SUPENSIONS
Suspensions
Suspensions are biphasic liquid dosage
form consisting of finely divided solid particles dispersed in liquid medium
with the help of suspending agent.
The requirements/charateristics for a
good suspension
1.
It should be
chemically stable.
2.
The sediment
should be easily re-dispersed.
3.
The suspension
should be easily removed from the container.
4.
The suspension
should be free from large particles.
5.
They should be
resistant to micro – organisms.
6.
Suspension for
internal use must be palatable & suspension for external use should be
force from gritty sealing.
Flocculated & De-flocculated
suspension.
Flocculated suspension:
In flocculating system, when a
suspending agent is added it should be well absorbed, due to the repulsive
forces are low & the attractive forces are high. The individual particles
are able to attract each other & form loose aggregates known as floccules.
This suspension is said to be flocculated.
Deflocculated suspension:
In deflocculated system, when a
suspending agent is added. The individual particles are dispersed with the aid
of suspending agent. Due to the repulsive forces are high & the attractive
forces are low. The individual particles are not able to attract each other. So
the particles remain dispersed & do not aggregate. This suspension is said
to be de-flocculated.
Differences between flocculated
suspensions.
|
Flocculated suspension |
Deflocculated suspension |
|
1. Particles from loose aggregate |
Particles exist in suspension as
separate entity |
|
2. Rate of sedimentation is high |
Rate of sedimentation is low |
|
3. Sediment is formed rapidly |
Sediment is formed slowly |
|
4. The floccules stick to the sides
of the container |
They do not stick to the sides of
the container |
|
5.On shaking the sediment is easily
re- dispersed |
On shaking the sediment is difficult
to re-disperse |
|
6. The suspension has a pleasing
appearance |
The suspension does not have a
pleasing appearance |
 D. Pharm 2nd year PDF Notes){kind=link}
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