3) Pharmacokinetics/Dosing Schedule

Question 1

Major processes involved in pharmacokinetics

Answer 1

• Absorption
• Distribution
• Metabolism
• WElimination

Question 2

Apparent volume of distribution (Vd)

Answer 2

• The theoretical volume that would be necessary to contain the total amount of an administered drug at the same concentration that it is observed in the blood plasma

Question 3

Volume of distribution (Vd) is an important indicator of

Answer 3

• The extent of drug distribution into body fluids and tissues

Question 4

A large volume of distribution usually indicates

Answer 4

• The drug distributes extensively into body tissues and fluids

Question 5

Clearance (Cl)

Answer 5

• The ratio of the rate of elimination of a drug to the concentration of the drug in the plasma or blood

Question 6

Biodisposition

Answer 6

• The processes of drug absorption, distribution, and elimination

Question 7

Effective drug concentration

Answer 7

• The concentration of a drug at the receptor site

Question 8

Half life t1/2

Answer 8

• The time required for the amount of drug in the body or blood to fall by 50% of its Cmax

Question 9

Area under the curve (AUC)

Answer 9

• The graphic area under a plot of drug concentration versus time after a single dose or during a single dosing interval

Question 10

Bioavailability (F)

Answer 10

• The fraction (or percentage) of the administered dose of drug that reaches the systemic circulation
• Defined as unity (or 100%) in the case of intravenous administration

Question 11

Drug extraction

Answer 11

• The extraction of drug from the circulation by the liver is equal to blood flow (Q) times the difference between entering and leaving drug concentration, ie, Q × (Ci – Co).

Question 12

Therapeutic window

Answer 12

• The safe range between the minimum therapeutic concentration (determines the trough) and the minimum toxic concentration of a drug (determines the peak)

Question 13

Dose regimen

Answer 13

• Plan for drug administration over a period of time

Question 14

To maintain the plasma concentration within a specified range over long periods of therapy

Answer 14

• A schedule of maintenance doses is used
• If it is necessary to achieve the target plasma level rapidly, a loading dose may be used to “load” the Vd with the drug

Question 15

Maintenance dosage

Answer 15

• Dose required for regular administration to maintain a target plasma level
• Dosing rate = (CL x desired plasma concentration)/bioavailability

Question 16

Loading dose

Answer 16

• Dose required to achieve a specific plasma drug concentration level (Cp) with a single administration
• Loading dose = (Vd x desired plasma concentration)/bioavailability