Pharmaceutics: Exicipients For Powder Mixtureso Flashcards
What is an excipient?
an inactive substance that serves as the vehicle or medium for a drug or other active substance.
What makes an ideal excipient?
1) Inert - doesn’t react with drug or other excipients
2) Safe - non-toxic, non-allergenic, non-irritant
3) Quality Assured - appropriate purity/grade, performs the same across batch, complies with quality standards.
4) Economical
6 types of excipients?
1) diluent - bulk up the volume
2) binder - makes particles stick
3) disintegrant - disperses particles when in contact with water
4) glidant - helps particles flow past each other
5) anti-adherent - reduce adhesion between stationary powder and equpiment.
6) lubricant - reduce sticking of powder/tablet to equipment
6 common excipients used?
1) Lactose
2) Starch
3) Cellulose
4) Talc
5) Colloidal silicon dioxide
6) Magnesium Stearate
What is Lactose and where is it found?
- Lactose is a sugar found in milk.
- disaccharide of glucose and galactose.
- undergoes the Maillard reaction to produce a yellow-brown colour by reacting with primary amines. So is considered a reducing sugar.
Is lactose water soluble?
yes
problem with using lactose as an excipient?
problematic for lactose-intolerant individuals.
What does it mean when Lactose is GRAS-listed?
It is Generally Regarded As Safe to use!
What type of excipient is lactose monohydrate?
- for tablets and capsules it is a diluent.
- in wet granulation tableting it is a binder.ww
What type of excipient is anhydrous lactose?
Used as a diluent and binder for hard-shell capsules and direct-compression tablets.
Which of the lactose isomers exist more when it’s anyhydrous?
beta-lactose (70-80%)
alpha-lactose (20-30%)
so beta exists more.
What type of excipient is spray-dried lactose?
diluent and binder in direct compression tableting.
Although starch is GRAS-listed, there are still downsides to using it such as?
wheat proteins (gluten) - problematic for celiac disease
Which of the two is generally more in natural starch, amylose or amylopectin?
Amylopectin
What type of excipient is natural starch used as?
- binder
- diluent
- disintegrant
- anti-adherent
- lubricant
(basically all except glidant)
What type of excipient is pregelatinised starch used as?
- binder (better than natural starch)
- diluent
- disintegrant
(used in wet and dry granulation and in direct-compression in tableting)
What is cellulose made of?
D-glucose (beta-glucose)
Where is cellulose found?
In the pulp of fibrous plants
What type of excipient is powdered cellulose used as?
- binder - for hard-shell capsules
- diluent - in tablets
- disintegrant - in tablets
- glidant - in tablets
What type of excipient is microcrystalline cellulose used as?
- binder and diluent - in wet granulation and direct-compression in tableting.
- disintegrant
- anti-adherent
- lubricant
- adsorbent
Problems with using Talc as an excipient?
1) may contain traces of aluminium silicate and iron making it incompatible with quaternary ammonium compounds.
2) purity varies with geographical source and may need purifying (timely and costly
3) may contain asbestos which is a carcinogenic
What type of excipient is talc used as?
- glidant
- lubricant
- anti-adherent
- adsorbent
- dissolution retardant
Why is talc coated on larger particles?
to reduce cohesion. adhesion and friction
Is colloidal silicon dioxide soluble in water?
nope, it forms a colloidal dispersion in water
What type of excipient is colloidal silicon dioxide used as?
- glidant
- tablet disintegrant
- adsorbent
What type of excipient is Magnesium stearate used as?
-lubricant
What three things is magnesium stearate insoluble in?
ethanol, water and ether
How does magnesium stearate accelerate aspirin degradation?
increases aspirin solubility and hydrolysis by elevating the pH.
What three things is magnesium stearate incompatible with?
1) strong oxidising agents
2) Iron salts
3) strong acids and alkalis.
