Lecture 6- Tableting I Flashcards
Tablet production
-powders intended for compression into tablets must possess 3 essential characteristics;
*powder flowability
- material can be transported through the hopper into the die to produce tablets of consistent weight and drug dose
- powder flow can be improved= glidant/ granulation
*powder compressibility
- ability of powder to deform under pressure
*powder compactibility
- the property of forming a stable, intact compact mass when pressure is applied
Tablet manufacturing
- direct compression, wet/dry granulation
^choice of method depends on;
-size of dose, flowability of drug, compressibility, compactibility and stability characteristics of the drug
Starting point; dose of drug
*low dose (<25mg)
-most of the tablet will be excipients; check content uniformity
*high dose (>250mg)
-most of the tablet will be drug; check compactibility + flowability
Lower dose drugs can be directly compressed
Blend —> compress
-can compensate for any lack of compactibility/ lack of flowability by the use of special direct compression fillers
-can provide lubricity by addition of die wall lubricant
-can help fluidity by adding a glidant
-assure rapid disintegration by adding disintegrant
General formula for a direct compression tablet
Drug = 1 part
Filler-Binder = 3 parts
➤ Mix of materials that help the tablet hold shape (plastic & brittle types, ratio 3:1)
Disintegrant (10–20%)
➤ Helps the tablet break apart in the body
➤ Examples: Starch 1500, Ac-Di-Sol, Explotab, Crospovidone
Glidant (0.2–0.5%)
➤ Improves powder flow
➤ Example: Colloidal silica
Lubricant (0.5–1%)
➤ Stops sticking during tablet-making
➤ Example: Magnesium stearate
➤ Add last and don’t overmix! (~5 mins only)
Blend → Sieve → Blend → Add lubricant → Short blend again
Advantages of direct compression
*economical = less time, space, materials, personnel, fewer steps
- elimination of heat + moisture of wet granulation = increased stability
*increased particle dissolution rate
*batch-to-batch variation is negligible
*fewer excipients= less chance of chemical interaction between drug + excipients
Disadvantages of direct compression
-problem of content uniformity for low dose drugs
-segregation of low dose drugs
-drug is fluffy= poor flow and compression
-small-medium dose drugs difficult to tablet due to small final weight
-requires tight control over physical properties of filler-binder
Cost- fillers are more expensive when used in granulation
-punch wear
-dustiness
-static electricity
Requirements for a directly compressible filler
-good flowability
-good blending properties
-low lubricant sensitivity
-high compactibility
-inertness
-constant quality
-relatively cost effective
Examples of direct compression filler-binders
*microcrystalline cellulose
-most compressible/compactable material available
-tablets self disintegrate and require little lubricant
*spray processed lactose
-mini granulation of lactose crystals glued together by small amount amorphous lactose
Direct compression- not practical
-large dose, poorly compressible/compactable
Granulate;
-improves flowability
-addition of a binder = glues the particles together into granules to hold the tablet together = improves compactibility
Wet granulation/ dry granulation
