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Pharmacokinetics > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

How long does it take to prepare a drug

A

approx 17 years

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2
Q

What is Pharmacokinetics?

A

β€œPharmacokinetics is what body does to the drug”

It Include events starting from drug administration to the elimination

Deals with dose, dosing frequency, route, drug concentration in the body, absorption, distribution, metabolism and excretion

All of these four criteria influence the levels of drug exposure to tissues and thus influence the performance and pharmacologic activity of the drug

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3
Q

What is Pharmacodynamics ?

A

Pharmacodynamic is what drug does to our body

It is also the extent of absorption, distribution and elimination

Comprises is the science that describes the relationship between the drug concentration at the receptor and biological activity (i.e., pharmacologic response or drug effect)

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4
Q

When a number is expressed in exponential notation it takes the following form:

A

number = base exponent

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5
Q

What will be π‘’βˆ’βˆž

A

0

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6
Q

➒ Calculus is used to

A

monitor drug movement in the body

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7
Q

In the body, drugs remain at

A

a moving or dynamic state

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8
Q

Biopharmaceutics is the

A

Studies the influence of physicochemical properties of drugs, dosage forms and physiological factors affecting plasma
concentration through absorption and distribution

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9
Q

What will be 𝑒0?

A

1

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10
Q

What will be π‘’βˆ’1?

A

0.368

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11
Q

Disposition is the

A

Events that occur after drug absorption
it Encompasses distribution and elimination phases
This term is used interchangeably with the term β€˜pharmacokinetics’

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12
Q

Pharmacokinetics (PK) and pharmacodynamics (PD) relate

A

input with the output or input with the response

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13
Q

Differential equations

A

Quantitate drug concentration in the body over time

dc/dt

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14
Q

Integral equations

A

Model cumulative responses (therapeutic or toxic) of drugs in the body
C=12-2t or y=b-mx

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15
Q

In Semi log Graph Cycles

A

Each cycle is a 10-fold increase in numbers or a single log10 unit
Ex 0.1 10 100

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16
Q

The straight-line showing a relation between two variables is called a

A

regression line

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17
Q

In Pharmacokinetics Elimination is _________ and tissue concentration is __________.

A

Irreversible , Reversible

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18
Q

Absorption is

A

From the site of administration, the drug enters the neighboring blood
vessels and then enters the systemic circulation, a process called drug
absorption

An oral tablet first dissolves in the GIT, where released drug traverses the
GI and enters the GI blood capillaries

After entering the GI capillaries, drug moves into the liver via the portal
vein where it may get altered before entering the systemic circulation

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19
Q

Distribution is

A

From the systemic circulation, the drug reaches various tissues and organs, a process called drug distribution

Drug distribution is a reversible process

Drugs entering the tissues should return to the blood for elimination

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20
Q

Elimination is

A

After a certain time, the body gets rid of the drug by making it elimination friendly by breaking it into pieces, making it water-loving, and directing it to the elimination organ, a process called drug elimination

The common route of elimination is the kidney; drugs that enter or distribute in the liver are converted to metabolites for later excretion into the bile

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21
Q

Pharmacodynamics It is change in the receptor ____ and ______

A

amount, Density

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22
Q

An oral tablet has to circumvent several roadblocks

A

during its journey from the GIT to the liver and finally to the general circulation

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23
Q

Situations that reduce the amount of the intact drugs in the blood are

A

Incomplete dissolution

Metabolism in the gut lumen or by enzymes in the gut wall

Metabolism in the liver

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24
Q

The drug loss before its entry into the systemic circulation is called

A

first-pass loss

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25
This recycling of drugs back to the liver is called the
entero-hepatic cycle
26
Urine, Blood Plasma, and Saliva are
good tools for measuring concentrations
27
Plasma concentration reflects the drug concentration at the site of action and
The relationship is often linear in nature An increase/decrease in plasma concentration will be reflected by a proportional increase/decrease at the site of action
28
Minimum effective concentration (MEC)
Minimal level of drug in the blood in order to produce an effect
29
Minimum toxic concentrations (MTC)
Minimal level of drug in the blood that produces a toxic effect It also tells us inter/intrapatient variability
30
Therapeutic range/window
The range between MEC and MTC and that is the difference we need to monitor
31
Pharmacokinetic variability occurs due to variations in drug clearance which include
The dose of drugs is determined assuming normal functioning of major metabolizing and excretion organs Under normal circumstances, the dose of a drug does not change from person to person Reduced clearance of a drug may result in drug accumulation and adverse effects Faster clearance may render the drug ineffective
32
To circumvent the pharmacokinetic variability, drug therapies are monitored by measuring
plasma-drug-concentration and drug-clearance
33
Pharmacodynamic variability may also occur among patients
The plasma concentration of a drug may be the same in two different patients, but the therapeutic response produced may be different Same plasma concentration but different therapeutic effects
34
The Site to monitor drug concentration are
Plasma and serum are the most frequently used biological fluids Urine and saliva are also used, but less frequently
35
Limitations of plasma-concentration monitoring
Lack of a clear relation between the plasma concentration and therapeutic effect Some drugs have a wide therapeutic window which makes monitoring of plasma concentration is unnecessary
36
Models are frequently used to simplify the _______ and determine or predict the drug behavior in the body
body process
37
Models predict the kinetic behavior of drugs under different conditions
Changing the dose/formulation In presence of different drugs In presence of various diseases states After administration through various routes
38
A ________ is an imaginary unit or territory consisting of a group of tissues with similar rates of drug uptake
compartment
39
Based on drug uptake, tissues fall into three major groups:
Highly-perfused tissues: Drug uptake is extremely rapid Moderately-perfused tissues: Drug uptake is slower than highly perfused tissues Poorly-perfused tissues: Drug uptake is extremely slow
40
Pharmacokinetics of most drugs can be modeled into two compartments
One compartment | Two-compartment
41
Most Drugs used _______ Compartment Model
One compartment
42
One Compartment Model
The drug is added to and eliminated from a central compartment The central compartment represents plasma and highly perfused tissues that instantaneously equilibrate with drug In the case of intravenous administration, the drug directly enters the central compartment The drug is eliminated from the central compartment because elimination organs, kidney, and liver, are well-perfused tissues
43
Two Compartment Model
Drug moves to and from the central compartment to the peripheral and from the tissue compartment The tissue compartment does not consist of a specific tissue, but the total drug amount represents the drug present in all tissues The total drug in the body equals the sum of the drug in the central plus in the tissue compartment The amount of drug that remained in and eliminated from the body at any time can be calculated using either the one-compartment or two-compartment pharmacokinetic parameters
44
Physiological models take real physiological factors into account to predict drug kinetics which includes
Blood flow rate The extent of plasma protein binding Metabolism by liver
45
Plasma concentration (dependent variable) at a given time depends on
β–ͺ Dose administered (usually constant) β–ͺ Sampling time (independent variable) β–ͺ Plasma concentration = f (dose, time) β–ͺ This equation explains how absorption, distribution and elimination influence plasma-concentration-time profiles
46
Most drugs follow ______ order and only 5% follow ______ order
First , Zero
47
In first-order kinetics, the _______________________ with a proportionality constant called first-order rate constant (k)
rate of the process is proportional to the amount or concentration of the drug
48
k0 = zero-order rate constant, whose unit is
mass/time
49
One-Compartment Linear Model includes
Rapid mixing Rapid equilibrium First order (linear) elimination Constant volume system
50
Drug-concentration in the compartment represents
the plasma concentration
51
Drug-amount in the compartment represents the
drug amount in the body
52
Application of One Compartment Model include
Predict plasma concentration Estimate the duration of action Determine the dose to produce an intended plasma concentration Intravenous loading dose used to achieve a particular plasma concentration
53
Application Of Half-life
Drug residence time Frequency of drug administration Time to reach steady-state concentration
54
Clearance (Cl) include
A measure of the elimination efficiency of the body to rid drug of the body Also defined as the volume of plasma or blood cleared of drug per unit of time (units: volume/time) Clearance influences the average plasma concentration of drugs after multiple dosing or after constant IV infusion Used to estimate the maintenance dose to design therapeutic regimens (IV infusion or multiple dosing)
55
Clearance is expressed in three forms:
1. Amount per unit time (mg/min) 2. Volume per unit time (mL/min) 3. Fraction-dose per unit time (Fraction/min)
56
Two major processes of drug elimination are
Renal excretion Metabolism (primarily liver)
57
Kidney in conjunction with liver eliminates over
90% of drugs
58
Renal elimination
Drug moves or is excreted from the blood to the renal tubule and then eliminated in the urine
59
Metabolism
Parent drug is converted to one or more molecular entities, called, metabolites, via enzymatic action
60
Drug elimination rate is composed of two major components
β–ͺ Urinary excretion rate-constant (π‘˜π‘Ÿ) β–ͺ Metabolic rate-constant (π‘˜π‘š) π‘˜ = π‘˜π‘Ÿ + π‘˜m
61
The term β€˜non-renal rate (π‘˜π‘›π‘Ÿ)’ include all possible elimination pathways, although π‘˜π‘›π‘Ÿ equals to π‘˜π‘š under normal circumstances β–ͺ
k can be written as π‘˜ = π‘˜π‘Ÿ + π‘˜π‘›r
62
Urinary excretion rate cannot be determined at a particular time because
the urine is collected over a time interval (e.g., from 0-2 h…)
63
Renal clearance
measures the efficiency of the kidneys in excreting the drug
64
Advantages of the Cumulative Method are
Deals with real the time-points (no π‘‘π‘šπ‘–π‘‘) Incomplete bladder emptying does not impact the outcome much Avoid frequent sampling when you want to estimate π΄π‘’βˆž
65
Disadvantages of the Cumulative Method are
Sampling should be for at least 4 half-lives in order to estimate π΄π‘’βˆž (a problem for drugs with long-half life drugs) π΄π‘’βˆž cannot be estimated in case of accidental sample loss
66
Advantages of Urinary Excretion Rate Method
Sample loss does not impact the outcome One misplaced sample eliminate one data point, but the existing data points are still useful Sample collection for β‰₯ 4 half-lives is not required
67
Disadvantages of Urinary Excretion Rate Method
Use of π‘‘π‘šπ‘–π‘‘ instead of sampling time Shorter interval to relate rate to π‘‘π‘šπ‘–π‘‘ Incomplete bladder emptying affect each data point
68
. What kinetic or dosing factors affect the AUC?
AUC is directly dependent on the input (dose) and inversely related to the output/elimination (clearance): AUC = Dose /Cl

Pharmacokinetics (1 decks)

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