

True/False:

The biliary secretion route of elimination usually happens with drugs of higher molecular weights

A

True

176
Q

True/False:

To have drugs transported into the cell they must be lipophilic and/or hydrophobic

A

TRUE

177
Q

Explain tubular reabsorption (Proximal tubule) of the kidneys

A

About half of the lipid-soluble drug that has entered the renal tubules is PASSIVELY reabsorbed back into bloodstream along with Na and H2O

178
Q

True/False:
Hydrophilic drugs distribute more easily into extracellular spaces while lipophilic drugs distribute more easily into fat

A

True

179
Q

True/False:

The patient took a BP medication. The drug get excreted by the kidneys. It is an example of pharmacodynamics.

A

False

180
Q

True/False:
Lipid soluble drugs undergo passive reabsorption to get from renal tubules back into bloodstream and may or may not be actively transported back from the blood to the collecting tubules

A

True

181
Q

Explain tubular secretion (Proximal tubule) of the kidneys

A

Certain drugs can be ACTIVELY transported using carrier proteins from the blood directly into the nephron to be quickly excreted
Ex. penicillins undergo tubular secretion process which is why their half life is so short; is not bc they are metabolized quicker than other abx

182
Q

Describe tetracycline in terms of its active and inactive (redistribution) sites

A

Tetracycline is an antibiotic with the active site being bacteria; however it tends to accumulate in tissues containing calcium (bones/teeth) as an inactive site
*This is why is is contraindicated in children with growing bones/teeth and pregnant women

183
Q

When drugs have been metabolized and reach the kidney tubule, if the drug is ionized and lipophilic the drug will tend to:
A. Be passively eliminated in the urine
B. Be actively reabsorbed through the tubular lumen

A

A. Be passively eliminated in the urine

184
Q

What patient factors could effect distribution?

A

Obesity; more drug accumulation in fat stores
Nutritional status
Circulation