Polymorphism T2

Question 1

What are polymorphs

Answer 1

Different crystals of the same chemical
e.g. carbon (graphite/diamond)

Question 2

What are amorphous

Answer 2

Disordered state

(NOTES FROM REVISION SLIDE - , not packed in repeated ordered fashion / lacks long range order, prepared by rapid precipitation / cooling, spray drying / freeze drying. Have glass transition (Tg).)

Question 3

What are solvates

Answer 3

(pseudopolymorph) solvent molecules incorporated in the crystal lattice

Question 4

what are salts

Answer 4

generally have higher water solubility and bioavailability

Question 5

What are co crystals

Answer 5

non-volatile molecules incorporates into crystal lattice

Question 6

Polymorphs have different physical properties, what are these?

Answer 6

Hygroscopicity,
solubility / dissolution,
melting point,
density,
chemical / physical stability,
hardness,
compression,
manufacturability

Question 7

stable polymorph

Answer 7

represents the lowest energy state, has the highest melting point and least aqueous solubility.

Question 8

Metastable polymorphism

Answer 8

higher energy state, have lower melting points and higher aqueous solubilities.

Question 9

Polymorphic transitions can occur with:

Answer 9

solvents, temperature, pressure, cooling rate, crystallisation, milling, granulating, drying and compressing

Question 10

Analytical Technique Characterisation

Answer 10

Crystallography; x-ray diffraction pattern
Nonequivalent crystal structure
Microscopy (SEM)
Thermal analysis; DSC and TGA
Infrared absorption, and Raman spectroscopy
Solid-state nuclear magnetic resonance
Solubility & dissolution studies