PHARM: Drug Absorption, Distribution, and Excretion

Question 1

What is drug distribution?

Answer 1

The process of binding of a drug to a plasma protein, a tissue compartment, or a receptor site

Question 2

What is the order (from fastest to slowest) that barbitol, thiopental, hexobarbital, and phenobarbital are metabolized?

Answer 2

Thiopental, barbital, hexobarbital, phenobarbital

Question 3

What is the partitioning coefficient (Kp)?

Answer 3

[drug]lip/[drug]aq

Question 4

What is the effect of oxygen, sulfur, and nitrogen on the partitioning coefficient?

Answer 4

Decreases (makes more hydrophilic)

Question 5

True or False: Drugs with a higher partitioning coefficient would pass more slowly through a cell membrane.

Answer 5

False

Question 6

What does pK represent with regards to drug ionization?

Answer 6

pK is the pH at which a drug will be 50% ionized and 50% non ionized

Question 7

True or False: If a drug is ionized in a particular biologic fluid, it has a tendency to stay there and accumulate

Answer 7

True

Question 8

What is filtration? What limits distribution in this fashion?

Answer 8

Transfer through pores/ fenestrations in capillaries; molecular weight/ size

Question 9

What mechanisms of drug transport are saturable?

Answer 9

Active transport, facilitated diffusion, receptor-mediated endocytosis

Question 10

What are the two major routes of drug administration?

Answer 10

Enteral (through the GI) or Parenteral (outside the GI tract)

Question 11

What are the routes of parenteral drug administration?

Answer 11

Intravenous, intramuscular, subcutaneous, inhalational, transdermal

Question 12

What are the advantages and disadvantages of IV drug administration?

Answer 12

Advantages- no absorption; attain desired drug concentration more rapidly, can adjust dosage more readily, can administer irritating solutions, bypasses first-pass effect; Disadvantages- risk of infection, pain/difficult self-admin., no drugs that precipitate in blood or oily vehicles

Question 13

What is the first-pass effect?

Answer 13

The SI and liver contain a lot of the metabolic enzymes that degrade drugs and so enteral administration causes the drug to be exposed to those enzymes before systemic circulation

Question 14

What is the mechanism by which a drug administered intramuscularly is absorbed?

Answer 14

Filtration

Question 15

How can the absorption rate of a drug delivered IM be altered?

Answer 15

Changing muscle to muscle with different flow or by changing the drug vehicle

Question 16

What method of parenteral drug admin provides slow and constant absorption

Answer 16

Subcutaneous

Question 17

True or False: inhalational administration can be for both systemic and local effects?

Answer 17

True

Question 18

What are the disadvantages of inhalational drug administration?

Answer 18

Cumbersome administration and difficulty in dosage regulation

Question 19

What is the transport mechansim by which drugs are absorbed transdermally?

Answer 19

Passive diffusion

Question 20

What are the disadvantages of enteral administration?

Answer 20

Gastric irritation, destruction of drugs in GI, irregular absorption, patient cooperation, first-pass effect

Question 21

What is the primary site of drug absorption?

Answer 21

Small intestine