Study Guide Chapter 3: Pharmacokinetics

Question 1

What are the pharmacokinetic variables represented by the acronym ADME?

Answer 1

A- Absorption
D- Distribution
M- Metabolism
E- Excretion

Question 2

Name the four ways a drug gets across barriers during absorption.

Answer 2

• Aqueous diffusion
• Lipid diffusion
• Special carriers
• Bulk transport

Question 3

What is aqueous diffusion?

Answer 3

Diffusion via concentration gradient.Drug has to be aqueous and hydrophilic, allowing it to pass through aquaporins

Question 4

What type of drugs typically use lipid diffusion to cross cell membranes?

Answer 4

Small and uncharged or mostly uncharged drugs, such as steroids.

Question 5

What drugs use special carriers in drug absorption?

Answer 5

drugs that are large and charged (utilizing active transport and facilitated diffusion )

Question 6

What is bulk transport?

Answer 6

endocytosis and exocytosis (endocytosis-herceptin, exocytosis-acetylcholine)

Question 7

Define Volume of Distribution (Vd).

Answer 7

*amount of the drug leaving the blood.
*higher Vd indicates more drug leaving the blood.
*Lowed Vd, means the mmore likely it is to stay in the blood.
*Dose=VdxTC

Question 8

What is Clearance (CL)?

Answer 8

Ability of the body to eliminate a drug
* main removal mechanism is in the urine.
*Cl=ROE/C

Question 9

What does concentration (C) refer to in pharmacokinetics?

Answer 9

*measured in ml or L
*the amount of a drug in a given volume

Question 10

What is the Rate of Elimination (ROE)?

Answer 10

How much of the drug is leaving the body per time, measured in mg/min, mg/hr, or ng/min.
ROE= Cl x C

Question 11

What is the difference between first-order and zero-order elimination? And what determines which order a drug uses?

Answer 11

*First-order: clearance is constant, rate of elimination varies with concentration. *Zero-order: rate of elimination is constant, clearance varies.
*the order of elimination depends on how a drug is eliminated from the body

Question 12

What is target concentration?

Answer 12

*The specific amount of drug clinicians aim for, to achieve therapeutic effect

Question 13

And what is Half-life?

Answer 13

*the amount of time it takes to eliminate 1/2 of concentration

Question 14

How do you get to target concentration from Half-life

Answer 14

4(T1/2) = Vd x TC

Question 15

How do find how long it will take to effectively eliminate a drug from the body?

Answer 15

Take half-life and muliply by 4.

Question 16

What is bioavailability (F)?

Answer 16

How much of the drug reaches systemic circulation

Question 17

What is a maintenance dose?

Answer 17

The dose given to maintain steady state of a drug by replacing eliminated drug.

Question 18

What is the significance of therapeutic drug monitoring? (Peak and Trough)

Answer 18

Used for monitoring concentration in the blood for very toxic drugs and adjusting for patient-specific factors.

Question 19

What tests are used to determine kidney function?

Answer 19

Creatinine clearance test, which monitors creatinine levels in serum and urine.

Question 20

What does a high Volume of Distribution (Vd) indicate?

Answer 20

More drug is leaving the blood.

Question 21

What does a high Clearance (CL) indicate?

Answer 21

The body is able to eliminate the drug efficiently.

Question 22

What is capacity limited elimination also known as?

Answer 22

Zero-order elimination

Question 23

What are the extraction rations? What will get high clearance?

Answer 23

*0.7-1=high
*0.3-0.7=intermediate
*<0.3=low
*high clearance needs high extraction ration and high blood flow

Question 24

What does a high extraction ratio mean?

Answer 24

A high extraction ratio will be eliminated more quickly than a low extraction drug

Question 25

List the seven routes of drug administration.

Answer 25

* Oral * Intravenous * Intramuscular * Subcutaneous * Inhalation * Transdermal * Rectal

Question 26

The cue to use IBW

Answer 26

*This drug does not distribute into the fatty tissues *This drug stays preferentially in the bloodstream