#4

Question 1

Why are so many drugs in pill form?

Answer 1

Because the enter you system slower, and make it harder to OD.

Question 2

The _____ the PC (partition coefficient) the more likely the drug will be absorbed by passive diffusion.

Answer 2

Larger the PC

Question 3

______ molecules are more likely to be absorbed by passive diffusion.

Answer 3

smaller molecules

*Lipophilic molecules also use this method.

Question 4

What is PC (partition coefficient)?

Answer 4

How well a chemical can enter cell membrane (olive oil) *Higher = more likely to cross membrane.

Question 5

Do charged molecules enter the cell membrane well?

Answer 5

No!

Question 6

How does pH effect passive diffusion of drugs?

Answer 6

Acidic drugs are absorbed more in the stomach. (acidic pH in stomach)

Basic drugs are absorbed more in the small intestines. (intestine pH is 3-7)

Question 7

_________Transporters can kick drugs out of cells.

Answer 7

ABC transporters (use ATP) *active transport

Question 8

_______ Transporters are important for transport of certain drugs that are organic acids or bases.

Answer 8

SLC Transporters (Exchange Na+ or K+)

Question 9

What factors affect oral absorption of drugs?

Answer 9

• pH
• surface area
• Gastric emptying time (time in stomach)
• dosage form
• Drug inactivation

Question 10

What are the other routes to administer drugs other than oral?

Answer 10

• inhalation
• intravenous
• Intramuscular
• Subcutaneous
• Topical

Question 11

Describe distribution of drug through tissues….

Answer 11

A. Capillary penetration to the interstitial fluid.
B. Entry into cells from interstitial fluid.
C. Restricted distribution into CNS-blood brain barrier.

*No gaps in endothelium, sheaths surrounds, drugs efficiently transported out of epithelium back into blood stream.

Question 12

Which drugs are faster? Water soluble or Lipophilic?

Answer 12

Lipophilic are faster

*Water soluble drugs go through endothelial gaps are slower.

Question 13

What is Volume of Distribution?

Answer 13

Indication of how much a drug is distributed, based on how much is in the plasma and how much was added.
*Q/C =Vd
Q = amount of drug administered
C= concentration of drug in plasma at Eq.

Question 14

Average person volume = ?

Answer 14

3 liters of plasma
9 liters of interstitial space
29 liters cells
TOTAL = 41 liters

• IF a drug never leaves blood/plasma Vd = 3 liters
• IF drug distributed equally everywhere Vd = 41 liters.

Question 15

Describe the 2 phases of drug metabolism..

Answer 15

Phase 1 = add (uncover) functional group

Phase 2 = Conjugation

Question 16

______ is the most important place for drug metabolism.

Answer 16

The liver

Question 17

What role does the Smooth E.R of hepatocytes? What types of chemical rxns are taking place here?

Answer 17

It has membrane bound enzymes that metabolize drugs.
Chemical rxns going on here:
1. Oxidations (P450 enzymes, Flavin monooxygenases)
2. Reductions (Some hepatocyte, mainly enteric bacteria)
3. Hydrolysis (ester and amides)
4. Dehalogenation
5. Glucuronide conjugation

Question 18

_________ are designed to remove foreign substances.

Answer 18

Microsomal enzymes

Question 19

_______ is when drug mimics natural substance.

Answer 19

Non-microsomal metabolism

1. oxidation
2. reductions
3. hydrolysis
4. conjugation

Question 20

What are the 6 factors that affect drug metabolism?

Answer 20

1. Entry into lever (usually slow into the liver and fast once in)
2. Enzyme inhibition
3. Enzyme induction
4. Genetics
5. Age
6. Pathology

Question 21

What are the 3 components of drug excretion?

Answer 21

1. glomerular filtration
2. tubular reabsorption
3. active transport

Question 22

What is the major filter of glomerular filtration?

Answer 22

The basement membrane

Question 23

Drugs that are filtered but not reabsorbed or secreted back clear at ______.

Answer 23

130 mL/min

*If Vd is 12 L the drug will have a t1/2 of about 1 hr in the plasma.

Question 24

Drugs that are actively secreted and not reabsorbed may clear as fast as _______.

Answer 24

650 mL/min

*If Vd id 12 L the drug will have a t1/2 of about 13 min in the plasma