Physiochemical Properties of Drugs II

Question 1

What is the pH-Partition Hypothesis on Drug Absorption?

Answer 1

The gastrointestinal and other biological membranes act like lipid barriers.
The un-ionized (lipophilic) form of the acidic or basic drug is preferentially absorbed.
Most drugs are absorbed by passive diffusion.

Question 2

What factors help predict whether a drug will be absorbed or not?

Answer 2

Degree of ionization of a molecule.
pKa values of the acidic or basic functional groups.
pH of the environment

Question 3

If a drug exists primarily in the unionized form it will be highly absorbed or not absorbed?

Answer 3

Highly absorbed.

Question 4

Acidic drugs will be better absorbed in an acidic environment or a basic environment?

Answer 4

Acidic drugs exist in unionized form in acidic environment and are absorbed well.

Question 5

Basic drugs will be better absorbed in an acidic environment or a basic environment?

Answer 5

Basic drugs exist in unionized form in basic environment and are absorbed well.