Excipients Flashcards
What is an excipient?
An additive that has no therapeutic effect
What are the purposes of an excipient?
Enhancement of: Delivery Acceptability Stability Handling
What are the ideal properties of an excipient?
Inert
Safe- Non-toxic
Quality-assured-: Appropriate purity or grade, compliance to BP standards
Economical
Excipients for powder mixtures
Dilutent- increases bulk of tablet
Binder- helps particles to stick
Disintegrant- breaks up tablet into granules (H20)
Glidant- enhances powder flow
Anti-adherent- Prevent powders sticking to surfaces
Lubricant- Reduces friction
What are the 6 excipients?
Lactose Starch Cellulose Talc Colloidal silicon dioxide Magnesium Stearate
What are the subtypes of excipients?
Monohydrate anhydrous spray-dried Natural pre-gelatinised powder crystalliine
What is lactose?
Is it water-soluble?
Glucose and galactose
Water-soluble
GRAS-listed (regarded as safe)
Maillard reaction: instability with amine containing drugs
What are the different forms of lactose?
Lactose monohydrate
Anhydrous lactose
Spray dried lactose
What are the difference in the sub types?
The preparation of the excipients
What is lactose monohydrate?
Crystallised from superunsaturated lactose solutions
Odourless, white
What is lactose monohydrateprimarily used as?
Dilutent for tablets and capsules
Binder for wet granualtion in tabletting
How do you prepare anhydrous lactose?
Dry the lactose solution, then reduce the powder and crush it
What is anhydrous lactose primarily used as?
Dilutent and binder for hard-shell capsules
Direct compression tablets
What does granualtion mean?
Aggregate the powders to form larger clumps
How is spray-dried lactose prepared?
By spray-drying lactose solution
Start as liquid droplets, then solidify into spherical particles (high compactibility)
What is spray-dried lactose used as?
Dilutent
Binder
Direct-compression tableting
What is starch?
Made up of amylose and amylopectin
What are the two types of starch?
Natural
Pregelatinised
What protein does starch contain?
Wheat protein
What does starch naturally exist as?
Starch granules
1) Corn starch
2) Pea starch
What are the properties of Natural starch?
Odourless
Tasteless
White
Fine powder
What is natural starch primarily used as?
Binder Dilutent Disintegrant Anti-adherent Lubricant
What are the properties of pregelatinised starch?
Odourless
Slight characterstic taste
White
Fine powder
What is pregelatinised starch primarily used as?
Binder- better binder properties due to fluffiness (cohesion with partciles)
Dilutent
Disintegrant
What types of granualtion is pregelatinised starch used in?
Wet granualtion
Dry granulation
Direct-compression
What are the two types of cellulose?
Powdered cellulose and Microcrystalline cellulose
What type of glycosidic bond does cellulose have?
B-1,4 glycosidic bond
How is cellulose obtained?
From the pulp of a fibrous plant
Which agent is cellulose incompatible with?
Strong oxidising agent
What groups are good binders and good dilutents?
Polysaccharides/saccharides
What is powdered cellulose primarily used as?
Dilutent - hard-shell capsules
Binder
Disintegrant
Glidant
What is the E number of cellulose?
E460
What is microcrystalline cellulose?
Modified form of natural cellulose
What are the properties of microcrystalline cellulose?
Porous Hygroscopic Crsytalline White Odourless Tasteless
How is microcrystalline cellulose prepared?
Partially depolymerised cellulose obtained through controlled acid hydrolysis then spray-dried
What is a good substitue for lactose for a filler?
Microcrystalline cellulose
What makes a good disintegrant?
Things that swell in water
What is talcum powder alrgely used as?
Used as a lubricant largely
What is talcum powder
A hydrous magnesium silicate
How is Talc prepared?
Mineral–mined, pulverised and purified
Why do we need to purify substances?
It may contain asbestos which is carciogenic
What are the primary traits of lubricants and glidants?
High specific surface area
What is Talc primarily used as?
Glidant
Anti-adherent
Lubricant
Dissolution retardant
Is Talc water-soluble?
No, it would prevent lactose from dissolving in water if it was water soluble.
What are the properties of Talc?
Odourless
White
Crystalline powder
What does Talc do to larger particles?
Coats them to reduce cohesion, adhesion and friction
What is Colloidal silicon dioxide?
Major component in glass
What are the properties of Colloidal SO2?
Odourless
Tasteless
White/bluish powder
What makes it particlulary effective?
Has a very high specific surface area and is insoluble in water
How is Colloidal SO2 prepared?
By flame pyrolysis of chlorosilanes (forms agglomerates throughout process), in hydrogen-oxygen flame
What is Colloidal SO2 primarily used as?
Glidant
Disintegrant
Adsorbent
What is Magnesium stearate?
Fatty acid with a VV high specific surface area?
What is Magnesium stearate primarily used as?
Lubricant (to reduce friction)
What are the physical properties of Magnesium stearate?
Greasy to the touch
Faint odour
Taste of stearic acid
What is the solubility of Magnesium stearate?
Insoluble in water, ehtanol and ether (due to fatty acid group)
Which agents is Magnesium stearate incompatible with?
Strong oxidising agents, including strong acids and alkalis, iron salt
How does it accelerate aspirin degradation?
Increasing solubility and hydrolysis by elevating pH.
