Y1 Solubility Intro

Question 1

Define Solubility

Answer 1

Extent to which molecules transition from the solid state to the liquid state (dissolution)

The amount of a chemical substance that has passed in solution at equilibrium

Question 2

Define Solution

Answer 2

Mixture of at least two components: solvent (liquid) and solute (solid)

A system in which molecules of solute are dispersed in solvent vehicle

Question 3

What is a saturated solution?

Answer 3

When solubility rate is reached (given temp/pressure) - additional solid will not dissolve (supersaturated)

Question 4

Factors affecting a drugs solubility?

Answer 4

Solid state of drug
Polymorph type
Salts + counter ion
Composition of aqueous media 
pH (buffer components)
Ionic strength of solution 
Temperature

Question 5

What is miscibility?

Answer 5

The solubility of one liquid in another liquid

immiscible liquids do not mix e.g. water and oil

partially = layers/droplets

Question 6

What is a co-solvent?

Answer 6

Used to increase solubility for desired therapeutic effect

Achieving appropriate solvent polarity

Requires interaction between solute/solvent

Influence of forces: london, hydrogen bonds, dipole-dipole

Question 7

Process of solubility

1. What factors are involved?
2. Process (3 step)

Answer 7

1. interactions, forces and organisation of molecules in solid and liquid state
2. • Removal of solute molecule (breaking forces)
   • Break forces in liquid to create a cavity/opening
   • Insertion of solute molecule into solvent - forces needed to keep solute in solution

Question 8

How to create a system of optimum polarity?

Answer 8

Mix solvents with different polarities to solubilise an API

Question 9

Common solvents?

Answer 9

Most are toxic, limited to:

water, ethanol, glycerin, PG, PEG and sorbitol