Introduction to medicinal products - dissolution

Question 1

What is the features of a pure drug?

Answer 1

Drug substance
Active pharmaceutical ingredient
medicinal agent
active principle
drug powder
drug

Question 2

What is features of drug and excipients?

Answer 2

Drug product
Medicinal product
Formulations
Medicine
Drug
- May include the primary and secondary packaging

Question 3

what is pharmaceutics?

Answer 3

The process of turning a drug substance into a medicinal product to be used safely and effectively by patients (formulation)

Question 4

What are the 3 pillars of pharmaceutics?

Answer 4

• Bio-physico-chemical properties of drug product and drug substance
• bio pharmaceutical considerations
• patient centres, therapeutic considerations

Question 5

What is the order of onset time of drug routes

Answer 5

Intravenous
Intramuscular
Sub-cutaneous

Question 6

How can dissolution rate be measured?

Answer 6

Noye-whitney equation

Question 7

What are some factors effecting pharmaceutics?

Answer 7

• Partition coefficient (Log P): ability to diffuse across membranes
• Stability: chemical, physical and biological
• oranoleptic properties
  -powder properties

Question 8

What molecules can be absorbed immediately?

Answer 8

Drugs in solution because molecules are dispersed eg liquid paracetamol has more rapid onset than tablets

Question 9

What is a solution?

Answer 9

a mixture of two or more components that form a single, homogeneous phase

Question 10

What is a solution?

Answer 10

a mixture of two or more components that form a single, homogeneous phase

Question 11

what is dissolution?

Answer 11

a process by which a solid dissolves in a solvent to produce a solution

Question 12

what is the solubility of a substance?

Answer 12

the amount that goes into a solution when equilibrium is established between the solute in solution and excess (undissolved) substance

Question 13

What happens to a tablet during drug absorption?

Answer 13

Tablet has slow dissolution rate, it begins to disintegrate into granules (dissolution is intermediate) and then deaggregation (dissolution is fast) occurs to form fine particles. When drug is in solution it is able to be absorbed and can enter the bloodstream

Question 14

What are the symbols of the noyes whitney equation and their meaning?

Answer 14

dm/dt - rate of dissolution of drug particles
D = diffusion coefficient
A = effective SA of drug particles
h= thickness of the diffusion layer
Cs= saturated solubility
C = concentration in the bulk solubility

Question 15

What are the key factors of dissolution rate?

Answer 15

Particle size and drug solubility

Question 16

What happens to dissolution rate if you reduce particle size

Answer 16

Increases

Question 17

What happens to dissolution if you decrease porosity?

Answer 17

Decrease

Question 18

What happens if the thickness of boundary layer increases (reduced mixing)?

Answer 18

Dissolution decreases

Question 19

what happens to dissolution if you increase drug solubility

Answer 19

Increases

Question 20

what happens to dissolution if you increase drug solubility

Answer 20

Increases

Question 21

What happens to dissolution if you decrease diffusion coefficient (increasing viscosity)

Answer 21

Decreases

Question 22

What are other components affecting dissolution?

Answer 22

Stomach contents (food components, pH buffer capacity)

GI motility (transit/emptying of stomach, gastrointestinal secretions)

Question 23

What are other components affecting dissolution?

Answer 23

Stomach contents (food components, pH buffer capacity)

GI motility (transit/emptying of stomach, gastrointestinal secretions)

Question 24

What does pharmacopeia BP and EP mean (book with drugs and there use as medicines)

Answer 24

British pharmacopeia and European pharmacopeia

Question 25

What is the solution process?

Answer 25

1. drug molecule is removed from its crystal
2. a cavity from the molecule is created in the solvent
3. the drug molecule inserts into this cavity

Question 26

What are factors effecting solubility ?

Answer 26

1. Temperature (collision theory- more energy, more rapid solubilisation)
2. Molecular structure ( shape and SA, Hydrophobicity and degree of ionisation)
3. Nature of solvent (PH and solvents, solubilising agents)
4. Crystal characteristics

Question 27

How does a higher temperature affect stability of a crystal?

Answer 27

Higher temp = more stability (less likely to break down)

Question 28

How does large surface areas affect solubility ?

Answer 28

Lowers it

Question 29

How does polar/non-polar groups affect solubility?

Answer 29

Polar groups increase solubility
non-polar groups decrease it

Question 30

how does ionisation effect solubility?

Answer 30

Increases it

Question 31

What is partitioning of drugs?

Answer 31

Due to a difference in solubility in different phases the drugs will partition between 2 solvents (2 phases of polar and non-polar of a drug)

eg. between aqueous and lipid phases
antibiotics partitioning into microorganisms

Question 32

what is log P?

Answer 32

The partition coefficient
Measure of lipophilicity/hydrophilicity - unionised

Question 33

What does a log P greater than 0 and less than 0 mean,

Answer 33

Log P > 0; lipophilic
Log P <0; hydrophilic

Question 34

What are the different types of solids?

Answer 34

1. Ionic solids
2. Molecular solids
3. Molecular salts

Question 35

What is polymorphism?

Answer 35

When compounds can crystallise out of solution into a variety of different habits depending on the conditions ( usually have the same structure but can also crystallise with different structures)

Question 36

What are features of the DVLO theory?

Answer 36

The repulsive energy is electrostatic forces
The attractive energy is vdw forces
The theory helps predict stability of pharmaceutical suspensions
The primary minimum leads to coagulation