Pharmacokinetics One and Two

Question 1

What are the basic pharmacokinetics perameters?

Answer 1

Bioavailibility
Volume of distribution
- Loading Dose
Plasma Clearance
- Maintanence dose
Half life
-accumulation

Question 2

What is pharmacokinetics?

Answer 2

The study of ADME on a quantitative basis

-How drug concentrations change with time from administration

Question 3

What is the true definition of pharmacokinetics?

Answer 3

Pharmacokinetics is the study of drug concentrations time profile in the body

Question 4

What is the basic time course of a drug?

Answer 4

Absorption
Distribution
(metabolism or) Excretion

Question 5

What is drug absorption?

Answer 5

Process by which the unchanged drug moves from the site of administration into systemic circulation

Question 6

What is drug absorption relevant for?

Answer 6

Non-vascular administration (not-intravenous (IV))

• Oral (po)
• Subcutaneous (sc)
• Intramuscular (im)
• Rectal (pr)
• (sublingual)

Question 7

What is bioavailibility?

Answer 7

The fraction of unchanged drug that reaches systemic circulation (out of dose administered- some may break down or be excreted-known as first phase effect)

Question 8

What is the equation for bioavailibility?

Answer 8

F = AUCpo x DOSEiv
AUCIV DOSEpo

AUC = Area under plasma concentration curve vs time

F is constant, so you can change the doseage and to change the AUC, but F will always be the same

Question 9

What is the first phase effect?

Answer 9

Loss of drug occurring before the drug reaches systemic circulation

Question 10

What are the three pharmacokinetic parameters?

Answer 10

Volume of distribution
Plasma Clearance (cl)
Plasma half life (T0.5)

Question 11

What is distribution?

Answer 11

Processes involved in delivery of the drug to the tissues via the arterial blood. (general circulation to tissue)

Question 12

What defines distribution?

Answer 12

The parameter known as volume of distribution

Question 13

What is the equation for the volume of distribution?

Answer 13

V = Amount of drug in the body

Plasma drug concentration

Question 14

What are the determinants for the volume of distribution?

Answer 14

Blood Flow
Body mass and composition
Physicochemico properties of the drug
Tissue binding
Drug binding to plasma proteins (decreases v)

Question 15

What is the loading dose?

Answer 15

The first dose a drug treatment, required to reach the target concentration RAPIDLY

Question 16

What is the equation of LD(mg)?

Answer 16

LD = V(L) x target concentration (mg/L)

Two factors must be known

Question 17

What is drug elimination?

Answer 17

The irreversible removal of drug from the body

Question 18

What process can occur to cause drug elimination?

Answer 18

Drug metabolism (conversion of drug into another chemical species)
Drug excretion (loss of drug in bile or urine)

Question 19

What is the definition of clearance?

Answer 19

Volume of plasma drug cleared per a unit time (L/h)

Question 20

What is the equation for elimination rate?

Answer 20

CL x concentration = elimination rate

Question 21

What is the equation for clearance?

Answer 21

Cl= Dose / AUC

Question 22

What is the definition of maintenance dose(MD)?

Answer 22

Dose rate to achieve and maintain a target concentration

Question 23

What is steady state?

Answer 23

When dose rate in= rate of elimination

Question 24

What is the equation for MD?

Answer 24

MD (mg/h) = CL (l/h) x Target concentration (mg/L)

Question 25

What is half life?

Answer 25

The time required for drug concentration to halve

Question 26

What does half life depend on?

Answer 26

Volume and clearance

Question 27

Is half life variable?

Answer 27

Usually constant irrespective of drug concentration

Question 28

What is the concentration of drug in the body related to?

Answer 28

The number of half lives that have occured since the time of administration

Question 29

If the half life is known then what is it possible to calculate?

Answer 29

How much drug is left in the body | How long it will take to reach steady state

Question 30

What is the equation for half life?

Answer 30

T0.5 = 0.7 V/Cl

Question 31

after four half lifes how much drug will have been eliminated?

Answer 31

more than 90%

Question 32

What does half lives help predict?

Answer 32

When the therapeutic or toxic drug effect is likely to cease

Question 33

How many half lives is considered the point where a negligible amount of drug remains in the system?

Answer 33

Four half lives

Question 34

What is accumulation?

Answer 34

When after repeated dosing or infusion, the drug will accumulate in the body until input rate= elimination rate (steady state)

Question 35

When does steady state occur?

Answer 35

Drug accumulation is complete(no longer occurring) and concentrations have plateaued (low level of drug)

Question 36

How many half lives does it usually take to reach steady state?

Answer 36

Four

Question 37

What is the time course of drug concentration determined by? (reset me)

Answer 37

Bioavailibility (F) Distribution (V) Clearance (CL)