Pharmacokinetics - Exam 1 Questions With
Correct Answers
Pharmacokinetics (PK) - CORRECT ANSWER✔✔-- the study of the process by | | | | | | | | | | |
which a drug is absorbed, distributed, metabolized, and excreted by the body
| | | | | | | | | | | |
(what the body does to the drug)
| | | | | |
-only free drugs can be distributed into the systemic circulation
| | | | | | | | |
Optimal Drug Therapy - CORRECT ANSWER✔✔--determination of optimal dosage
| | | | | | | | |
regimen (how many mg and how many times a day)
| | | | | | | | |
-to maintain the plasma drug concentration within the therapeutic window
| | | | | | | | |
IV Bolus - CORRECT ANSWER✔✔--rapid injection
| | | | |
-ensures that the entire dose enters the systemic circulation immediately
| | | | | | | | |
-skip absorption and metabolism steps
| | | |
One Compartment Model - CORRECT ANSWER✔✔--body acts like a single
| | | | | | | | | |
homogenous compartment |
-drug rapidly distributes uniformly in it
| | | | |
-drug is in rapid equilibrium between the blood and the tissues
| | | | | | | | | |
-changes in plasma concentration of drug --> proportional changes in tissue drug
| | | | | | | | | | | |
levels
,Problem with One Compartment Model - CORRECT ANSWER✔✔-blood
| | | | | | | |
compartment alone is not enough to explain drug disposition, thus multi-
| | | | | | | | | |
compartment model |
First Order Elimination - CORRECT ANSWER✔✔--the elimination rate is
| | | | | | | | |
proportional to the concentration (or amount) of the drug
| | | | | | | |
-zero order: same amount of drug eliminated over time
| | | | | | | |
-first order: same percentage of drug eliminated over time
| | | | | | | |
Linear Kinetics - CORRECT ANSWER✔✔--for a drug that has linear kinetics, if we
| | | | | | | | | | | | |
double the dose then the plasma concentration will double at each time point
| | | | | | | | | | | |
-pharmacokinetic parameters (clearance and volume of distribution) are constant,
| | | | | | | |
|that is, they are independent of dose
| | | | | |
Nonlinear Kinetics (FYI) - CORRECT ANSWER✔✔--dose-dependent PK
| | | | | |
-it occurs when one (or more) of ADME processes shows saturation
| | | | | | | | | |
-pharmacokinetic parameters (clearance and volume of distribution) are
| | | | | | | |
dependent of dose | |
One Compartment Linear Model: IV Bolus -- Cartesian Plot - CORRECT
| | | | | | | | | | |
ANSWER✔✔-... (nonlinear) |
One Compartment Linear Model: IV Bolus -- Semi-Log Plot - CORRECT
| | | | | | | | | | |
ANSWER✔✔-... (linear) |
Cp=Cpo*e^(-k*t)
, ln(Cp)=ln(Cpo)-k*t - CORRECT ANSWER✔✔-Cp: plasma drug concentration | | | | | |
Cpo: plasma drug concentration at time=0
| | | | |
t: time
|
Kel: elimination rate constant
| | |
PK Parameter: Volume of Distribution (Vd) - CORRECT ANSWER✔✔--Measure of
| | | | | | | | | |
drug distribution in the body (L)
| | | | |
-The size of the space into which the drug uniformly distributes depends on the
| | | | | | | | | | | | | |
physicochemical properties of the drug | | | |
-Drug specific property
| |
-example: lipophilic compounds have better tissue distribution, therefore larger
| | | | | | | | |
Vd
-Determined from the amount of the dose and plasma drug concentration
| | | | | | | | | | |
resulting immediately after the dose is injected
| | | | | |
-Vd = A / Cp
| | | |
-Vd = (amount of drug in the body)/(plasma drug concentration)
| | | | | | | | |
-Immediately after an IV bolis dose, | | | | |
Vd = Dose/Cpo
| |
-The Vd governs the plasma concentration of the drug after a given dose
| | | | | | | | | | | |
-Large Vd leads to lower Cp (when other PK properties are the same)
| | | | | | | | | | | |
-In most cases, Vd dose doesn't correspond to a physiologic volume
| | | | | | | | | |
-specific occasions: if drug is confined to the bloodstream (V=~5L) or total body
| | | | | | | | | | | | |
water (V=~42L), then the PK parameter Vd may reflect the physiologic volume
| | | | | | | | | | |
-With extensive tissue distribution, Vd>100L is common and Vd>10,000L is
| | | | | | | | | |
possible
Correct Answers
Pharmacokinetics (PK) - CORRECT ANSWER✔✔-- the study of the process by | | | | | | | | | | |
which a drug is absorbed, distributed, metabolized, and excreted by the body
| | | | | | | | | | | |
(what the body does to the drug)
| | | | | |
-only free drugs can be distributed into the systemic circulation
| | | | | | | | |
Optimal Drug Therapy - CORRECT ANSWER✔✔--determination of optimal dosage
| | | | | | | | |
regimen (how many mg and how many times a day)
| | | | | | | | |
-to maintain the plasma drug concentration within the therapeutic window
| | | | | | | | |
IV Bolus - CORRECT ANSWER✔✔--rapid injection
| | | | |
-ensures that the entire dose enters the systemic circulation immediately
| | | | | | | | |
-skip absorption and metabolism steps
| | | |
One Compartment Model - CORRECT ANSWER✔✔--body acts like a single
| | | | | | | | | |
homogenous compartment |
-drug rapidly distributes uniformly in it
| | | | |
-drug is in rapid equilibrium between the blood and the tissues
| | | | | | | | | |
-changes in plasma concentration of drug --> proportional changes in tissue drug
| | | | | | | | | | | |
levels
,Problem with One Compartment Model - CORRECT ANSWER✔✔-blood
| | | | | | | |
compartment alone is not enough to explain drug disposition, thus multi-
| | | | | | | | | |
compartment model |
First Order Elimination - CORRECT ANSWER✔✔--the elimination rate is
| | | | | | | | |
proportional to the concentration (or amount) of the drug
| | | | | | | |
-zero order: same amount of drug eliminated over time
| | | | | | | |
-first order: same percentage of drug eliminated over time
| | | | | | | |
Linear Kinetics - CORRECT ANSWER✔✔--for a drug that has linear kinetics, if we
| | | | | | | | | | | | |
double the dose then the plasma concentration will double at each time point
| | | | | | | | | | | |
-pharmacokinetic parameters (clearance and volume of distribution) are constant,
| | | | | | | |
|that is, they are independent of dose
| | | | | |
Nonlinear Kinetics (FYI) - CORRECT ANSWER✔✔--dose-dependent PK
| | | | | |
-it occurs when one (or more) of ADME processes shows saturation
| | | | | | | | | |
-pharmacokinetic parameters (clearance and volume of distribution) are
| | | | | | | |
dependent of dose | |
One Compartment Linear Model: IV Bolus -- Cartesian Plot - CORRECT
| | | | | | | | | | |
ANSWER✔✔-... (nonlinear) |
One Compartment Linear Model: IV Bolus -- Semi-Log Plot - CORRECT
| | | | | | | | | | |
ANSWER✔✔-... (linear) |
Cp=Cpo*e^(-k*t)
, ln(Cp)=ln(Cpo)-k*t - CORRECT ANSWER✔✔-Cp: plasma drug concentration | | | | | |
Cpo: plasma drug concentration at time=0
| | | | |
t: time
|
Kel: elimination rate constant
| | |
PK Parameter: Volume of Distribution (Vd) - CORRECT ANSWER✔✔--Measure of
| | | | | | | | | |
drug distribution in the body (L)
| | | | |
-The size of the space into which the drug uniformly distributes depends on the
| | | | | | | | | | | | | |
physicochemical properties of the drug | | | |
-Drug specific property
| |
-example: lipophilic compounds have better tissue distribution, therefore larger
| | | | | | | | |
Vd
-Determined from the amount of the dose and plasma drug concentration
| | | | | | | | | | |
resulting immediately after the dose is injected
| | | | | |
-Vd = A / Cp
| | | |
-Vd = (amount of drug in the body)/(plasma drug concentration)
| | | | | | | | |
-Immediately after an IV bolis dose, | | | | |
Vd = Dose/Cpo
| |
-The Vd governs the plasma concentration of the drug after a given dose
| | | | | | | | | | | |
-Large Vd leads to lower Cp (when other PK properties are the same)
| | | | | | | | | | | |
-In most cases, Vd dose doesn't correspond to a physiologic volume
| | | | | | | | | |
-specific occasions: if drug is confined to the bloodstream (V=~5L) or total body
| | | | | | | | | | | | |
water (V=~42L), then the PK parameter Vd may reflect the physiologic volume
| | | | | | | | | | |
-With extensive tissue distribution, Vd>100L is common and Vd>10,000L is
| | | | | | | | | |
possible
