Drug Delivery from Synthetic Polymeric Microparticles (G2)

Question 1

List 2 biodegradable polymers, approved by the FDA for drug delivery

Answer 1

PLGA and PLA

Question 2

Explain how lactic acid can be used to synthesise PLLA, PLDA and PDLA

Answer 2

Question 3

Name 2 methods used to fabricate drug loaded biodegradable particles

Answer 3

Spray Drying
Emulsification + Solvent evaporation

Question 4

Explain how Spray Drying produces drug loaded particles

Answer 4

1) Drug + Polymer + Solvent in mixed together in a chamber
2) The slurry is dispersed via a nozzle/atomiser to a controlled drop size
3) Hot gas flowing in the same direction as the liquid dries the droplets
4) The uniform droplets are collected at the bottom

Question 5

Emulsification can be split into 2 further categories, what are these and when are they employed?

Answer 5

Single and double emulsion
- Single: Used for hydrophobic drugs (in water)
- Double: Used for hydrophilic drugs (in organic solvent)

(Don’t want the drug to dissolve)

Question 6

Explain how single emulsion produces drug loaded particles

Answer 6

1) Start with a:
Dispersed phase of: Polymer + Drug both dissolved in an inorganic solvent
Continuous Phase: Aqueous solution of water + Stabiliser (PVA)
2) Emulsify the 2 phases
3) Evaporate the organic Solvent, left with drug loaded particles stabilised by the polymer and PVA in water.

Question 7

What is the purpose of emulsifiers or stabilisers and how do they work?

Answer 7

They are molecules with a hydrophilic and hydrophobic end. They form a film around a globule of one phase, preventing the globules from joining together again, hence stabilising the emulsion.

Question 8

What are some key requirements for the solvent in single emulsion?

Answer 8

Immiscible with water, Soluble for polymer and drug, and highly volatile for evaporation

Question 9

Describe Double emulsion and how it produces microparticles

Answer 9