Lecture 2: preformulation considerations 1

Question 1

Why do we need preformulation studies?

Answer 1

1. The physicochemical properties of the molecule affect how it would be processed pharmaceutically, and how it is handled in the human body.
2. Knowing these early in the process will help to narrow down the drug candidates –> this is what preformulation does

Question 2

What are intrinsic properties of a drug?

Answer 2

The properties that are inherent to the molecule and can only be changed by chemical modifications.

Question 3

What are the bulk properties of a drug?

Answer 3

The properties that are the result of intermolecular interactions and can be affected by physical shape and form, as well as environmental factors.

Question 4

What is the distribution law?

Answer 4

1. A solute added to a mixture of two immiscible solvents, in an amount insufficient to saturate the solvents, will become distributed between the two solvents in a definite concentration ratio at equilibrium.
2. The distribution law is applicable to a solute that is able to dissolve in the two solvents

Question 5

How do you calculate partition coefficient?

Answer 5

P = Co / Cw

Question 6

What can you conclude if log P is greater than zero?

Answer 6

The drug dissolves better in octanol

Question 7

What can you conclude if log P is less than zero?

Answer 7

The drug dissolves better in water

Question 8

What is the purpose of the shake flask method?

Answer 8

To measure the partitioning coefficient of the drug

Question 9

What is the process of the shake flask method?

Answer 9

in progress because the slide is weird

Question 10

How do you calculate apparent distribution coefficient?

Answer 10

D = Co / (Cw ionised + Cw unionised)

Question 11

What’s the difference between partitioning and true distribution coefficent?

Answer 11

Unlike distribution coefficient, the Cw of partition coefficient doesn’t take the ionized form of the drug into account

Question 12

Define diffusion.

Answer 12

Diffusion is the movement of molecules from one region to another brought about by the random molecular motion of individual molecules along a concentration gradient.

Question 13

What are factors that affect the rate of diffusion?

Answer 13

Temperature
Pressure
Viscosity
Molecular weight

Question 14

What is the relationship between molecular weight and diffusion coefficient?

Answer 14

They are inversely related

Question 15

What are Bronsted Lowry acids and bases?

Answer 15

Bronsted Lowry acid is a substance which donates a proton
Bronsted Lowry base is a substance which accepts a proton

Question 16

Can the ionized form of a drug pass the lipid membrane?

Answer 16

no

Question 17

By which process do most drugs get transported to the systemic circulation?

Answer 17

Passive diffusion

Question 18

Would drugs that are weakly acidic be absorbed better in the stomach or the small intestine?

Answer 18

Stomach because it has a lower pH, which means the extent of ionization of the drug will be low.