Suspension Dosage Forms Flashcards
What are pharmaceutical applications of suspensions?
- All new products (unless problematic)
- Paediatrics
- Geriatrics
- Administration of water-insoluble drugs
- Enteral fed patients
What should be considered in lansoprazole suspensions? (enteral feeding tubes)
*should be diluted as too viscous to administer via fine bore tube
What should be considered for augmentin suspension? (enteral feeding tube)
*should be diluted to half strength to avoid ‘caking’
What should be considered with diazepam suspension? (enteral feeding tubes)?
*not recommended due to adoption onto plastic tubing
What should be considered with sucralfate suspension? (enteral feeding tubes)
Not recommended due to ‘bezoar’
formation (aggregates of undigested
material) in patients with impaired
gastric emptying, due to binding of
sucralfate to protein in the food
Describe the way suspensions disperse
- Course dispersion in which insoluble particles, generally > 1 μm, are
dispersed within a liquid medium which is usually aqueous - Settle out
- Shake to stay suspended
What is an ideal suspension?
- Homogeneous during dosing
- Easy to re-suspend
- Proper viscosity
- Particles should be small and uniform in size
How can you work out if a suspension is flocculated or not?
work out ratio = Vs/Vt ~ h/h0
What is the system like in suspensions?
- In deflocculated systems the
particles are not associated - During flocculation, particles come
together attracted by weak forces to
form flocs
*pressure leads to close packing at the bottom = cake
How is caking prevented?
*using flocculating agents in the formulation
What are some flocculating agents?
*electrolytes (reduces electrical forces of repulsion)
*surfactants (hydrated layers around particles and formation of liquid bridges)
*polymers (structured vehicles and inter particulate interactions)
How does zeta potential affect caking?
higher zeta = caking
lower zeta = non caking
Entail what happens what Va > Vr (small)
- Weakly attracted clusters form
- Flocculation = ‘form into an aggregated lumpy or fluffy mass’
- Re-disperse upon shaking
Entail what happens when Va > Vr (large)
- Close packed arrangement at the bottom of the container
- Particles in the lowest layers are ‘pressed’ together by the weight of
the particles above → Produces a course compact mass - The repulsive barrier can be overcome and ‘caking’ can ensue
- A ‘caked’ suspension cannot be re-dispersed
What is entailed in a flocculated system?
- Particles are aggregated
- Fast sedimentation
- “Fluffy” sediment
- Large sedimentation volume
