Excipients Flashcards
What is the use of saccarin and aspartame in oral formulations?
Sweeteners
What is the degradation product of aspartame?
Phenylalanine - so should not be ingested by patients with the condition phenylketonuria (because they don’t have the enzyme that breaks it down)
A decrease in the number of OH groups in an organic compound increases its sweetness. True or false?
False - an increase in the number of OH groups
Hydrophobic diluents can increase the rate of absorption. True or false?
False - hydrophilic
What is the aim of a diluent (filler)?
To increase bulk of a tablet, especially for low dose potent drugs
How can a diluent increase the rate of dissolution of a poorly soluble drug?
As the diluent is hydrophilic, particles of it will dissolve in the GI fluid, leaving a porous mass of drug where GI fluids are able to penetrate. This way SA and hence dissolution rate is increased
Name a diluent
Mannitol Lactose Sucrose Glucose Sorbitol
How do disintegrants work?
When they come into contact with intestinal fluids, the absorb liquid and start to swell, dissolve and form gels. This causes the tablet structure to rupture and disintegrate, increasing SA and enhanced dissolution of drug
What are the four mechanisms that disintegrants are able to function by?
Wicking
Swelling
Deformation
Repulsion
What is the difference between non-ionic and anionic polymer disintegrants?
Non-ionic are natural or physically modified polysaccharides
Anionic are mainly chemically modified cellulose products or low-crosslinked polyacrylates
PVP is an anionic polymer disintegrant. True or false?
False - non-ionic
Disintegrants don’t have an effect on drug bioavailability. True or false?
False - they are able to regulate bioavailability
What do lubricants do?
They reduce the frictional forces between particles and between particles and metal contact surfaces
How do boundary lubricants work?
Adhere to solid surfaces to reduce friction
How do fluid film lubricants work?
Melt under pressure and create a thin fluid film around particles, but resolidify after pressure is removed
How do liquid lubricants work?
They are released from granules under pressure and create a fluid film. They do not resolidify when pressure is removed but are reabsorbed and redistributed through the tablet matrix
Lubricants are often hydrophilic and aid dissolution. True or false?
False - hydrophobic and retard liquid penetration into the capsule - so reduce dissolution
What is magnesium stearate?
A lubricant
What is a binder?
A binder causes agglomeration of powder into granules during mixing with a granulating fluid, by altering inter-particle adhesion
Which excipient ensures that tablets can be formed with the required mechanical strength?
Binders
Binders can be natural polymers, synthetic polymers or sugars. Name a binder
Sucrose
Starch
PVP
Name a chelator and outline its role
EDTA - forms soluble stable complexes with metal ions, removing the ions from solution and so preventing them from reacting with other elements and/or precipitating
Chelators are only used in oral formulations. True or false?
False - used in oral, parenteral and topical formulations
Name an antioxidant
Sodium sulfate
A buffering agent does not contribute charges to the formulation. True or false?
False - contributes charges, this may affect flocculation behaviour and ionisation state of other components
Parabens are anti-microbial preservatives used in oral formulations. True or false?
False - used in topical and parenteral formulations
Name two anti-microbial preservatives used in oral formulations
sorbic acid
benzoic acid
What is benzalkonium chloride and what is it used it?
Anti-microbial preservative - used in eye drops
Benzalkonium chloride is an anionic surfactant. True or false?
False - cationic
What are viscosity enhancing agents used for?
To ease pouring
Palatability
Slow down rate of sedimentation of dispersed particles
An increase in viscosity leads to a decrease in rate of dissolution. True or false?
True
Viscosity enhancing agents are used to stabilise disperse systems. True or false?
True
Viscosity enhancing agents are colloidal sol particles. True or false?
True
Wetting agents are typically surfactants above their critical micelle concentration. True or false?
False - below their cmc
What is sodium sulifte and in which preparations is it used?
Antioxidant and high pH
What is sodium bisulfite and in which preparations is it used?
Antioxidant used in neutral pH preparations
What is sodium metabisulfite and in which preparations is it used?
Antioxidant used in preparations with a low pH
