ED 3 Flashcards
Define ‘Solutions’
Homogenous liquid preparations containing one or
more dissolved substances
What factors should be considered when preparing a solution ?
- Solubility of solid constituents
- Which solvents to use ?
- Temperature
- pH (affects stability of final product)
- Colourings, flavourings and preservatives
During preparation of a solution, in what order do you add the soluble ingredients ?
Ascending order (least to most soluble)
Define ‘Suspensions’
Preparations where one or more active constituent is suspended in the disperse phase
Some formulas may or may not contain suspending agents. TRUE or FALSE
TRUE
Why is it important for non-soluble constituents to be re-suspended for long enough ?
Allows patient to measure an accurate dose
Give for examples of Suspending agents
1) Tragacanth BP
2) Compound Tragacanth Powder BP
3) Xanthan gum
4) Methylcellulose
What is Compound Tragacanth Powder BP made out of ?
- Acacia BP 20%
- Tragacanth BP 15%
- Starch BP 20%
- Sucrose BP 45%
About how many %w/v Tragacanth BP is used in suspensions ?
0.2%
About how many %w/v Compound Tragacanth Powder BP is used in suspensions ?
2%
Compound Tragacanth Powder BP is said to be too sticky for external products. TRUE or FALSE
TRUE
About how many %w/v Xanthan gum is used in suspensions ?
2%
About how many %w/v Methylcellulose is used in suspensions ?
b/wn 0.5 - 2%
Is Xanthan gum highly soluble in hot or cold water ?
Cold water
Methylcellulose is a semi-synthetic polysaccharide. TRUE or FALSE
TRUE
Name 4 other types of suspending agents
1) Guar gum
2) Sodium alginate
3) Hydromethylcellulose
4) Sodium carboxymethylcellulose
How many weeks expiry do ‘Freshly prepared’ solutions and suspensions have ?
Two weeks
How many weeks expiry do ‘Recently prepared’ solutions and suspensions have ?
4 weeks
When should ‘freshly prepared’ solutions and suspensions be prepared ? (according to BP 2018 recommendations)
‘No more than 24 hrs before it is issued for use’
When is deterioration likely to occur for ‘recently prepared’ solns and suspensions ? (According to BP 2018 recommendations) ?
Likely to occur if preparation is stored for longer than 4 weeks at 15 - 25 degrees celcius
Define ‘Trituration’
- Incorporation of finely divided insoluble powders or liquids into a base
Define ‘Levigation’
- Incorporation of coarse insoluble powders into a base
Define ‘Fusion’
- Melting of bases before the addition of other ingredients
During ‘Fusion’ process, why does the melting points of ingredients need to be known ?
Because you start with the ingredient with the highest melting point
What is the standard expiry for Creams and Ointments
3 months from date of manufacture
Why do creams/ointments have a long expiry ?
Because the cream/ointment bases contain
preservatives in their formulae
What is the expiry for Diluted creams ?
1 month from date of manufacture
Why do diluted creams have shorter expiry ?
Because creams are generally diluted with aqueous
cream and the aqueous environment is more susceptible to bacterial growth
Do diluted ointments also have a shorter expiry like that of diluted creams ?. YES or NO
NO
