Lippincott CHAPTER 1 Pharmacokinetics Flashcards
1
Q
describes what the drug does to
the body.
a. Pharmacokinatics
b. pharmacodynamic
A
b. pharmacodynamic
2
Q
refers to what the body does to a drug
a. Pharmacokinetics
b. pharmacodynamics
A
a. Pharmacokinetics
3
Q
what are the four pharmacokinetic properties that determine the onset, intensity, and duration of drug action
A
absorption
distribution
metabolism
elimination
4
Q
What is pharmacokinetics?
What the drug does to the body.
What the body does to a drug.
The study of diseases.
The study of the effect of drugs on society.
A
b. What the body does to a drug.
5
Q
What are the four pharmacokinetic properties that determine the onset, intensity, and duration of drug action?
Absorption, distribution, metabolism, and elimination.
Absorption, excretion, inhalation, and distribution.
Metabolism, absorption, excretion, and distribution.
Elimination, distribution, inhalation, and absorption.
A
a. Absorption, distribution, metabolism, and elimination.
6
Q
Why is the route of administration important in drug regimens?
It determines the color of the pill.
It determines the taste of the drug.
It determines the therapeutic objectives.
It determines the price of the drug.
A
c. It determines the therapeutic objectives.
7
Q
What are the major routes of drug administration?
Enteral, parenteral, and topical.
Oral, nasal, and injection.
Ocular, aural, and vaginal.
Rectal, sublingual, and transdermal.
A
a. Enteral, parenteral, and topical.
8
Q
What is the function of absorption in pharmacokinetics?
To distribute the drug into the interstitial and intracellular fluids.
To eliminate the drug and its metabolites from the body.
To biotransform the drug through metabolism by the liver or other tissues.
To permit entry of the drug (either directly or indirectly) into plasma.
A
d.
To permit entry of the drug (either directly or indirectly) into plasma.
9
Q
What is enteral administration?
Administering a drug through the skin
Administering a drug through the nose
Administering a drug by mouth
Administering a drug through the veins
A
c. Administering a drug by mouth
10
Q
What are the advantages of oral administration?
Oral drugs are easily self-administered, and toxicities and/or overdose of oral drugs may be overcome with antidotes, such as activated charcoal.
Oral drugs require a lower dose than other methods
Oral drugs are faster acting than other methods
Oral drugs have a lower risk of side effects than other methods
A
a. Oral drugs are easily self-administered, and toxicities and/or overdose of oral drugs may be overcome with antidotes, such as activated charcoal.
11
Q
What is an enteric-coated preparation?
A drug that is administered through the skin
A drug that is administered through the nose
A chemical envelope that protects the drug from stomach acid, delivering it instead to the less acidic intestine, where the coating dissolves and releases the drug
A drug that is injected directly into the bloodstream
A
c.
A chemical envelope that protects the drug from stomach acid, delivering it instead to the less acidic intestine, where the coating dissolves and releases the drug
12
Q
What are the advantages of extended-release formulations?
They allow for slower absorption and prolonged duration of action.
They have a lower risk of side effects than other formulations
They are more convenient to administer than other formulations
They are faster acting than other formulations
A
a. They allow for slower absorption and prolonged duration of action.
13
Q
What is the sublingual route of absorption?
Placement of drug under the tongue
Placement of drug between the cheek and gum
Injection of drug into the bloodstream
Administration of drug through the skin
A
a.
Placement of drug under the tongue
14
Q
What is the parenteral route of drug administration?
The route that introduces drugs directly into the systemic circulation
The route that introduces drugs into the gastrointestinal tract
The route that introduces drugs into the lungs
The route that introduces drugs into the skin
A
a.
The route that introduces drugs directly into the systemic circulation
15
Q
Why is parenteral administration used?
For drugs that are poorly absorbed from the gastrointestinal tract or unstable in the gastrointestinal tract, and for patients unable to take oral medications
For drugs that are well absorbed from the gastrointestinal tract and stable in the gastrointestinal tract, and for patients able to take oral medications
For drugs that are poorly absorbed from the lungs or unstable in the lungs, and for patients unable to inhale medications
For drugs that are well absorbed from the skin or unstable in the skin, and for patients unable to apply topical medications
A
a.
For drugs that are poorly absorbed from the gastrointestinal tract or unstable in the gastrointestinal tract, and for patients unable to take oral medications
16
Q
What are the four major parenteral routes?
Intravascular, intramuscular, subcutaneous, and intradermal
Intravascular, intramuscular, oral, and intradermal
Oral, intramuscular, subcutaneous, and intradermal
Intravascular, inhalation, subcutaneous, and intradermal
A
a.
Intravascular, intramuscular, subcutaneous, and intradermal
17
Q
What is the most common parenteral route of drug administration?
Intravascular
Intramuscular
Subcutaneous
Intravenous
A
d. Intravenous
18
Q
Which parenteral route provides the most control over the dose of drug delivered to the body?
Intravascular
Intramuscular
Subcutaneous
Intravenous
A
d. Intravenous
19
Q
What is the advantage of using inhalation and nasal routes for drug administration?
They provide slow delivery of drug.
They deliver drugs to the site of action, minimizing systemic side effects.
They are not effective for patients with respiratory disorders.
They are not convenient for patients.
A
b.
They deliver drugs to the site of action, minimizing systemic side effects.
20
Q
When are intrathecal/intraventricular routes of administration necessary?
When local, rapid effects are not needed.
When the drug needs to be absorbed into the bloodstream.
When the blood-brain barrier delays or prevents drug absorption into the CNS.
When the drug is a gas.
A
c.
When the blood-brain barrier delays or prevents drug absorption into the CNS.
21
Q
When is topical application of drugs used?
When a systemic effect of the drug is desired.
When a local effect of the drug is desired.
When the drug is a gas.
When the drug is administered via a transdermal patch.
A
b.
When a local effect of the drug is desired.
22
Q
How does transdermal administration achieve systemic effects?
By introducing drugs directly into the cerebrospinal fluid.
By delivering drugs to the site of action, minimizing systemic side effects.
By application of drugs to the skin via a transdermal patch.
By preventing destruction of the drug in the GI environment.
A
c.
By application of drugs to the skin via a transdermal patch.
23
Q
What is an advantage of rectal administration?
It is the fastest route of administration.
It delivers drugs to the site of action, minimizing systemic side effects.
It minimizes the biotransformation of drugs by the liver.
It is not useful if the patient is already vomiting.
A
c.
It minimizes the biotransformation of drugs by the liver.
24
Q
Which route of administration is often used for patients with allergic rhinitis?
Oral inhalation
Intrathecal/intraventricular
Topical
Nasal
A
d.
Nasal
25
What is bioavailability?
The rate and extent of absorption of a drug.
The transfer of a drug from the site of administration to the bloodstream.
The percentage of the administered drug that reaches the systemic circulation.
The time it takes for a drug to reach its peak concentration in the bloodstream.
c.
The percentage of the administered drug that reaches the systemic circulation.
26
Which route of administration is useful if the patient is unconscious or if the drug induces vomiting when given orally?
Oral inhalation
Intrathecal/intraventricular
Rectal
Transdermal
c.
Rectal
27
How does the rate of absorption vary in transdermal administration?
It is constant and does not depend on the physical characteristics of the skin.
It is faster if the drug is less lipid-soluble.
It can vary markedly depending on the physical characteristics of the skin at the site of application and the lipid solubility of the drug.
It is slower than other routes of administration.
It can vary markedly depending on the physical characteristics of the skin at the site of application and the lipid solubility of the drug.
28
Which route of administration provides the most rapid drug effects?
Oral inhalation
Intrathecal/intraventricular
Rectal
IV bolus
d.
IV bolus
29
from the site of administration permits
entry of the drug (either directly or indirectly) into plasma
a. absorption
b. distribution
c. metabolism
d. elimination
a. absorption
30
the drug may reversibly leave the bloodstream
and distribute into the interstitial and intracellular fluids.
a. absorption
b. distribution
c. metabolism
d. elimination
b. distribution
31
the drug may be biotransformed through metabolism by the liver or other tissue
a. absorption
b. distribution
c. metabolism
d. elimination
c. metabolism
32
the drug and its metabolites are eliminated from
the body in urine, bile, or feces.
a. absorption
b. distribution
c. metabolism
d. elimination
d. elimination
33
is the most
common, convenient, and economical method of drug administration
a. enteral
b. parenteral
a. enteral
34
The drug may be swallowed, allowing oral delivery, or it may be
placed under the tongue {sublingual) or between the gums and cheek
{buccal), facilitating direct absorption into the bloodstream.
a. enteral
b. parenteral
a. enteral
35
what are the enteral routes of administration?
a. oral
b. sublingual / buccal
36
what drugs are placed under the tongue ?
a. sublingual
b. buccal
sublingual
37
what drugs are put between the gums and cheek
a. sublingual
b. buccal
b. buccal
38
drugs are easily self-administered, and toxicities and/or overdose of oral drugs may be overcome with antidotes, such as
activated charcoal.
a. oral
b. sublingual/buccal
a. oral
39
the pathways involved in this route of administration of
drug absorption are the most complicated, and the low gastric
pH inactivates some drugs
a. oral
b. buccal/sublingual
a. oral
40
is a chemical envelope that protects the drug from stomach acid, delivering it instead to the less acidic intestine, where the coating
dissolves and releases the drug.
a. enteric coated preparation
b. extended release preparation
a. enteric coated preparation
Enteric coating is useful
for certain drugs {for example, omeprazole) that are acid
labile, and for drugs that are irritating to the stomach, such
as aspirin.
41
its abbreviations are ER, XR, XL, SR, etc.
a. enteric coated preparation
b. extended release preparation
b. extended release preparation
42
medications have special
coatings or ingredients that control drug release, thereby
allowing for slower absorption and prolonged duration of
action.
a. enteric coated preparation
b. extended release preparation
b. extended release preparation
43
formulations can be dosed less frequently and
may improve patient compliance.
a. enteric coated preparation
b. extended release preparation
b. extended-release preparation
44
these drug formulations are
advantageous for drugs with short half-lives and may maintain concentrations within the therapeutic
range over a longer duration.
a. enteric coated preparation
b. extended release preparation
b. extended release preparation
For example,
the half-life of oral morphine is 2 to 4 hours, and it must be
administered six times daily to provide continuous pain relief.
However, only two doses are needed when extended-release
tablets are used.
45
This route involves placement of
drug under the tongue.
a. sublingual
b. buccal
a. sublingual
46
This drug involves placement of
drug between the cheek and gum
a. sublingual
b. buccal
b. buccal
47
routes of absorption have several advantages, including ease of
administration, rapid absorption, bypass of the harsh gastrointestinal {GI) environment, and avoidance of first-pass metabolism
a. oral
b. sublingual/ buccal
b. sublingual/ buccal
48
route introduces drugs directly into the systemic circulation
a. enteral
b. parenteral
b. parenteral
49
is used for drugs that are poorly
absorbed from the Gl tract (for example, heparin) or unstable in
the Gl tract (for example, insulin)
a. enteral
b. parenteral
b. parenteral
50
administration is also
used for patients unable to take oral medications (unconscious
patients) and in circumstances that require a rapid onset of action.
a. enteral
b. parenteral
b. parenteral
51
administration provides the most control over the dose
of drug delivered to the body. However, this route of administration
is irreversible and may cause pain, fear, local tissue damage, and
infections.
a. enteral
b. parenteral
b. parenteral
52
what are the four major parenteral routes
intravascular (intravenous or intra-arterial), intramuscular, subcutaneous, and intradermal
53
is the most common parenteral
route.
a. intravenous
b. intramuscular
c. subcutaneous
d. intradermal
a. intravenous
54
It is useful for drugs that are not absorbed orally, such as
the neuromuscular blocker rocuronium
a. intravenous
b. intramuscular
c. subcutaneous
d. intradermal
a. intravenous
55
permits a rapid
effect and a maximum degree of control over the amount of drug
delivered.
a. intravenous
b. intramuscular
c. subcutaneous
d. intradermal
a. intravenous
56
when this kind of intravenous administration is used the full amount of drug is
delivered to the systemic circulation almost immediately
a. IV bolus
b. IV infusion
a. IV bolus
57
when this kind of intravenous administration is used the drug is infused over a longer period,
resulting in lower peak plasma concentrations and an increased
duration of circulating drug.
a. IV bolus
b. IV infusion
b. IV infusion
58
when this kind of intramuscular administration is used this is absorbed rapidly
a. aqueous solution
b. depot preparation
a. aqueous solution
59
when this kind of intramuscular administration is used it is absorbed slowly
a. aqueous solution
b. depot preparation
b. depot preparation
60
often consist of a suspension of drug in a nonaqueous vehicle,
such as polyethylene glycol.
a. aqueous solution
b. depot preparation
b. depot preparation
As the vehicle diffuses out of the
muscle, drug precipitates at the site of injection. The drug then
dissolves slowly, providing a sustained dose over an extended
interval.
61
injection provides
absorption via simple diffusion and is slower than the IV route.
a. intravenous
b. intramuscular
c. subcutaneous
d. intradermal
c. subcutaneous
62
injection minimizes the risks of hemolysis or thrombosis
associated with IV injection and may provide constant, slow, and
sustained effects.
a. intravenous
b. intramuscular
c. subcutaneous
d. intradermal
c. subcutaneous
63
This route should not be used with drugs that
cause tissue irritation, because severe pain and necrosis may
occur.
a. intravenous
b. intramuscular
c. subcutaneous
d. intradermal
c. subcutaneous
64
route involves injection into
the dermis, the more vascular layer of skin under the epidermis.
a. intravenous
b. intramuscular
c. subcutaneous
d. intradermal
d. intradermal
65
Agents for diagnostic determination and desensitization are usually administered by this route
a. intravenous
b. intramuscular
c. subcutaneous
d. intradermal
d. intradermal
66
This administration provide rapid delivery of
drug across the large surface area of mucous membranes of
the respiratory tract and pulmonary epithelium
a. oral inhalation and nasal preparation
b. intrathecal/ intraventricular
c. topical
d. transdermal
a. oral inhalation and nasal preparation
67
Drug effects are
almost as rapid as are those with IV bolus. Drugs that are gases
(for example, some anesthetics) and those that can be dispersed
in an aerosol are administered via
a. oral inhalation and nasal preparation
b. intrathecal/ intraventricular
c. topical
d. transdermal
a. oral inhalation and nasal preparation
68
This route is effective and convenient for patients with respiratory disorders such as
asthma or chronic obstructive pulmonary disease, because drug
is delivered directly to the site of action, thereby minimizing systemic side effects.
a. oral inhalation and nasal preparation
b. intrathecal/ intraventricular
c. topical
d. transdermal
a. oral inhalation and nasal preparation
The nasal route involves topical administration
of drugs directly into the nose, and it is often used for patients with
allergic rhinitis.
69
The blood-brain barrier typically
delays or prevents the absorption of drugs into the central nervous
system (CNS). When local, rapid effects are needed, it is necessary to introduce drugs directly into the cerebrospinal fluid.
a. oral inhalation and nasal preparation
b. intrathecal/ intraventricular
c. topical
d. transdermal
b. intrathecal/ intraventricular
70
application is used when a local effect of the drug
is desired.
a. oral inhalation and nasal preparation
b. intrathecal/ intraventricular
c. topical
d. transdermal
c. topical
71
This route of administration achieves systemic
effects by application of drugs to the skin, usually via a transdermal patch
a. oral inhalation and nasal preparation
b. intrathecal/ intraventricular
c. topical
d. transdermal
d. transdermal
The rate of absorption can vary markedly,
depending on the physical characteristics of the skin at the site of
application, as well as the lipid solubility of the drug.
72
Because 50% of the drainage of the rectal region bypasses
the portal circulation, the biotransformation of drugs by the liver is
minimized with this administration.
a. intrathecal/ intraventricular
b. topical
c. transdermal
d. rectal
d. rectal
73
route has the additional advantage of preventing destruction of the drug in the Gl environment.
a. intrathecal/ intraventricular
b. topical
c. transdermal
d. rectal
d. rectal
74
This route is also useful if the drug induces vomiting when
given orally, if the patient is already vomiting, or if the patient is unconscious. This route of absorption is often erratic and incomplete, and many
drugs irritate the rectal mucosa
a. intrathecal/ intraventricular
b. topical
c. transdermal
d. rectal
d. rectal
75
is the transfer of a drug from the site of administration to the
bloodstream.
a. absorption
b. distribution
c. metabolism
d.excretion
a. absorption
The rate and extent of absorption depend on the environment where the drug is absorbed, chemical characteristics of the drug,
and the route of administration (which influences bioavailability). Routes
of administration other than intravenous may result in partial absorption
and lower bioavailability.
76
safest and most common , convenient , and economical route of administration
a. oral
b. sublingual
c. intravenous
d. intramuscular
a.oral
77
-Limited absorption of some drugs.
-food may affect absorption .
-patient compliance is necessary
-drugs may be metabolized before systemic absorption
a. oral
b. sublingual
c. intravenous
d. intramuscular
a. oral
78
Depends on the drug:
Few drugs ( for example nitroglycerin) have rancid, direct systemic absorption.
- Most drugs eratically or incompletely absorbed
a. oral
b. sublingual
c. intravenous
d. intramuscular
b. sublingual
79
By passes first pass effect
-Bypasses destruction by stomach acid
-Drug stability maintained because pH of saliva relatively neutral
-May cause immediate pharmacological effects
a. oral
b. sublingual
c. intravenous
d. intramuscular
b. sublingual
80
-Limited to certain types of drugs
-Limited to drugs that can be taken in small doses
-May lose part of the drig dose if swallowed
a. oral
b. sublingual
c. intravenous
d. intramuscular
b. sublingual
81
absorption not required
a. oral
b. sublingual
c. intravenous
d. intramuscular
c. intravenous
82
can be immediate effects
-ideal if dose in large volumes
-suitable for irritating substances and complex mixtures
- valuable in emergency situation
-dosage titration permissible
-Ideal for high molecular weight proteins and peptide drugs
a. oral
b. sublingual
c. intravenous
d. intramuscular
c. intravenous
83
unsuitable for oily substances
- bolus injection may result in adverse effects
- most substances must be slowly injected
-strict aseptic techniques needed
a. oral
b. sublingual
c. intravenous
d. intramuscular
c. intravenous
84
what are the two diluents of intramuscular
-aqueus solution
-depot preparation
85
what intramuscular diluent is prompt?
a. aqueus solution
b. depot preparation
a. aqueus solution
86
what intramuscular diluent is slow and sustained?
a. aqueus solution
b. depot preparation
b. depot preparation
87
-suitable if drug volume is moderate
- suitable for oily vehicles and certain irritable substances
- preferable to intravenous if patient must self-administer
a. oral
b. sublingual
c. intravenous
d. intramuscular
d. intramuscular
88
-affects certain lab tests ( creatinine kinase )
a. oral
b. sublingual
c. intravenous
d. intramuscular
d. intramuscular
89
-can be painful
- can cause intramuscular hemorrhage (precluded during anticoagulation therapy )
a. oral
b. sublingual
c. intravenous
d. intramuscular
d. intramuscular
90
-suitable for slow release drugs
- ideal for some poorly soluble suspensions
a. subcutaneous
b. inhalation
c. topical
d. transdermal (patch)
e. rectal
a. subcutaneous
91
pain or necrosis if drug is irritating
-unsuitable for drugs administered in large volumes
a. subcutaneous
b. inhalation
c. topical
d. transdermal (patch)
e. rectal
a. subcutaneous
92
systemic absorption may occur; this is not always desirable
a. subcutaneous
b. inhalation
c. topical
d. transdermal (patch)
e. rectal
b. inhalation
93
-absorption is rapid; can have immediate effects
-ideal for gases
-effective for patients with respiratory problems
-dose can be titrated
-localized effect to target lungs; lower doses used compared to that with oral or parenteral administration
-fewer systemic side effects
a. subcutaneous
b. inhalation
c. topical
d. transdermal (patch)
e. rectal
b. inhalation
94
most addictive route (drug can enter the brain quickly)
-patient may have difficult regulating dose
a. subcutaneous
b. inhalation
c. topical
d. transdermal (patch)
e. rectal
b. inhalation
95
variable; affected by skin condiion , area of skin and other factors
a. subcutaneous
b. inhalation
c. topical
d. transdermal (patch)
e. rectal
c. topical
96
suitablewhen local effect of drug is desired
-may be used for skin , eye , intravaginal and intranasal products
-minimizes systemic absorption
-easy for patient
a. subcutaneous
b. inhalation
c. topical
d. transdermal (patch)
e. rectal
c. topical
97
-some systemic absorption can occur
-unsuitable for drugs with high molecular weight or poor lipid solubility
a. subcutaneous
b. inhalation
c. topical
d. transdermal (patch)
e. rectal
c. topical
98
slow and sustained
a. subcutaneous
b. inhalation
c. topical
d. transdermal (patch)
e. rectal
d.transdermal patch
99
-bypasses the first pass effect
-convenient and painless
-ideal for drugs that are lipophilic and have poor oral bioavailability
-ideal for drugs that are quickly eliminated from the body
a. subcutaneous
b. inhalation
c. topical
d. transdermal (patch)
e. rectal
d. transdermal (patch)
100
-some patients are allergic to this, which can cause irritation
-drug must be highly lipophilic
-may cause delayed delivery of drug to pharmacological site of action
-limited to drugs that can be taken in small daily doses
a. subcutaneous
b. inhalation
c. topical
d. transdermal (patch)
e. rectal
d. transdermal (patch)
101
erratic and variable
a. subcutaneous
b. inhalation
c. topical
d. transdermal (patch)
e. rectal
e. rectal
102
-partially bypasses first pass effect
- by passes destruction by stomach acid
-ideal id drug causes vomiting
-ideal in patients who are vomiting, or comatose
a. subcutaneous
b. inhalation
c. topical
d. transdermal (patch)
e. rectal
e. rectal
103
-drugs may irritate the rectal mucosa
- not a well accepted route
a. subcutaneous
b. inhalation
c. topical
d. transdermal (patch)
e. rectal
e. rectal
104
what are the mechanisms of absorption of drugs form the GI tract
a. passive diffusion
b. facilitated diffusion
c. active transport
d. endocytosis and exocytosis
105
: The driving force for this of a
drug is the concentration gradient across a membrane separating
two body compartments. In other words, the drug moves from an
area of high concentration to one of lower concentration
a. passive diffusion
b. facilitated diffusion
c. active transport
d. endocytosis and exocytosis
a. passive diffusion
106
does not involve a carrier, is not saturable, and shows
low structural specificity. The vast majority of drugs are absorbed
by this mechanism.
a. passive diffusion
b. facilitated diffusion
c. active transport
d. endocytosis and exocytosis
a. passive diffusion
Water-soluble drugs penetrate the cell membrane through aqueous channels or pores, whereas lipid-soluble
drugs readily move across most biologic membranes due to solubility in the membrane lipid bilayers
107
Water-soluble drugs penetrate the cell membrane through
a. aqueous channel or pores
b. membrane lipid bilayers
a. aqueous channel or pores
108
lipid-soluble
drugs readily move across most biologic membranes due to solubility in
a. aqueous channel or pores
b. membrane lipid bilayers
b. membrane lipid bilayers
109
Other agents can enter the cell through
specialized transmembrane carrier proteins that facilitate the passage of large molecules.
a. passive diffusion
b. facilitated diffusion
c. active transport
d. endocytosis and exocytosis
b. facilitated diffusion
110
These carrier proteins undergo conformational changes, allowing the passage of drugs or endogenous
molecules into the interior of cells. This process is known as
a. passive diffusion
b. facilitated diffusion
c. active transport
d. endocytosis and exocytosis
b. facilitated diffusion
111
It does not require energy, can be saturated, and
may be inhibited by compounds that compete for the carrier.
a. passive diffusion
b. facilitated diffusion
c. active transport
d. endocytosis and exocytosis
b. facilitated diffusion
112
This mode of drug entry also involves specific
carrier proteins that span the membrane. It is energy dependent, driven by the hydrolysis of adenosine
triphosphate (ATP).
a. passive diffusion
b. facilitated diffusion
c. active transport
d. endocytosis and exocytosis
c. active transport
113
It is capable of moving drugs against a concentration gradient, from a region of low drug concentration to one
of higher concentration. The process is saturable.
a. passive diffusion
b. facilitated diffusion
c. active transport
d. endocytosis and exocytosis
c. active transport
114
The process is saturable. ____are selective and may be competitively inhibited by other
cotransported substances.
a. passive diffusion
b. facilitated diffusion
c. active transport
d. endocytosis and exocytosis
c. active transport
115
This type of absorption is used to
transport drugs of exceptionally large size across the cell membrane.
a. passive diffusion
b. facilitated diffusion
c. active transport
d. endocytosis and exocytosis
d. endocytosis and exocytosis
116
involves engulfment of a drug by the cell membrane and transport into the cell by pinching off the drug-filled
vesicle
a. endocytosis
b. exocytosis
a. endocytosis
. Many cells use
exocytosis to secrete substances out of the cell through a similar
process of vesicle formation.
117
Vitamin 812 is transported across the
gut wall by
a. endocytosis
b. exocytosis
a. endocytosis
118
certain neurotransmitters (for
example, norepinephrine) are stored in intracellular vesicles in the
nerve terminal and released by
a. endocytosis
b. exocytosis
b. exocytosis
119
what are the factors influencing absorption
1. Effect of pH on drug absorption
2. Blood flow to the absorption site
3. Total surface area available for absorption
4. Contact time at the absorption surface
5. Expression of P-glycoprotein:
120
what will an acidic drug release?
acidic drug(HA)
it will release
proton (H+)
charged anion (A-)
HA <-> H+ + A-
121
what will weak bases drug release
weak bases (BH+)
will release:
H+
uncharged base (B)
BH+ <-> B + H+
122
Pharmacodynamics refers to:
A) How the drug is absorbed in the body
B) How the body reacts to a drug
C) How the body metabolizes a drug
D) How the drug is excreted from the body
E) What the drug does to the body
----------
E) What the drug does to the body
123
Which of the following determines the onset, intensity, and duration of drug action?
A) How the drug is absorbed in the body
B) Pharmacodynamics
C) Pharmacokinetics
D) How the drug is excreted from the body
E) Both pharmacokinetics and pharmacodynamics
----------
E) Both pharmacokinetics and pharmacodynamics
124
What aspect of drug action do pharmacodynamics describe?
A) How the body eliminates the drug
B) How the body absorbs the drug
C) How the drug is metabolized
D) How the drug affects the body
E) How the body breaks down the drug
----------
D) How the drug affects the body ✔
125
What determines the onset, intensity, and duration of drug action?
A) Drug metabolism
B) Pharmacodynamics
C) Drug absorption
D) Pharmacokinetic properties
E) Drug elimination
----------
D. pharmacokinetic properties
126
LOW pKa
a. acidic
b. basic
a. acidic
127
HIGH pKa
a. acidic
b. basic
b. basic
128
what is the formula of ionization constant
a. pKa
b. pH
a. pKa
129
determined by the pH at the site of absorption and by
the strength of the weak acid or base, which is represented by the
a. pKa
b. pH
a. pKa/ ionization constant
130
is a measure
of the strength of the interaction of a compound with a proton
a. pKa
b. pH
a. pKa
Distribution equilibrium
is achieved when the permeable form of a drug achieves an equal
concentration in all body water spaces.
131
a. The intestines receive much
more blood flow than does the stomach
b. The stomach receive much
more blood flow than does the small intestine
a. The intestines receive much
more blood flow than does the stomach
[Note: Shock severely
reduces blood flow to cutaneous tissues, thereby minimizing
absorption from SC administration.]
132
: With a surface rich
in brush borders containing microvilli, making absorption of
the drug across the this more efficient.
a .stomach
b. intestine
b. intestine
133
134
The presence of food
a. absorb drug more quickly
b. absorb drugs slowly
b. absorb drugs slowly
anything that
delays the transport of the drug from the stomach to the intestine delays the rate of absorption
135
areas of high expression, P-glycoprotein
____ drug absorption
a. increases
b. decreases
b. decreases
In addition to transporting many drugs
out of cells, it is also associated with multidrug resistance.
136
is the rate and extent to which an administered
drug reaches the systemic circulation
a. Bioequivalence
b. bioavailability
b. bioavailability
137
If the drug
is rapidly metabolized in the liver or gut wall during this initial passage, the amount of unchanged drug entering the
systemic circulation is decreased. This is referred to as
a. first pass metabolism
b. second pass metabolism
a. first pass metabolism.
more than 90% of nitroglycerin is cleared during
first-pass metabolism. Hence, it is primarily administered
via the sublingual, transdermal, or intravenous route.
138
a very hydrophilic drugs are ___ absorbed
a. highly
b. poorly
b. poorly
because of the inability to cross lipid-rich cell membranes
139
extremely lipophilic are
also ____ absorbed
a. highly
b. poorly
b. poorly
because they are insoluble in aqueous
body fluids and, therefore, cannot gain access to the surface of
cells.
For a drug to be readily absorbed, it must be largely lipophilic, yet have some solubility in aqueous solutions. This is one
reason why many drugs are either weak acids or weak bases.
140
is the process by which a drug reversibly leaves the
bloodstream and enters the extracellular fluid and tissues
a. drug distribution
b. drug absorption
a. drug distribution
141
High blood flow, together with
high lipophilicity of propofol, permits rapid distribution into the CNS
and produces anesthesia
a. true
b. false
a. true
142
is the major drug binding protein, and it may act as a drug reservoir.
a. albumin
b. hemoglobin
a. albumin
143
the metabolite of cyclophosphamide, can
cause hemorrhagic cystitis because it accumulates in the bladder.
a. levodopa
b. acrolein
b. acrolein
144
what is the formula of volume of distribution
Vd = Amount of drug in the body
_____________________
Co
145
is defined as the fluid volume
that is required to contain the entire drug in the body at the same
concentration measured in the plasma
a. volume of distribution
b. bioavailability
a. volume of distribution
146
what is the type of distribution of heparin
a. plasma compartment
b. extracellular fluid
c. total body water
a. plasma compartment
147
what is the type of distribution of aminoglycoside
a. plasma compartment
b. extracellular fluid
c. total body water
b. extracellular fluid
148
what is the type of distribution of ethanol
a. plasma compartment
b. extracellular fluid
c. total body water
c. total body water
Note: In general, a larger
Vd indicates greater distribution into tissues; a smaller Vd suggests confinement to plasma or extracellular fluid
149
INCREASE molecular weight or INCREASE protein bound = trapped plasma concentration
a. INCREASE Vd
b. DECREASE Vd
b. DECREASE Vd
150
Is ussually a first order process allows circulation of Vd
a. drug clearance
b. half life
a. drug clearance
151
what is the formula of Vd
Vd= Dose
____________
Co
152
what is the formula of half life
0.693Vd
__________
Cl
153
, if 1 0 mg of drug is injected into a patient and the plasma
concentration is extrapolated back to time zero, and C0 = 1 mg/L
then what is the Vd?
V d = 1 0 mg/1 mg/L = 1 0 L
154
INCREASE Vd = ___ half life
a. INCREASE
b. DECREASE
a. increase
Therefore, any factor that increases Vd can
increase the half-life and extend the duration of action of the drug.
[Note: An exceptionally large Vd indicates considerable sequestration of the drug in some tissues or compartments.]
155
what are the three major routes of elimination
hepatic metabolism, billary elimination , urinary excretion
156
is irreversible removal of drug from the body
a. elimination
b. half life
a. elimination
157
is removal of intact drug from the body
a. excretion
b. distribution
a. excretion
158
results in products with increased polarity, which allows the drug
to be eliminated
a. metabolism
b. clearance
a. metabolism
159
estimates the volume of blood form which the drug is cleared per unit time
a. metabolism
b. clearance
b. clearance
160
what is the formula of clearance
CL= 0.693 x Vd / t1/2
161
what are the kinetic metabolism
first order kinetic
zero order kinetics
162
aspirin
a.first order kinetic
b.zero order kinetics
b. zero order kinetic
163
ethanol
a.first order kinetic
b.zero order kinetics
b. zero order kinetics
164
phenytoin
a.first order kinetic
b.zero order kinetics
b. zero order kinetics
165
the doses are very large. therefore, the plasma drug concentration is much greater than Km, and drug metabolism is
a.first order kinetic
b.zero order kinetics
b. zero order kinetics
166
constant and independent of the drug dose
a.first order kinetic
b.zero order kinetics
b. zero order kinetics
167
with most drug plasma drug concentration is less than Km, and drug elimination is
a.first order kinetic
b.zero order kinetics
a. first order kinetics
168
proportional to drug dose
a.first order kinetic
b.zero order kinetics
a. first order kinetics
169
The metabolic transformation of drugs is
catalyzed by enzymes
a. first order kinetics
b. zero order kinetics
a. first order kinetics
170
most of the reaction obey Michaelis menten kinetics
a. first order kinetics
b. zero order kinetics
a. first order kinetics
171
what is the formula of first order kinetics
v= rate of drug metabolism
=Vmax(C)
_______
Km
That is, the rate of drug metabolism and elimination is directly proportional to the concentration of free drug, and first-order kinetics
is observed
172
linerar kinetics
a. first order kinetics
b. zero ordre kinetics
a. first order kinetics
173
(C) is much more greater than Km
a. first order kinetics
b. zero order kinetics
b. zero order kinetics
174
what is the formula of zero order kinetics
v=rate of drug metabolism
= Vmax (C)
_________
(C)
= Vmax
175
the enzyme is saturated by a high free drug concentration and the rate of metabolism remains constant over time.
a. firs order kinetics
b. zero order kinetics
b. zero order kinetics
176
nonlinear kinetics
a. first order kinetics
b. zero order kinetics
b. zero order kinetics
177
the rate of elimination is constant does not depe nd on the drug concentration
a. first order kinetics
b. zero order kinetics
b. zero order kinetics
178
the kidney cannot efficiently excrete liphophilic drugs that readily cross the cell membranes ans are reabsorbed in the
a. proximal convoluted tubule
b. distal convoluted tubule
b. distal convoluted tubule
179
phase 1 reaction convert lipophilic drugs into more polar molecules by introducing or unmasking a polar functional group, such as
-OH or - NH2
180
phase 1 reaction involves what reaction
reduction, oxidation , hydrolysis
181
what reaction is most frequently involved in drug metabolism are catalyzed by the cytochrome P 450 (CYP) system.
a. phase 1 reaction
b. phase 2 reaction
a. phase 1 reaction
182
is a superfamily of heme containing isozymes located in most cells, but primarily in the liver and GI tract
a. CYP
b. ATP
a. CYP
183
what type of CYP does chlorpromazine be metabolize
a. CYP3A4
b. CYP2D6
a. CYP3A4
184
what type of CYP does clonazepam be metabolize
a. CYP 3A4
b. CYP 2C
a. CYP3A4
185
what type of CYP does clopidogrel be metabolize
a. CYP 3A4
b. CYP 2C
b. CYP2C
186
phenobarbital
a. CYP inducer
b. CYP inhibitor
a. CYP inducer
187
rifampin
a. CYP inducer
b. CYP inhibitor
a. CYP inducer
188
carbamazepine
a. CYP inducer
b. CYP inhibitor
a. CYP inducer
. This
results in increased biotransformation of drugs and can lead
to significant decreases in plasma concentrations of drugs
metabolized by these CYP isozymes
189
erythromycin
a. CYP inducer
b. CYP inhibitor
b. CYP inhibitor
190
ketoconazole
a. CYP inducer
b. CYP inhibitor
b. CYP inhibitor
191
ritonavir
a. CYP inducer
b. CYP inhibitor
b. CYP inhibitor
: Inhibition of drug metabolism can lead to
significant increases in plasma drug concentration and resultant adverse effects or drug toxicity.
192
what phase 1 reaction not involving the P450 system does this drug involve: catecholamine
a. amine oxidation
b. alcohol dehydrogenation
c. esterases
d. hydrolysis
a. amine oxidation
193
what phase 1 reaction not involving the P450 system does this drug involve: histamine
a. amine oxidation
b. alcohol dehydrogenation
c. esterases
d. hydrolysis
a. amine oxidation
194
what phase 1 reaction not involving the P450 system does this drug involve: ethanol
a. amine oxidation
b. alcohol dehydrogenation
c. esterases
d. hydrolysis
b. alcohol dehydrogenation
195
what phase 1 reaction not involving the P450 system does this drug involve: aspirin
a. amine oxidation
b. alcohol dehydrogenation
c. esterases
d. hydrolysis
c. esterases
196
what phase 1 reaction not involving the P450 system does this drug involve: procaine
a. amine oxidation
b. alcohol dehydrogenation
c. esterases
d. hydrolysis
d. hyrolysis
197
what is the most common and the most important conjugation reaction
a. glucuronidation
b. sulfation
a. glucuronidation
[Note: Drugs already
possessing an -OH, -NH2 , or -COOH group may enter phase II
directly and become conjugated without prior phase I metabolism
(Figure 1.16}.] The highly polar drug conjugates are then excreted
by the kidney or in bile.
198
A drug passes through several processes in the kidney before elimination. what are these parts
glomerular filtration
active tubular secreation
passive reabsorption
199
what is the normal glomerular filtration rate
120mL/min/1.73m3
200
Lipid solubility and pH do
influence the passage of drugs into the glomerular filtrate
a. true
b. false
b. false
. Lipid solubility and pH do not
influence the passage of drugs into the glomerular filtrate. variations in GFR and protein binding of drugs do affect this process
201
Secretion primarily occurs in the proximal tubules by two energy-requiring active transport system
one
for anions (for example, deprotonated forms of weak acids} and one
for cations (for example, protonated forms of weak bases}.
glomerular filtrate leave the glomeruli through efferent arterioles
. [Note: Premature infants
and neonates have an incompletely developed tubular secretory
mechanism and, thus, may retain certain drugs in the blood.]
202
may diffuse out of the nephric lumen, back into the systemic circulation
a. charged drug
b. uncharged drug
b. uncharged drug
203
weak acids can be eliminated by alkalinization of
the urine, whereas elimination of weak bases may be increased
by acidification of the urine. This process is called
ion trapping
204
a patient presenting with phenobarbital (weak acid) overdose can be given with this drug to alkalinize the urine and keeps the drug ionized,thereby decreasing its reabsoprtion
a. HCl
b. bicarbonate
b. bicarbonate
205
where does desulfiram drug be eliminated
a. via intestine
b. via bile
c. lungs
c. lungs
206
is the sum of all clearances from the drug-metabolizing and drug-eliminating organs
a. total body (systemic ) clearance
b. half life
a. total body (systemic) clearance
207
is often the major organ of excretion
a. intesitine
b. kidney
c. liver
b. kidney
208
what is the formula of clearance
CLtotal = CLhepatic + CLrenal + CLpulmonary + CLother
209
When a patient has an abnormality that alters the half-life of a drug,
adjustment in dosage is required.
drug inhibits metabolism may require a decrease in dosage .
decreased protein binding, or increased metabolism. This may necessitate higher doses or
more frequent dosing interval
210
what are the common substrate of CYP2C9
celecoxib
glimepiride
ibuprofen
phenytoin
warfarin
211
what are the inducers of CYP2C9
carbamazepine
phenobarbital
rifampin
212
what are the common substrates in CYP2D6
fluoxetine
haloperidol
paroxetine
propranolol
213
what are the common substrates in CYP3A4
carbamazepine
cyclosporine
erythromycin
nifedipine
simvastatine
verapamil
214
what are the inducers of CYP3A4/5
carbamazepine
dexamethasone
phenobarbital
phenytoin
rifampin
215
what is the isozyme of this substrate
celecoxib
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
a.
216
what is the isozyme of this substrate
glimepiride
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
a
217
what is the isozyme of this substrate
ibuprofen
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
a
218
what is the isozyme of this substrate
phenytoin
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
a
219
what is the isozyme of this substrate
warfarin
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
a
220
what is the isozyme of this substrate
fluoxetine
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
b
221
what is the isozyme of this substrate
Haloperidol
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
b
222
what is the isozyme of this substrate
Paroxetine
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
b
223
what is the isozyme of this substrate
Propranolol
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
b
224
what is the isozyme of this substrate
Carbamazepine
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
c
225
what is the isozyme of this substrate
cyclosporine
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
c
226
what is the isozyme of this substrate
Erythromycin
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
c
227
what is the isozyme of this substrate
Nifedipine
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
c
228
what is the isozyme of this substrate
simvastatin
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
c
229
what is the isozyme of this substrate
verapamil
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
c
230
carbamazepine
this is an inducer of what isoenzyme
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
a and c
231
phenobarbital
this is an inducer of what isoenzyme
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
a and c
232
rifampin
this is an inducer of what isoenzyme
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
a and c
233
dexamethasone
this is an inducer of what isoenzyme
a. CYP2C9
b. CYP2D6
c. CYP3A4/5
c
234
is reached
when the rate of drug elimination is equal to the rate of drug administration,
such that plasma and tissue levels remain relatively constant.
a. volume of distribution
b. steady state concentration
b. steady state concentration
235
The sole determinant of the rate that a drug achieves steady
state is the
a. volume of distribution
b. half-life
b. half life
236
Note: A faster rate of
infusion does not change
the time needed to achieve
steady state. Only the
steady-state concentration
changes.
237
. That is, the
"rate in" equals the "rate out" As in the case for IV infusion,
90% of the steady-state value is achieved in
a. t1/2
b.2t1/2
c. 3.3t1/2
c. 3.3t1/2
238
Drugs are generally administered to maintain
a Cas within the therapeutic window. It takes 4 to 5 half-lives for a
drug to achieve Css
a. maintenance dose
b. loading dose
a. maintenance dose
239
rapid obtainment of desired plasma
levels is needed (for example, in serious infections or arrhythmias).
a. maintenance dose
b. loading dose
b. loading dose
Disadvantages of loading doses include increased risk of drug toxicity and a longer time for the plasma concentration to fall if excess
levels occur.
240
1.1 An 18-year-old female patient is brought to the emergency department due to drug overdose. Which of the
following routes of administration is the most desirable
for administering the antidote for the drug overdose?
A. Intramuscular
B. Intravenous
C. Oral
D. Subcutaneous
E. Transdermal
Correct answer = B. The intravenous route of administration
is the most desirable because it results in achievement of
therapeutic plasma levels of the antidote rapidly.
241
1.2 Drug A is a weakly basic drug with a pi<,. of 7.8. If administered orally, at which of the following sites of absorption will the drug be able to readily pass through the
membrane?
A. Mouth (pH approximately 7.0)
B. Stomach (pH of 2.5)
C. Duodenum (pH approximately 6.1)
D. Jejunum (pH approximately 8.0)
E. Ileum (pH approximately 7.0)
Correct answer= D. Because Drug A is a weakly basic drug
(pK, = 7.8), it will be predominantly in the nonionized form
in the jejunum (pH of 8.0). For weak bases, the nonionized
form will permeate through the cell membrane readily.
242
1.3 KR2250 is an investigational cholesterol-lowering
agent. KR2250 has a high molecular weight and is
extensively bound to albumin. KR2250 will have a(n)
______ apparent volume of distribution (Vd)·
A. High
B. Low
C. Extremely high
D. Normal
correct answer = B. Because of its high molecular weight
and high protein binding, KR2250 will be effectively trapped
within the plasma (vascular) compartment and will have a
low apparent volume of distribution.
243
1.4 A 40-year-old male patient (70 kg) was recently diagnosed with infection invoMng methicillin-resistant
S. aureus. He received 2000 mg of vancomycin as an IV
loading dose. The peak plasma concentration of vancomycin was 28.5 mg/L. The apparent volume of distribution is:
A. 1 LJkg
B. 7 LJkg
c. 10 LJkg
D. 14 LJkg
E. 70 LJkg
Correct answer = A. V d = dose/C = 2000 mg/28.5 mg/L
= 70.1 L. Because the patient is 70 kg, the apparent
volume of distribution In L..lkg will be approximately 1 Ukg
(70.1 U70 kg).
244
1.5 A 55-year-old woman is brought to the emergency
department because of seizures. She has a history of
renal disease and currently undergoes dialysis. She
receives an intravenous infusion of antiseizure Drug X.
Which of the following is likely to be observed with use of
Drug X in this patient?
a. half life : INCREASE
dosage : INCREASE
b. half life: DECREASE
dosage : DECREASE
c. half life: INCREASE
dosage: MIDDLE
d. half life: INCREASE
dosage: DECREASE
e. half life: MIDDLE
dosage: MIDDLE
Correct answer = D. Because the patient has a renal disorder, she may not be able to excrete the drug effectively.
Therefore, the half-life of Drug X will be prolonged. As the
half-life Is prolonged, the dosage must be reduced so the
patient will not have serious toxic effects of Drug X.
245
1.6 A 68-year-old woman is brought to the emergency
department for treatment of a myocardial infarction. She
is currently taking clopidogrel (antiplatelet agent) and
aspirin daily, as well as omeprazole (potent CYP inhibitor) for heartburn. Which of the following is the most likely
contributor to her myocardial infarction today?
A. Reduced antiplatelet activity of clopidogrel due to
aspirin
B. Reduced antiplatelet activity of clopidogrel due to
omeprazole
c. Hypersensitivity reaction due to clopidogrel
D. Increased antiplatelet activity of clopidogrel due to
omeprazole
E. Increased antiplatelet activity of clopidogrel due to
aspirin
Correct answer = B. Clopidogrel is a prodrug and requires
CYP2C19 activity for conversion to an active metabolite.
Because omeprazole is a potent CYP inhibitor, clopidogrel
Is not converted to the active metabolite, and therefore the
antlplatelet activity Is reduced, potentially contributing to
myocardial Infarction.
246
1.7 Which of the following reactions represents Phase II of
drug metabolism?
A. Amidation
B. Hydrolysis
C. Oxidation
D. Reduction
E. Sulfation
Correct answer = E. Phase II metabolic reactions Involve
conjugation reactions to make phase I metabolites more
polar. Sulfation and glucuronidation are the most common
phase II conjugation reactions.
247
1.8 A pharmacokinetic study of a new antihypertensive
drug is being conducted in healthy human volunteers.
The half-life of the drug after administration by continuous intravenous infusion is 12 hours. Which of the following best approximates the time for the drug to reach
steady state?
A. 24 hours
B. 48 hours
C. 72 hours
D. 120 hours
E. 240 hours
Correct answer = B. A drug will reach steady state in about
4 to 5 half-lives. Therefore, for this drug with a half-life of
12 hours, the approximate time to reach steady state will
be 48 hours.
248
1.9 A 64-year-old female patient (60 kg) is treated with
experimental Drug A for type 2 diabetes. Drug A is
available as tablets with an oral bioavailability of 90%.
If the vd is 2 L1kg and the desired steady-state plasma
concentration is 3.0 mg/L, which of the following is the
most appropriate oral loading dose of Drug A?
A. 6mg
B. 6.66mg
C. 108 mg
D. 360 mg
E. 400 mg
Correct answer= E. For oral dosing, loading dose= [(Vd)
x {desired steady-state plasma concentration)/F]. The Vd
In this case Is corrected to the patient's weight Is 120 L.
The F value Is 0.9 (because bloavallablllty Is 90%, that Is,
90/100 = 0.9). Thus, loading dose= (120 L x 3.0 mg/L)/0.9
=400 mg.
249
1.10 A 74-year-old man was admitted to the hospital for treatment of heart failure. He received 160 meg of digoxin
intravenously, and the plasma digoxin level was 0.4 ng/
mL. If the desired plasma concentration of digoxin for
optimal therapeutic activity in heart failure is 1.2 nglml,
and the patient has an estimated V d of 400 L, calculate
the additional dose of digoxin needed for this patient to
achieve the desired plasma concentration.
A. 128 meg
B. 160 meg
C. 320 meg
D. 480 meg
E. 640 meg
ment of heart failure. He received 160 meg of digoxin
intravenously, and the plasma digoxin level was 0.4 ng/
mL. If the desired plasma concentration of digoxin for
optimal therapeutic activity in heart failure is 1.2 nglml,
and the patient has an estimated V d of 400 L, calculate
the additional dose of digoxin needed for this patient to
achieve the desired plasma concentration.
A. 128 meg
B. 160 meg
C. 320 meg
D. 480 meg
E. 640 meg
1. Pharmacokinetics
Correct answer = B. A drug will reach steady state in about
4 to 5 half-lives. Therefore, for this drug with a half-life of
12 hours, the approximate time to reach steady state will
be 48 hours.
Correct answer= E. For oral dosing, loading dose= [(Vd)
x {desired steady-state plasma concentration)/F]. The Vd
In this case Is corrected to the patient's weight Is 120 L.
The F value Is 0.9 (because bloavallablllty Is 90%, that Is,
90/100 = 0.9). Thus, loading dose= (120 L x 3.0 mg/L)/0.9
=400 mg.
Correct answer = C. The additional dosage of digoxin
needed to achieve the desired plasma concentration can
be calculated using the equation Vd (C2 - C1). C1 is the current plasma concentration (0.4 nglml) and ~ is the desired
plasma concentration (1.2 ng/ml). Therefore, the addtional
dosage of digoxin is [400 L x (1.2- 0.4) nglml)] = 320 meg.
