Calcium stearate is a fine, white to yellowish-white, bulky powder with a slight fatty odor. It is insoluble in water, has a soft texture, and melts at around 149–160 °C. Commonly used as a lubricant, it is composed mainly of calcium salts of stearic and palmitic acids.
Chemical Name and CAS Registry Number :-Octadecanoic acid calcium salt [1592-23-0]
Functional Category :-Tablet and capsule lubricant
| Test | JP 2001 | PhEur 2005 | USPNF 23 |
|---|---|---|---|
| Identification | ✔✔ | ✔ | — |
| Characters | ✔ | ✔ | — |
| Microbial Limit | — | ≤10³/g | — |
| Acidity/Alkalinity | — | ✔ | — |
| Loss on Drying | ≤4.0% | ≤6.0% | ≤4.0% |
| Arsenic | ≤2 ppm | — | — |
| Heavy Metals | ≤20 ppm | — | ≤10 mg/g |
| Chlorides | — | ≤0.1% | — |
| Sulfates | — | ≤0.3% | — |
| Cadmium, Lead, Nickel | — | Specified | — |
| Organic Volatile Impurities | — | — | ✔ |
| Assay (as CaO) | — | — | 9.0–10.5% |
| Assay (as Ca) | 6.4–7.1% | 6.4–7.4% | — |
Calcium stearate is used as a lubricant in tablets and capsules at up to 1% w/w. It also acts as an
emulsifier, stabilizer, and suspending agent in various pharmaceutical, food, and cosmetic products.
Despite its good lubricating properties, it exhibits poor glidant behavior.
Calcium stearate is thermally reactive, softening between 120–130 °C and forming a viscous state at ~160 °C.
At ~100 °C, it loses around 3% of weight due to water of crystallization, causing structural changes in its crystalline lattice.
These transitions impact its behavior in heated formulations. It’s considered nontoxic and is listed in the FCC and various pharmacopeias.
For further detail and comparison, refer to Magnesium Stearate. Its EINECS number is 216-472-8.
