Absorption

Question 1

Why does the dissolution rate effect absorption rate?

Answer 1

Because the drug must be in solution before it can be absorbed

Question 2

Main site of disintegration and dissolution?

Answer 2

Stomach

Question 3

Why is absorption in the stomach minimal?

Answer 3

Because it has a mucosal layer and small surface area.

Question 4

Which drugs, weak acids or weak bases, are more likely to be absorbed in the stomach and why?

Answer 4

Weak acids. Because they are unionised at the low pH of the stomach

Question 5

Compare the absorption in the small and large intestine

Answer 5

Small = most absorption happens here. Due to villi and micro villi = massive surface area 
Large = limited absorption - mostly preparing for excretion

Question 6

Name some factors that will influence absorption

Answer 6

Dissolution, gastric motility, drug interactions, passive through gut wall

Question 7

Compare facilitated transport and paracellular transport

Answer 7

Both passive.
Paracellular = through a pore filled with fluid - hydrophilic drugs
Facilitated = involved a carrier molecule (e.g. transport protein)

Question 8

The rate of absorption is proportion to the amount of drug remaining unabsorbed in the GTI for which absorption kinetics - first or zero order?

Answer 8

First

Question 9

Zero order kinetics typically involves which absorption mechanisms?

Answer 9

Active transport or carrier mediated

Question 10

Compare zero and first order kinetics

Answer 10

Zero = absorption rate is constant and completely independent of how much drug has been absorbed so far. First = opposite.

Question 11

True or false. As more drug is absorbed, the elimination part of the kinetics equation becomes less important.

Answer 11

False. Becomes more important.