Pharm Solids, Crystal

Question 1

How does crystallization begin?

Answer 1

Nucleation

Question 2

Crystallization is energetically “uphill” until when?

Answer 2

Critical nucleus size

Question 3

What are two ways crystals can form from monomers?

Answer 3

Classical nucleation theory

Two-Step Nucleation theory

Question 4

What is the classical nucleation theory?

Answer 4

When monomers cluster to form nuclei

Question 5

What is the Two-Step Nucleation theory?

Answer 5

Monomers cluster to form condensed phase. Then they rearrange in the condensed phase

Question 6

What is a polymorphism?

Answer 6

The ability of a substance to exist in two or more crystalline phases that differ in the arrangement and/or conformation.

Question 7

What are 4 changes that can cause a polymorphism?

Answer 7

Solubility
Physical/chemical stability
Bioavailability
Processability

Question 8

What is monotropic?

Answer 8

When form 1 is more stable than form 2 at all temperatures

Question 9

What is Enantiotropic?

Answer 9

When form 1 is more stable than form 2 at one temperature, but visa versa is true at a different temperature.

Question 10

Are solvates and hydrates more soluble or insoluble than crystallines?

Answer 10

Insoluble because of hydrogen bonds of water

Question 11

What are like salts, but do not have a transfer of a proton?

Answer 11

Co-Crystals

Question 12

What can stabilize amorphous crystals?

Answer 12

Polymers-Creates an amorphous dispersion

Question 13

What does DSC stand for?

Answer 13

Differential Scanning Calorimetry

Question 14

What does DSC do?

Answer 14

Monitors amount of heat needed to keep two samples at the same temperature

Question 15

What are 6 ways to figure out what compound that you have?

Answer 15

DSC
Gravimetric-weight change
Solubility, dissolution rate
X-ray diffraction-good for crystals
Spectroscopic