Liquid and Solutions & Crystalline and Amorphous Particles

Question 1

Define solution

Answer 1

A mixture of 2 or more components that form a single phase and is homogenous to a molecular level

Question 2

Which functional groups make the compound soluble in water

Answer 2

1. -NH, C=O , -OH will hydrogen bond with water

Question 3

As more benzene rings appear in the molecular structure, the solubility level Is “practically insoluble”
Provide an example

Answer 3

• YES
• Testosterone

Question 4

Ions are freely soluble?

Answer 4

YES

Question 5

List 1 characteristic of a salt-form of a drug

Answer 5

Has better absorption rate therefore faster action

Question 6

Define salting out

Answer 6

The precipitation of peptides and proteins from a solution at high concentrations: when salt conc. are high, the water molecules bind to the salt instead of the protein.

Question 7

Define Van Der Waals Radius

Answer 7

The imaginary hard radius of an atom/molecule only

Question 8

Define hydrodynamic radius

Answer 8

The imaginary hard radius of an atom/molecule and any bound drug particles

Question 9

What factors influence diffusion rate and how?

Answer 9

1. High Temperature - faster
2. Water to peanut oil - slower
3. Neutral to salt form - slower
4. water to ethanol for a very soluble drug - faster
5. nanoparticle formulation - slower

Question 10

Define amorphous

Answer 10

no organised structure; high energy state of the drug; less bonds formed

Question 11

Define crystalline

Answer 11

Crystal Type 1: structural pattern can be observed; low energy state: increased bonds
Crystal Type 2: higher structural pattern; even a lower energy state

Question 12

Outline the serious real-world example.

Answer 12

A new crystalline structure was found in the Ritonavir drug called Needle-like crystals. They had a very low solubility of 19mg/ml compared to the plate like crystals with a solubility of 90mg/ml.

New: couldn’t be stored in the fridge
Original: could be stored

Question 13

Outline the process of spray-drying (methods of solid-drug production)

Answer 13

1. Drug is dissolved in a solvent
2. With spraying solvent evaporates
3. Formation of amorphous powder

Question 14

Outline the process of freeze-drying

Answer 14

1. Drug is dissolved in a solvent = solution
2. Solution is frozen
3. Sample placed under vacuum
4. Solvent goes from solid to gas
   phase
5. Formation of amorphous particles

Question 15

Outline the process of slow evaporation

Answer 15

1. Drug is dissolved in a solvent
2. Heat exposure to remove solvent
3. Drug crystallises out
4. Formation of large-size crystals

Question 16

Outline the process of precipitation

Answer 16

1. Drug is dissolved in a solvent
2. Addition of another solvent which is miscible with another solvent
   3.Drug precipitates out, forming amorphous or crystalline parts

Question 17

Amorphous drugs are always more soluble than crystalline drugs. Is this true

Answer 17

YES