Tablets Flashcards
What are disadvantages of tablets
- Poor bioavailability of poorly soluble drugs (class 4)
- compression can change the physical properties, particle size & crystal form
Explain Class 1 drugs
strategies to improve?
Example
High solubility, High permeability
Immediate-release
Choloroquine diphosphate
Explain Class 2 drugs
strategies to improve?
Example
Low solubility, High permeability
Particle size reduction, salt formation, solid dispersions, complexation, lipid formulations
Ibuprofen
Explain Class 3 drugs
strategies to improve?
Example
High solubility, Low permeability
permeation, enhancers, prodrugs, bioadhesives
Captopril
Explain Class 4 drugs
strategies to improve?
Example
Low solubility, Low permeability
Combination of methods or not feasible for oral, use IV administration
Furosemide
What is considered a highly permeable drug?
Highly soluble?
Highly permeable: absorption over 90% of dose
Highly soluble: when highest dose strength is soluble in 250mL or less at 37 degrees pH 1-7
When are Multiple Compressed Tablets used MCT
when separation of API is needed for stability purposes
- mixing process is inadequate to guranatee uniform distribution of 2+ API
What type of tablets do not need to add a disintegrant
chewable tablets
Explain the sublingual tablets
Rapid systemic effect
bypass first-pass effect (pass by liver)
Differentiate between Group 1 and 2 excipients
Group 1: for processing and compression characteristics
- diluents/filler
- binders
- glidants
- lubricants
Group 2: give physical characteristics
- disintegrant
- surfactants
- colours
- flavours
- sweetening agents
- polymers
What are the roles of binders?
-give cohesive qualities to the powder material
- ensures the tablet remains intact after compression
What are 2 the types of binders?
Solution binders: added as the granulation fluid, more effective
Dry binders: added before wet ingredients or mixed with other ingredients before compaction
(see onenote for examples)
What are the role of lubricants in tablets?
Examples of insoluble & soluble
- prevent adhesion of the tablet to the surface of the dies and punches
- Facilitate the ejection of the tablets from the die cavity
Insoluble:
- magnesium/calcium stearate
- Stearic acid
- Light mineral oil
Soluble:
- Sodium benzoate
- PEG 4000 & 6000
- Sodium lauryl sulfate
Which types of lubricants are the most effective and when are they added?
Insoluble (hydrophobic stearates)
- added last after all components mixed
What does too much lubricant do to drug dissolution?
Lowers
What does the least % concentration of lubricant have effect on drug absorption?
High plasma drug level
What are the roles of glidants?
Examples?
improves flow characteristics by reducing interparticle friction
Ex.
- Colloidal silicon dioxide (Aerosil)
- talc
- Calcium silicate
- Magnesium carbonate
What are the roles of disintegrants?
A substance added to a tablet to facilitate its breakup after administration
What type of tablets don’t have disintegrants?
chewable tablets
What are mechanisms of disintegrants? (3)
Give examples
- Facilitated water uptake (bring liquids into pores of tablets)
ex. starch (5-10%), microcrystalline cellulose, crospovidine - Swelling on contact with water (super-disintegrants)
Ex. sodium starch glycolate, croscarmellose) - Gas production in effervescent tablets
Role of colouring agents?
When can it be added? best?
Role:
- product identification
- Acceptable appearance
Added
- during the coating step (BEST)
- by adding to the formulation
Benefits of granulation
- prevent powder segregation
- improve flow properties
- improve compression
- Reduce dust
- Reduce clumping of hygroscopic powders
Explain wet granulation
Connective mixing using a high-shear mixer
Explain dry granulation
- “slugging” preparation of large tablet which is then milled
- roller compaction - powder is pressed between rollers then ground
