PK Module 2: Basic PK

Which of the following would result in a drug having a HIGH clearance?

• High extraction ratio + High blood flow

• High extraction ratio + Low blood flow

• Low extraction ratio + High blood flow

• Low extraction ratio + Low blood flow

Answer explanation

Clearance is dependent upon both the drug extraction ratio (E, organ's ability to remove drug) and the blood flow (Q) to the organ.  Recall that HIGH clearance is only achieved when both E and Q are high.

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Pharmacokinetics

Lesson 2

A doctor is trying to determine the clearance rate of a new drug. Which of the following would be the correct units for clearance?

• Concentration of the drug per half-life.

• Dose of the drug per volume of blood.

• Half-life of the drug per dose given.

• Volume of blood cleared of the drug per unit of time.

• Half-life of the drug per volume of blood.

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Pharmacokinetics

Lesson 2

A doctor is trying to determine the clearance rate of a new drug. Which of the following would be the correct units for clearance?

• Concentration of the drug per half-life.

• Dose of the drug per volume of blood.

• Half-life of the drug per dose given.

• Volume of blood cleared of the drug per unit of time.

• Half-life of the drug per volume of blood.

Answer explanation

V = X/Co

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Pharmacokinetics

Lesson 2

If for a drug there is extensive binding to plasma proteins, but not within or to blood cells, would you expect the concentration of a drug in whole blood or plasma to be greater, or are they about the same? The unbound drug concentration is the same in plasma water and cellular fluids.

• whole blood

• plasma

• about the same

Answer explanation

The concentrations in the blood and plasma will be the same if the drug does not bind to plasma proteins or is not concentrated in blood cells.

If the drugs have extensive protein binding with no extensive concentration in blood cells, the concentration will be higher in the plasma.

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Pharmacokinetics

Lesson 2

If for a drug there is extensive binding to blood cell components, but no binding to plasma proteins, would you expect the concentration of a drug in whole blood or plasma to be greater, or are they about the same? The unbound drug concentration is the same in plasma water and cellular fluids.

• whole blood

• plasma

• about the same

Answer explanation

The concentrations in the blood and plasma will be the same if the drug does not bind to plasma proteins or is not concentrated in blood cells.

If the drugs have extensive concentration in blood cells, the concentration will be higher in the blood.

Tags

Pharmacokinetics

Lesson 2

If for a drug there is no binding to plasma proteins or blood cell components, would you expect the concentration of a drug in whole blood or plasma to be greater, or are they about the same? The unbound drug concentration is the same in plasma water and cellular fluids.

• whole blood

• plasma

• about the same

Answer explanation

The concentrations in the blood and plasma will be the same if the drug does not bind to plasma proteins or is not concentrated in blood cells.

Tags

Pharmacokinetics

Lesson 2

Consider a patient taking a medication that follows first-order elimination. The amount of medication eliminated from the patient's body per unit time:

• remains constant while the fraction of medication eliminated decreases as the amount of drug in the body decreases.

• decreases while the fraction of medication eliminated remains constant as the amount of drug in the body decreases.

• remains constant while the fraction of medication eliminated also remains constant as the amount of drug in the body decreases.

• increases while the fraction of medication eliminated remains constant as the amount of drug in the body decreases.

• is independent of the amount of drug in the body.

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Pharmacokinetics

Lesson 2

Consider a patient taking a medication that follows zero-order elimination. The amount of medication eliminated from the patient's body per unit time:

• remains constant while the fraction of medication eliminated increases as the amount of drug in the body decreases.

• decreases while the fraction of medication eliminated remains constant as the amount of drug in the body decreases.

• remains constant while the fraction of medication eliminated also remains constant as the amount of drug in the body decreases.

• increases while the fraction of medication eliminated remains constant as the amount of drug in the body decreases.

• is directly proportional to the amount of drug in the body.

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Pharmacokinetics

Lesson 2

Consider a patient taking a medication that follows first-order elimination. The fraction of medication eliminated from the patient's body per unit time:

• remains constant as the amount of drug in the body decreases.

• decreases while the amount of drug in the body decreases.

• remains constant while the amount of medication eliminated also remains constant.

• increases as the amount of drug in the body decreases.

Tags

Pharmacokinetics

Lesson 2

A patient is undergoing a drug treatment. Which of the following parameters would be a measure of the patient's organ's ability to remove the drug?

• Extraction Ratio (E)

• Clearance (Cl)

• Volume of distribution (Vd)

• Elimination rate constant (K)

Tags

Pharmacokinetics

Lesson 2