L44- Drug Solubility & solution formualation

Question 1

net work of 2w₂₂ is equal to?

Answer 1

The engergy required to remove one molecule from a solute.

Question 2

net work of w₂₂ is equal to?

Answer 2

net work when the hole from removal of one molecule of a solute from a solute is closed and half the enegry is regained.

Question 3

net work of w₁₁ is equal to?

Answer 3

enegry needed to create a hole large enough to accomadate a free solute molecule.

Question 4

net work of -2w₁₂?

Answer 4

energy is gained by placing the solute into the solvent cavity.

Question 5

what factors affect dissolution of a solid in a liquid?

Answer 5

• crystal properties
• degree of ionisation
• interactionof substituent groups with the solvent
• molecular size

Question 6

how does crystal properties affect dissolution?

Answer 6

• you need to measure the strenth of the crystal lattice in the solid
• melthing point of the solid can be used

Question 7

what factors affect these work processes?

Answer 7

• strength of solute-solute bonds
• strenth of solvent-solvent bonds
• solute-solvent interactions

Question 8

how does strength of solute-solute bonds affect work?

Answer 8

• increases w₂₂
• bond strenth correlates with melting point
• if melting point is greater than 200-250 degrees solubility could be an issue.

Question 9

how does strength of solvent-solute bonds affect work?

Answer 9

• increasing solvent-solute interaction strength increases w₁₁
• to insert solute into solvent cavity many contacts are required
• bigger molecule=more contacts needed

Question 10

how does substituent groups influence solubility of molecules in water?

Answer 10

-some substituents asre hydrophobic and some are hydrophilic

Question 11

wha are some external factors that will affect solubility of a molecule?

Answer 11

• temperature
• degree of ionisation
• pH

Question 12

What is dielectric constant?

Answer 12

constant of a solvent relects its ability to accomodate seperation of charge.

Question 13

what is co-solvents?

Answer 13

the combination of solvents to increase their solubility.

Question 14

what does the diffusion coefficient describe?

Answer 14

the ease with which a molecule can diffuse through a medium

Question 15

what are the 6 methods to increase drug solubility?

Answer 15

• drug micronisation
• co-solvents
• pH modification
• salt formation
• complexation
• drug modifications

Question 16

how does changing pH affect solubility?

Answer 16

changing pH, increases ionisation of the drug, which therefore increases solubility

Question 17

what is a cyclodextrin?

Answer 17

cyclic saccharide