Lipid based drug delivery system

Question 1

what are the three lipid nanoparticle classifications?

Answer 1

liquid lipid, solid lipid, solid/liquid lipids

Question 2

what are some examples of liquid lipids?

Answer 2

nanoemulsions (NEs)
lipid nano capsules (LNCs)

Question 3

what are some examples of solid lipids?

Answer 3

solid lipid nanoparticles (SLNs)

Question 4

what are some examples of solid/liquid lipids?

Answer 4

nanostructure lipid capsules (NLCs)

Question 5

what are the types of emulsions?

Answer 5

Oil-in-water (o/w)
water-in-oil (w/o)

Question 6

what type of emulsion can be injected IV?

Answer 6

o/w only

Question 7

what type of emulsion tend to deliver hydrophobic drugs?

Answer 7

o/w only

Question 8

what type of emulsion tend to deliver hydrophilic drugs?

Answer 8

w/o only

Question 9

what do nano emulsions contain?

Answer 9

oil -vegetable oil/medium chain triglycerides
water
stabiliser - phospholipids (often lecithin)

Question 10

what are the methods to manufacturing nano emulsions?

Answer 10

1. high energy methods
   - ultrasound
   - high shear homogenisation
   - high speed homogenisation
2. low energy methods
   - phase inversion method

Question 11

whats the advantage of nano emulsions?

Answer 11

1.active targeting possible
- modify phospholipids
-modify functional PEG
2. lower viscosity vs coarse emulsion due to lower particle size
- better for injections

Question 12

how do nanoemulsions destabilise?

Answer 12

thru…
Oswald ripening of polydispersed particle size
sedimentation/creaming
brownian motion

Question 13

what type of emulsions are these examples?
-hydrophobic drugs
-vaccines
-parenteral nutrition

Answer 13

-hydrophobic drugs = o/w
-vaccines =w/o
-parenteral nutrition= o/w

Question 14

why are nano emulsions used in vaccines?

Answer 14

as it’s an adjuvant, allowing a strong immune response

Question 15

what are features of SLN?

Answer 15

solid at room temp. soften at body temp.
o/w
similar to NLCs

must be… biocompatible/biodegradable/GRAS (generally recognised as safe)

Question 16

How are SLNs produced?

Answer 16

HIGH PRESSURE homogenisation
1. melt the lipid; add drug for drug loading particles
2. homogenisation
-hot (to emulsify and homogenise)
not good for thermaliable drugs
-cold using liquid nitrogen or dry ice (dispersed in water + surfactant =forms a suspension)

Question 17

when is drug loading used in SLN? And how?

Answer 17

• hydrophobic drugs,
• macromolecules, water soluble low MW drugs - minimise affinity of drug in aq. phase by using cold homogenisation

Question 18

what does the amount of drug loaded in SLN depend on?

Answer 18

• the solubility of the drug in the lipid melt
• the miscibility of the melted drug and lipid
• the structure of the solidified lipid matrix
• lipid polymorphism

Question 19

which has better drug loading… NLCs or SLNs?

Answer 19

NLCs

Question 20

why is using a hot temperature for homogenisation good?

Answer 20

increases the solubility of the drug in water

Question 21

why is using a cold temperature for homogenisation bad?

Answer 21

solidified lipid from the core outwards, this will cause a burst drug release

Question 22

when are NLCs preferred over SLNs?

Answer 22

• a low drug loading
• stop release of encapsulated drug during storage

Question 23

what are the features of LNCs?

Answer 23

oil phase - medium chain triglycerides
aqueous phase - saline solution
surfactant - poly(ethylene glycol)660 + free PEG
-phospholipid

presence of a semi-solid rigid shell

Question 24

when are LNCs mainly used?

Answer 24

hydrophobic drugs

Question 25

what are the advantages of LNCs?

Answer 25

no special equipment needed
reproducible preparation
stable over time
useful for a wide range of therapeutics
low toxicity
solvent-free preparation

Question 26

what are the dis-advantages of LNCs?

Answer 26

potential toxicity of excess surfactants
loading may require solvents
limited to 100nm particles
surfactant modification through PEGylation