Suspensions Flashcards
Define suspension
Based on what are the suspensions classified
Based on routes of administration
Based on proportion of solid particles
Based on electro-kinetic nature of solid particles
Based on size of solid particles
What is the classification of suspension based on the routes of administration ?
What is the classification of suspension based on the proportion of solid particles ?
What is the classification of suspension based on the electro-kinetic nature of solid particles ?
What is the classification of suspension based on the size of solid particles?
List advantages of suspensions
Overcomes difficulty of swallowing
Faster rate of dissolution and oral absorption
Higher rate of bioavailability
Useful for low solubility drugs
Masks unpleasant taste of drugs in their soluble form
Improves chemical stability
Duration and onset of action can be controlled
List disadvantages of suspensions
What are the properties of good suspension
What is considered during formulation of suspensions
Why it is important to consider particle size for suspensions?
Why is it important to consider particle shape for suspension?
What is zeta potential ?
The difference in potential between the surface of tightly bound layer
What is flocculation
What is the value for zeta potential
+- 30mV
What are the differences between flocculated and deflocculated suspension ?
What are the excipients present in suspensions?
Wetting agents
Suspending agents
Thickening agents
Buffers and pH adjusting agents
Coloring agents
Preservatives
What is wetting agent?
A substance that lowers the surface tension of a liquid and thus allows it to spread more easily
What will happen if there is excessive amount of wetting agent ?
Will lead to foaming or undesirable taste or odor to suspension
What does the wetting ability depend on?
The angle of contact between the particle and the solvent which should be less than 90
Example of wetting agents
Alcohol in tragacanth mucilage
Glycerin or glycol in sodium alginate
What are suspending agents ?
They form film around particle and decrease the inter-particle attraction
What do the surfactants with negative charge do ?
They are absorbed on the particles, minimize flocculation in the presence of positive ions because of natural repulsion of like charges
Example of negative charge surfactant
Sodium lauryl sulphate, sodium dioctyl sulphocinate
Example of non-ionic surfactant
Tweens, carbowaxses
What is thickening agent
They increase the viscosity of the continuous phase so that the particles remain suspended for a sufficient long time
What are the thickening agents rarely used ?
Natural thickening agents - acacia, tragacanth, sodium alginate
What are the thickening agents used commonly ?
Semi-synthetic structured vehicles - methyl cellulose, CMC, hydroxypropyl methyl cellulose
What are other example of thickening agents
Clays such as hydrated aluminium silicate or magnesium silicate
What are the requirements for preservatives ?
What are the examples of preservatives ?
Benzoic acid, sodium benzoate, methyl and propyl paraben
What are the factors affecting stability of suspensions ?
Particle size
Increasing the viscosity
Temperature
The rate of sedimentation, agglomeration is affected by what?
Particle size
What is the most efficient method of producing small particle size ?
Dry milling
Wet milling for potentially explosive ingredients
What will happen to the rate of sedimentation if the viscosity is increased?
The rate of sedimentation will be reduced
What else is dependent on viscosity ?
The rate of release of a drug from suspension
How does temperature affect stability of suspensions?
Temperature fluctuations can lead to caking and claying
What are the methods for stabilizing suspension ?
Electrical stability
Steric stability
What is electrical stability ?
What is steric stability ?
What is the packaging of suspensions?
Wide mouth containers having adequate space above the liquid to ensure proper mixing
Parenteral suspensions are packed in either glass ampules or vials
What are the characteristics for ideal packaging of suspension
What should the labeling of suspension include ?
What conditions should the suspension be stored at ?
What are the recent advances in suspensions ?
Nanosuspensions
Tastebmasked pharmaceutical suspensions
Sustained release suspensions
What are nanosuspensions ?
