Study Set Content:
Low temp. Oswald ripening
HIgh temp. Oswald ripening
small particles in suspension seem to disappear and large particles grow after repeated temperature changes in both directions
Ostwald ripening
aggravates this situation, with the result that the smaller particles dissolve completely and larger particles grow.
Repeated temperature cycling
Bad suspension:
fast to suspend
- slow to redisperse
- deflocculated (forms caking and not redispersibl
Usual Components Of A Pharmaceutical Suspension
Suspending agent
● Dispersing agent
● Wetting agent
● Others (Colorants,flavorants,preservatives)
used for reconstitution of suspensions
Distilled water
These are unique excipients to suspensions! (besides the API and vehicle*
Distilled water
Makes the preparation thicker and this suspends the suspensoid
SUSPENDING AGENTS
Examples
Carboxymethylcellulose (CMC) Methylcellulose microcrystalline cellulose Polyvinylpyrrolidone Xanthan gum Bentonite magma
Employed As Wetting Agents
Alcohol, glycerin and propylene glycol
When an aqueous vehicle is to be used as the dispersion phase.
WETTING AGENTS
Why do we add wetting agents
To avoid clumping of particles
AlOH compressed gel
API
Syrup
Vehicle
Sorbitol solution
Sweetener
Glycerin
Co-solvent
Methylparaben
Propylparaben
Antimicrobial preservatives
Flavor
Flavorant
Purified water, to make
Solvent
