Excipients for Powder Mixtures Flashcards
What excipients are used for delivery?
Solvent
Co-solvent
Disintegrant
What excipients are used for acceptability?
Colour
Falvourant
What excipients are used for stability?
Antioxidant
Preservative
Suspending agents
What excipients are used for handling (+ vol)?
Filer/diluent
Glidant
Lubricant
What must excipient properties be?
Inert
Safe (non-toxic)
Economical
Quality–assured
What are the excipients for powder mixtures?
Diluent
Binder
Disintegrant
Glidant
Anti-adherent
Lubricant
What are the most common excipients?
Lactose
Starch
Cellulose
Talc
Colloidal silicon dioxide
Magnesium stearate
What are the different types of lactose?
Monohydrate
Anhydrous
Spray-dried
What are the different types of starch?
Natural
Pre-gelatinised
What are the different types of cellulose?
Powdered
Microcrystalline
Describe lactose
H2O soluble
Less sweet than sucrose
What are the 2 isomers of lactose?
α-lactose
β-lactose.
What are the problems with lactose?
Instability with primary amine-containing drugs.
Problematic for lactose-intolerant individuals.
Describe lactose monohydrate
H2O content higher than lactose
Odourless
White
How is lactose monohydrate formed?
Crystallised from supersaturated lactose solutions
Crystal shapes depend on method of precipitation
What is lactose monohydrate widely used as?
Binder with wet granulation in tabletting
OR
Binder for tablets + capsules
What do you not use lactose monohydrate with?
Drugs susceptible to hydrolysis
How is anhydrous lactose produced?
Drying lactose solution, followed by milling + sieving
What is anhydrous lactose used as?
Diluent + binder for tablets + hard-shell capsules
What is anhydrous lactose suitable for?
Moisture-sensitive drugs.
Describe spray-dried lactose
Mixture of α-lactose monohydrate and amorphous lactose
How is spray-dried lactose produced?
Spray-drying lactose solution
Why is it good that spray-dried lactose has spherical particles?
High compactability
What is spray-dried lactose primarily used as?
Diluent and binder in direct compression tableting.
Describe starch
Extracted from food crops
Amylose + amylopectin
What is problem with starch?
Celiac disease
Describe natural starch
Polysaccharide of D-glucose
α-1,4-glycosidic bonds
More amylopectin (branched) than amylose
What is natural starch primarily used as?
Binder, diluent + disintegrant
Describe natural starch powder
Odourless, tasteless, white, fine powder
How is pregelantised starch formed?
Granules ruptured chemically at mechanically at 62-72°C
Describe pregelatinised starch
Odourless, white powder with slight characteristic taste
What is pregelatinised starch used as?
Binder, diluent + disintegrant
What is better about pregelatinised starch than natural?
Improved binder properties
Describe cellulose
Polysaccharide of D-glucose linked with β-1,4-glycosidic bonds
Obtained from pulp of fibrous plants
How is powdered cellulose obtained?
Obtained by mechanical particle size reduction of pulp
Describe powdered cellulose
White, odourless, tasteless
Slightly hygroscopic
What is special about powdered cellulose?
Wide range of particle sizes ranging from fine to coarse, free flowing to non-flowing, dense or fluffy
What is powdered cellulose primarily used as?
Diluent for hard-shell capsules
Describe microcrystalline cellulose
Porous, hygroscopic, crystalline
White, odourless, tasteless
How is microcrystalline cellulose obtained?
Through controlled acid-hydrolysis and spray-dried
What is microcrystalline cellulose primarily used as?
Diluent + binder in wet granulation + direct compression
Describe talc
Hydrous magnesium silicate
May contain traces of aluminium silicate and iron
How is talc obtained?
Mineral—mined, pulverised and purified
What must talc be free from?
Asbestos (carcinogenic)
Iron
What is talc primarily used as?
Glidant, anti-adherent + lubricant
What does talc do?
Coats larger particles to reduce cohesion, adhesion and friction
What is talc insoluble in?
Dilute acids and alkalis, organic solvents and water
What is asbestos-free talc considered?
Non-toxic, not absorbed orally
What is talc incompatible with?
Quaternary ammonium compounds
Describe colloidal silicon dioxide
Odourless, tasteless, white/bluish-white powder
What is colloidal silicon dioxide insoluble in?
Practically H2O and organic solvents
What does colloidal silicon dioxide form in H2O?
Forms colloidal dispersion
What is colloidal silicon dioxide used as?
Glidant
= coats larger particles to reduce cohesion
How is colloidal silica dioxide formed?
Prepared by flame pyrolysis of chlorosilanes in hydrogen-oxygen flame at 1800°C, then cooled rapidly
Describe magnesium stearate
Greasy to the touch, cohesive and adherent
Faint odour and taste of stearic acid
Hydrophobic
What is magnesium stearate practically insoluble in?
Ethanol, ether + water
What is magnesium stearate incompatible with?
Strong oxidising agents
What can magnesium stearate cause?
Aspirin degradation
= increases solubility + hydrolysis by elevating pH
What is magnesium stearate primarily used as?
Lubricant