Exam 2- Lecture 6 (Dosage Form Design Biopharmaceutical Considerations)

Question 1

The rate at which a drug reaches it site of action depends on what?

Answer 1

Absorption

Distribution

Question 2

What is absorption?

Answer 2

Passage of drug from its site of administration into the blood without being altered

Question 3

What is distribution?

Answer 3

Delivery of drug to tissues

Question 4

What is the passageway of an oral medication?

Answer 4

GI-Circulation

Question 5

What is the passageway of an IV med?

Answer 5

Circulation- goes directly blood stream so it doesn’t have to get absorbed.

Question 6

What is the passageway of IM/ SQ?

Answer 6

Tissue-Circulation

Question 7

What are the three types of physiological factors that affect drug absorption? Give examples

Answer 7

Barriers- biological membranes: several layers of cells, single layer of cells etc.
Absorption passageway- Passive diffusion, and specialized transport.
GI physiology: gastric motility and emptying, influence of food and pH

Question 8

What are the two examples of passive diffusion? Describe.

Answer 8

Transcellular: particles pass through the cell
Paracellular: particles pass in between cells

Question 9

What law can describe passive diffusion? What are the variables?

Answer 9

Fink’s law: rate of diffusion
A surface area of membrane
D diffusion coefficient
h thickness of membrane
C1 and C2 are the concentrations on each side of membrane

Question 10

What is meant by sink conditions?

Answer 10

Where you have very high concentration on one side and a small neglectable concentration on the other side.

Question 11

Sink conditions give you what type of equation?

Answer 11

First order kinetics

Rate of diffusion is directly proportional to the initial concentration

Question 12

What is partition coefficient?

Answer 12

Concentration dependent but also relative to the affinity for lipid and water.

Question 13

Diffusion coefficient of a drug depends on the particle size.
What form is absorbed? Unionized or ionized?

Answer 13

Unionized

Question 14

What drives passive diffusion for weak acids and bases?

Answer 14

Unionized fraction

Question 15

pH of the surrounding environment dictates _________ while _________ dictates the drug.

Answer 15

% of unionized form

pKa

Question 16

What is carrier mediated transport and what are the types?

Answer 16

Carrier mediated transport: the passage of molecules of transporter or carrier
Active and facilitated transport

Question 17

What are the similarities between active transport and facilitated diffusion?

Answer 17

Specific: size and shape
Saturable: too much molecules not enough transporters
Inhibitable: something with similar shape and size can interact with the carrier or transporter inhibiting the molecule from interacting.

Question 18

What are the differences between active transport and facilitated diffusion? Name examples

Answer 18

Active transport: requires energy, and is against concentration gradient.
Cancer drugs: methyldopa, 5-florouracil
Facilitated diffusion: doesn’t require energy, moves along concentration gradient (high-low). Furosemide, morphine, penicillin

Question 19

What are the types of transcytosis?

Answer 19

Phagocytosis: “cell eating”
Pinocytosis: “cell drinking”
Receptor mediated endocytosis