35 Questions
What is a suspension?
A liquid system comprising of a solid distributed throughout a liquid
What is the particle size range for colloidal suspension?
Up to 1 µm
Which of these is a reason for using suspensions?
Unpalatable active ingredients
Which active ingredient is mentioned as being insoluble?
Ibuprofen
What particle size range defines a coarse dispersion?
Greater than 1 µm
What characteristic of a well-formulated suspension ensures it has a smooth texture?
Small particle size
Which of the following is important for ensuring a well-formulated suspension can be administered successfully?
Homogeneous during administration
To ensure a suspension is easily pourable, what property should its viscosity have?
Viscosity balanced between high enough to retard sedimentation and low enough to pour
Which of these qualities is essential for a suspension to be re-dispersible?
Easily re-dispersible
What is a key characteristic of well-formulated suspensions that helps retard sedimentation?
High viscosity
Which agent is used to increase the viscosity in indiffusible solid suspensions?
Tragacanth
What is the purpose of grinding particles in a mortar for indiffusible solid suspensions?
To control particle size
Which of the following is a wetting agent used in indiffusible solid suspensions?
Glycerol
What characterizes a deflocculated suspension compared to a flocculated one?
Pleasant appearance and difficult to re-disperse
What is a characteristic of flocculated suspensions?
They form loose aggregates known as floccules
Which agent is used to control the particle size in indiffusible solid suspensions?
Mortar
Which of the following is a thickening agent used to increase viscosity in indiffusible solid suspensions?
Carboxymethylcellulose
What characteristic describes deflocculated suspensions?
Forms a cake once settled
Which of the following is a wetting agent?
Glycerol
What happens to floccules in indiffusible solid suspensions?
They are loose aggregates
What characteristic does a suspension of diffusible solids exhibit?
Easily dispersed in water and re-dispersed after settling
Which type of suspension requires suspending agents?
Suspension of indiffusible solids
Which equipment is used to work out lumps during the manufacture of diffusible solid suspensions?
Mortar and pestle
At what stage are colourants, flavourants, and volatiles typically added in the manufacture of diffusible solid suspensions?
Towards the end
What happens to insoluble solids during the preparation of diffusible solid suspensions?
They are dispersed in a small quantity of the liquid vehicle
What is the first step in the manufacture of an indiffusible suspension?
Insoluble powders and dry suspending agents added to mortar
Which step involves dissolving soluble solids in the vehicle?
Step 4
What is characterized as forming pure clumps and not readily dispersing in water?
Indiffusible powders
Which property is NOT associated with diffusible powders?
Form pure clumps
When are colorants, flavourants, and volatiles added in the manufacture process?
Just prior to making to volume
Which of the following is a natural polysaccharide?
Tragacanth
Which category does Bentonite belong to?
Clays
Which option is a semi-synthetic polysaccharide?
Methylcellulose
Which of these is a synthetic thickener?
Carbomer
What type of suspending agent is Acacia?
Natural polysaccharide
Study Notes
Suspension Defined
- A suspension is a liquid system comprising of a solid (disperse phase) distributed throughout a liquid (continuous phase)
- There are two types of suspensions: colloidal suspension (particle size up to 1 µm) and coarse dispersion (particle size > 1 µm)
Importance of Suspensions
- Insoluble active ingredients (e.g. Ibuprofen) require suspension formulation
- Unstable actives in solution (e.g. Amoxycillin) can be stabilized through suspension
- Unpalatable active ingredients can be masked through suspension
- Suspensions allow control over the rate of release
Characteristics of Well-Formulated Suspensions
- Homogeneous during administration
- Easily re-dispersible
- Optimal viscosity to retard sedimentation and facilitate pouring
- Small particle size for a smooth texture
Types of Suspensions
- Suspension of diffusible solids: easily wetted by water, mixes readily, and stays dispersed long enough to administer a dose
- Suspension of indiffusible solids: does not disperse readily in water, forms porous clumps, and requires suspending agents
Method of Manufacture (Diffusible)
- Disperse solids in a small quantity of liquid vehicle
- Work out lumps using a mortar and pestle
- Dissolve soluble solids in the vehicle and add
- Add colourants, flavourants, and volatiles towards the end
Formulation of Indiffusible Solid Suspensions
- Control particle size by grinding in a mortar
- Use thickening agents to increase viscosity (e.g. Tragacanth, Carboxymethylcellulose)
- Use wetting agents (e.g. Glycerol, Propylene glycol)
Flocculation
- Floccules are loose aggregates with a high settling rate, but are easily re-dispersed
- Deflocculated suspensions have a pleasant appearance but form a cake that is difficult to re-disperse
- Many suspending agents flocculate to an extent
Suspending Agents
- Natural polysaccharides (e.g. Tragacanth, Acacia)
- Semi-synthetic polysaccharides (e.g. Methylcellulose)
- Clays (e.g. Bentonite, Magnesium aluminum silicate)
- Synthetic thickeners (e.g. Carbomer, Colloidal silicon dioxide)
Learn about suspensions, a type of liquid system used in pharmaceuticals, including types of suspensions and their importance in drug development.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
