Toxicokinetics Flashcards
Regarding the 2-compartment model of classic toxicokinetics, which of the following is true?
a. There is rapid equilibration of chemical between central and peripheral compartments
b. The logarithm of plasma concentration vs time data yields a linear relationship
c. There is more than one dispositional phase
d. It is assumed that the concentration of a chemical is the same throughout the body
e. It is ineffective in determining effective doses in toxicity studies
c. There is more than one dispositional phase
When calculating the fraction of a dose remaining in the body over time, which of the following factors need not be taken into consideration?
a. half-life
b. initial concentration
c. time
d. present concentration
e. elimination rate constant
a. half-life
All of the following statements regarding apparent volume of distribution (Vd ) are true EXCEPT:
a. Vd relates the total amount of chemical in the body to the concentration of chemical in the plasma
b. Vd is the apparent space into which an amount of chemical is distributed in the body to result in a given plasma concentration.
c. A chemical that usually remains in the plasma has a low Vd
d. Vd will be low for a chemical with high affinity for tissues
e. Vd can be used to estimate the amount of chemical in the body if the plasma concentration is known.
d. Vd will be low for a chemical with high affinity for tissues
Chemical clearance:
a. is independent of Vd
b. is unaffected by kidney failure
c. in indirectly proportional to Vd
d. is performed by multiple organs
e. is not appreciable in the GI tract
d. is performed by multiple organs
A chemical with which of the following half-lives (T1/2) will remain in the body for the longest period time when given equal dosage of each?
a. T1/2= 30 minutes
b. T1/2 = 1 day
c. T1/2 = 7 hours
d. T1/2= 120s
e. T1/2= 1 month
e. T1/2= 1 month
With respect to first-order elimination, which of the following statements is FALSE?
a. The rate of elimination is directly proportional to the amount of chemical in the body
b. a semilogarithmic plot of plasma concentration versus time shows a linear relationship.
c. Half-life (T1/2) differs depending on the dose.
d. Clearance is dosage independent.
e. The plasma concentration and tissue concentration decrease similarly with respect to the elimination rate constant.
c. Half-life (T1/2) differs depending on the dose.
The toxicity of a chemical is dependent on the amount of chemical reaching the systemic circulation. Which of the following does NOT greatly influence systemic availability?
a. absorption after oral dosing
b. intestinal motility
c. hepatic first-pass effect.
d. intestinal first-pass effect
e. incorporation into micelles.
b. intestinal motility
Which of the following is NOT and advantage of a physiologically based toxicokinetic model?
a. Complex dosing regimens are easily accommodated.
b. The time course of distribution of chemicals to any organ is obtainable.
c. The effects of changing physiologic parameters on tissue concentrations can be estimated
d. The rate constants are obtained from gathered data
e. The same model can predict toxicokinetics of chemicals across species.
d. The rate constants are obtained from gathered data
Which of the following will not help to increase the flux of a xenobiotic across a biological membrane?
a. decreased size
b. decreased oil:water partition coefficient
c. increased concentration gradient
d. increased surface area
e. decreased membrane thickness
b. decreased oil:water partition coefficient
Which of the following statements is true regarding diffusion-limited compartments?
a. Xenobiotic transport across the cell membrane is limited by the rate at which blood arrives at the tissue.
b. Diffusion-limited compartments are also regerred to as flow-limited compartments
c. Increased membrane thickness can cause diffusion-limited xenobiotic uptake.
d. Equilibrium between the extracellular and intracellular space is maintained by rapid exchange between the two compartments
e. Diffusion of gases across the alveolar septa of a healthy lung is diffusion-limited.
c. Increased membrane thickness can cause diffusion-limited xenobiotic uptake.
