What is a Lubricant?
An excipient used in tablet & capsule formulation to reduce friction between powder/granules and the die wall during compression & ejection.
Standard Usage Range & Maximum Limit
Lubricant ,Standard Range (% w/w) , Maximum Limit (% w/w)
Magnesium stearate - 0.25 -1.0 (Max.-1.0%)
Calcium stearate 0.5 – 1.5 (Max.1.5%)
Stearic acid 0.5 – 2.0 (Max. 2.0%)
Talc 1.0 – 5.0. ( Max. 5.0%)
General rule: In most formulations, total lubricant ≤1%, except talc (up to 5%)
Golden Rules of Lubricant Use
🟢 Add Last → Only at the final blending stage.
🟢 Mix Less → Mix gently for 2–5 minutes to prevent over-coating.
Why Not Added During Wet Mixing?
💧 Hydrophobic → Repels binder solution, affects granule formation.
💧 Loses lubricating property → gets washed out during granulation.
💧 Produces weak granules → causes capping, lamination, poor hardness.
Why Not Exceed Maximum Limit?
🔻 Hydrophobic Film Formation → Blocks water penetration → poor disintegration & dissolution.
🔻 Reduced Hardness → Over-lubrication weakens inter-particle bonding.
🔻 Bioavailability Issues → Slower dissolution → therapeutic failure.
🔻 Regulatory Failure → Tablets may not meet pharmacopeial QTPP (Quality Target Product Profile).
Practical Example
👉 In Paracetamol tablets:
Magnesium stearate (0.25–0.5% w/w) is added last, mixed for 2–3 min only.
If used >1% or mixed too long → tablet shows softness, delayed disintegration & dissolution.
Quick Summary
✔️ Lubricant range: 0.25–5% (depending on type).
✔️ Maximum limit: usually ≤1%, except talc (≤5%).
✔️ Golden rule: Add last, Mix less.
✔️ Never in wet mixing: hydrophobic → weak granules.
✔️ Exceeding max limit → poor hardness, disintegration & dissolution.