Northern University Bangladesh
A coarse suspension is a dispersion of finely divided, insoluble
solid particles (the disperse phase) in a fluid (the dispersion
medium or continuous phase).Most pharmaceutical
suspensions consist of an aqueous dispersion medium,
although in some instances it may be an organic or oily liquid.
A disperse phase with a mean particle diameter of up to 1 µm
is usually termed a colloidal dispersion, and
hydroxide and magnesium hydroxide
suspensions. A solid in liquid dispersion, in which the
particles are above colloidal size, is termed a coarse
The product must remain sufficiently
homogenous for at least at the period between shaking the
container and removing the required amount.
Nature of Sedimentation:
The sedimentation or creaming produced
on storage, if any, must be easily
agitation of the container.
Thickness or Viscosity
The product may be required to be
thickened or viscous in order to reduce the rate of settling of the
particles. The resulting viscosity must not be so high that removal
of the product from the container and transfer to the site of
application is difficult.
Any suspended particles should be small and
uniformly sized in order to give a smooth, elegant product, free
from a gritty texture.
Based On General Classes
Based On Proportion Of
Dilute suspension (2
Nature Of Solid Particles
Based On Size Of Solid
Colloidal suspension (< 1
Coarse suspension (>1
∙ Suspension can improve chemical stability of certain
∙ Drug in suspension exhibits higher rate of bioavailability
than other dosage forms.
bioavailability is in following order,
Solution > Suspension > Capsule > Compressed Tablet
> Coated tablet
∙ Duration and onset of action can be controlled.
∙ Suspension can mask the unpleasant/ bitter taste of
and compaction can causes
∙ It is bulky sufficient care must be taken during handling
∙ It is difficult to formulate
∙ Uniform and accurate dose can not be achieved unless
suspension are packed in
unit dosage form
Suspension is usually applicable for drug which is
insoluble or poorly soluble. E.g.
∙ To prevent degradation of drug or to improve
stability of drug.
∙ To mask the taste of bitter of unpleasant drug.
∙ Suspension of drug can be formulated for topical
application e.g. Calamine lotion
∙ Suspension can be formulated for
application in order to control rate of drug
∙ Vaccines as a immunizing agent are often
formulated as suspension.
E.g. Cholera vaccine