The document discusses pharmaceutical suspensions, defining them as biphasic coarse dispersions with an internal phase of insoluble solid particles dispersed in an external phase. It outlines the reasons for formulating suspensions, criteria for a good suspension, and discusses various types of suspensions based on administration routes and solid particle characteristics. Additionally, it covers the role of suspending agents, wetting agents, and preservatives, along with preparation methods and evaluation techniques.

1. SUSPENSION
Submitted by
C.Sangavi M.Pharm.,
Assistant Professor
Department of Pharmaceutics
Acharya and BM Reddy College of Pharmacy
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2. Definition
 A Pharmaceutical Suspension is a biphasic coarse
dispersion in which internal phase (therapeutically
active ingredient) is dispersed uniformly throughout the
external phase.
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3. INTERNAL PHASE
 The internal phase consists of insoluble solid
particles having a range of size (0.5 to 5 microns)
which is maintained uniformly throughout the
suspending vehicle with aid of single or combination
of suspending agents
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4. EXTERNAL
PHASE
The external phase (suspending medium) is generally
aqueous in some instance, may be organic or oily liquid for
non oral use.
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5. Reasons for the
formulation of
pharmaceutical
suspensions
When the drug is insoluble in the
delivery vehicle
To mask the bitter taste of the drug.
To increase the drug stability.
To achieve controlled/sustained drug
release
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6. CRITERIA FOR
GOOD
SUSPENSION
A Well
formulated
suspension
should
have :
Easy and readily redispersion of sedimented
particles, important for uniformity of dose.
No cake formation on setting.
Viscosity optimum for pouring.
Physical, chemical and microbiological
stability
Pleasing odour, colour and palatability.
Free from gritting particles (in case of
suspension for external use).
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7. Some phramaceutical Suspension
Antacid Oral suspension
Antibacterial oral suspension
Dry powders for oral suspensions (antibiotic)
Analgesic oral suspension
Anthelmintic oral suspension
Anticonvulsant oral suspension
Antifungal oral suspension
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8. CLASSIFICATION OF SUSPENSION
Route of administration
• Oral Suspension
• External application
• Parenteral Suspension
Solid Particle proportion
• Dilute Suspension
• Concentrated Suspension
Solid Particle Size
• Colloidal Suspension
• Coarse Suspension
• Nano Suspension
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9. Based on Solid Particles Electrokinetic Nature
Flocculated Suspension
 Particles forms loose aggregates and form
flocs.
 Rate of sedimentation is high.
 Sediment is formed rapidly.
 The sediment is easy to redisperse.
Deflocculated Suspension
 Particles exist as separate entities form a
cake.
 Rate of sedimentation is slow.
 Sediment is formed slowly.
 A hard cake is formed which is difficult.
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10. SUSPENDING
AGENTS
It increase the Viscosity of the
continuous phase
Minimize the sedimentation
Reduce the Surface tension of the
Solid particles
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11. WETTING AGENTS
Reduce the surface tension between the
solid particles and the liquid medium
Improve the wetting power of the
insoluble substances
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12. FLOCCULATING AGENT
To improve the
dispersibility of
insoluble solid particles.
Example : Sodium lauryl
sulphate, Tween, Span,
Carbowaxes.
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13. PRESERVATIVES
 To preserve the suspension from the
bacterial growth.
 Example : Benzoic acid, Sodium
benzoate, Methyl paraben, Propyl
paraben
ORGANOLEPTIC ADDITIVES
 To enhance the patient acceptability.
 To mask the unpleasant taste.
 To enhance the appearance of the
preparation.
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14. Preparation of the
Suspension
 Two main methods for the formulation of
suspension:
 PRECIPITATION METHODS
 DISPERSION METHODS
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15. PRECIPITATION METHODS
 Three main methods are
• Organic solvent preparation
• Precipitation effected by the change pH of the medium
• Double decomposition
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16. ORGANIC SOLVENT PRECIPITATION
Water insoluble Drugs
Dissolve in organic solvents
Add organic phase to water to form precipitation
 Example : Ethanol, Methanol, Propylene glycol and PEG
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17. PRECIPITATION EFFECTED BY CHANGING PH
 Applicable to those drugs in which solubility is dependent on pH value.
Concentrated solution in favorable pH
Pour to other system to change pH
On agitation precipitation will form
Example : Estradiol suspension
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18. BY DOUBLE DECOMPOSITION
 Two water soluble reagent forms a water insoluble product.
 Example : White lotion NF
Zinc sulphate solution
Solution of sulphurated potash
Precipitate of zinc polysulphide
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19. DISPERSION METHOD
Vehicle is formulated
Solid phase is wetted and dispersed
Use of surfactant to ensure wetting of hydrophobic solids
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20. EVALUATION OF SUSPENSION 20
Sedimentation
Method
Rheological
Method
Electrokinetic
Method

21. SEDIMENTATION
METHOD
 Sedimentation Volume(Sv) is defined as the ratio of the
ultimate height of the sediment(Hu) after settling the
suspension to the full height of suspension(Ho) before
settling.
Sv = Hu / Ho
Where,
Hu = Ultimate height of the sediment
Ho = Full height of the suspension before settling
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22. RHEOLOGICAL METHOD
 It provide information about settling behaviour.
 Brookfield Viscometer is used to study the viscosity of the suspension.
 If the rate of settling of the particles is less, the stability of the suspension is more.
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23. 23
ELECTROKINETIC
METHOD
 Measurement of zeta potential using Micro
electrophoresis apparatus & Zeta Plus.
 It shows the stability of the disperse system
 Two types of electrical potential contribute to
electrokinetic properties.
• Zeta Potential
• Nernst Potential

24. MICROMERITIC
METHOD
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 Stability of suspension depends upon the
particle size of the dispersed phase.
 Any change in particle size with
reference to time will provide useful
information regarding stability of the
suspension.

25. THANK YOU
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