Kinetics

Question 1

Study of the different processes a drug undergoes as it reaches and leaves the biologic site of action.

Answer 1

Pharmacokinetics

Question 2

What the body does to the drug.

Answer 2

What does pharmacokinetics describe?

Question 3

What is the dominant transport process?

Answer 3

Passive Transport.

Question 4

Does passive transport require energy?

Answer 4

No, it is non-energy requiring.

Question 5

What direction does movement occur in passive transport?

Answer 5

Along the concentration gradient; downhill, from High to Low.

Question 6

Which transport process is the slowest?

Answer 6

Passive Transport.

Question 7

What is Fick’s Law of Diffusion used for?

Answer 7

To describe the rate of transport of a drug.

Question 8

Fill in the blank: In Fick’s Law, 𝜕𝑄/𝜕𝑇 = 𝐴𝑑/ℎ (C1 – C2), 𝜕𝑄/𝜕𝑇 = _______.

Answer 8

rate of transport.

Question 9

What does ‘A’ represent in Fick’s Law of Diffusion?

Answer 9

Surface area of the membrane.

Question 10

What does ‘D’ represent in Fick’s Law of Diffusion?

Answer 10

Diffusion coefficient.

Question 11

What factors affect the transport process?

Answer 11

• Surface Area
• Concentration Gradient
• Thickness of Membrane
• Diffusion Coefficient

Question 12

How does surface area affect the rate of transport?

Answer 12

Increased surface area increases the rate of transport.

Question 13

How does concentration gradient affect the rate of transport?

Answer 13

Increased concentration gradient increases the rate of transport.

Question 14

How does thickness of the membrane affect the rate of transport?

Answer 14

Increased thickness decreases the rate of transport.

Question 15

What does the diffusion coefficient describe?

Answer 15

The ease of movement of the drug in relation to the membrane of transport.

Question 16

What does C1 - C2 represent in Fick’s Law?

Answer 16

Concentration difference/gradient.

Question 18

What is the diffusion coefficient?

Answer 18

It describes the ease of movement of a drug in relation to the membrane of transport.

Question 19

What does H represent in the context of diffusion?

Answer 19

H represents the thickness of the membrane.

Question 20

What does C1 - C2 represent?

Answer 20

C1 - C2 represents the concentration difference or gradient.

Question 21

What factors does the diffusion coefficient depend on?

Answer 21

particle size and lipophilicity.

Question 22

How does particle size affect diffusion?

Answer 22

Decreased particle size increases surface area and coverage of the membrane for transport.

Question 23

What is the relationship between lipophilicity and the diffusion coefficient?

Answer 23

Increased lipophilicity results in a higher diffusion coefficient and faster transport.

Question 24

What is the degree of ionization’s effect on drug transport?

Answer 24

The unionized form of a drug is more likely to cross the membrane.

Question 25

How does pKa affect weak acids in terms of lipophilicity?

Answer 25

For weak acids, a smaller Ka (or higher pKa) results in more unionized form, increasing lipophilicity and transport rate.

Question 26

How does pKa affect weak bases in terms of lipophilicity?

Answer 26

For weak bases, a higher Ka (or lower pKa) results in more unionized form, increasing lipophilicity and transport rate.

Question 27

What is the lipid-water partition coefficient?

Answer 27

It is the ratio of solubility of a drug in lipid to its solubility in water.

Question 28

What is the conclusion regarding lipid-water partition coefficient and diffusion?

Answer 28

The higher the lipid-water partition coefficient, the more lipophilic the drug, leading to a higher diffusion coefficient and transport rate.

Question 29

What are the characteristics of carrier-mediated transport?

Answer 29

Specificity/selectivity, subject to competition, inhibition or antagonism, poisoning, and saturability.

Question 30

What is active transport?

Answer 30

It is energy-dependent, uphill transport, and is the fastest form of transport.

Question 31

What is an example of active transport?

Answer 31

Na+/K+ ATPase.

Question 32

What type of transport is facilitated transport?

Answer 32

Non-energy-dependent ## Footnote Facilitated transport occurs downhill and is the fastest form of transport.

Question 33

Which transport mechanisms involve movement through water-filled pores or channels?

Answer 33

Convective Transport ## Footnote Convective transport is limited by pore size, allowing movement of particles with molecular weight (MW) ≤ 150-400.

Question 34

What factors limit convective transport?

Answer 34

* Pore Size or Diameter * Charge of the Pore Lining * Electrochemical Gradient * Solvent Drag ## Footnote Movement is also limited by the charge of the pore lining.

Question 35

What is Ion-Pair Transport?

Answer 35

Movement of ions that cannot pass through pores and do not have carriers ## Footnote It involves the formation of a neutral complex from exogenous and endogenous ions.

Question 36

Define LIBERATION in the context of drug administration.

Answer 36

Release of drug from the drug product or dosage form ## Footnote The objective is to convert the drug into an aqueous solution.

Question 37

What are the factors affecting drug liberation?

Answer 37

* Biopharmaceutic factors * Pharmacotechnical factors * Dissolution Rate * Disintegration Rate * Hardness * Coating ## Footnote Liberation can be a highly modifiable process.

Question 38

Fill in the blank: For drugs given PO, exemption to Liberation is _______.

Answer 38

[Solution] ## Footnote This indicates that solutions do not require liberation as they are already in aqueous form.

Question 39

What are types of intentionally-modified liberation?

Answer 39

* Modified-release dosage form * Delayed Type: ECT * Sustained/Extended Type: Prolonged Release, Extended Release, Sustained Release ## Footnote These types are designed to alter the release profile of the drug.

Question 40

Physiologic: the rate and extent of disappearance of the drug from the site of administration Pharmacokinetic: the rate and extent of drug entry into the systemic circulation

Answer 40

8 ABSORPTION

Question 41

Measure of how fast and how much of the drug entered systemic circulation

Answer 41

Bioavailability. F

Question 43

2 methods of determining F

Answer 43

Urinary excretion data Blood concentration vs time data