Page 25 - Pharmaceutics III_ 02-06-01304_Fall 2025_ Pharm D_Electronic book

(a) Hydrophobic lubricants (<1% in the formulation)
• Metallic stearate (Mg, Ca, Zn)
• Stearic acid
• Waxes
• Hydrogenated vegetable oil or Sterotex
• Talc (5% in the formulation)

(b) Hydrophilic lubricants
Used only in water-soluble tablets such as effervescent tablets. Examples:

• PEG 4000–6000
• Magnesium lauryl sulfate
Notes
• Lubricants should be finely divided powder and added to the powder by sieving, then

mixed gently for 2–3 minutes to distribute evenly.
• Excess lubricant or over-mixing can adversely affect dissolution rate and prolong

disintegration time because most lubricants are hydrophobic.
• Lubricants must be compatible with the drug.
Example: Aspirin + Mg stearate → promotes decomposition (hydrolysis) to salicylic acid due to
slight alkalinity.
Solution: Use stearic acid or waxes as lubricant instead.

I-3-b. Glidants
Glidants are substances added to improve the flow properties of the granules.
They act by reducing inter-particulate friction through smoothing the surface of the particles.
Types of glidants

1. Colloidal silicone dioxide (0.2–5%) — also called Cab-o-sil or Aerosil (preferred).
2. Starch (5%)
3. Talc (5%)
Method of addition
Added with the lubricant.

II-1. Disintegrants
Substances added to tablets to facilitate breakup or disintegration after administration.
The disintegration increases the surface area, thereby enhancing the dissolution rate.

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