Pharmacopeial Specifications
| Test | PhEur 2005 | USP 28 |
|---|---|---|
| Identification | ✔ | ✔ |
| Acid value | 195–210 | — |
| Assay (Zn / ZnO) | 10.0–12.0% Zn | 12.5–14.0% ZnO |
| Heavy metals (Pb, Cd) | ≤25 ppm, ≤5 ppm | ≤0.001% (Pb) |
| Organic volatile impurities | — | ✔ |
Applications in Pharmaceutical Formulation or Technology
Zinc stearate is used in concentrations of 0.5–1.5% as a lubricant in tablet and capsule production. It is also employed as a thickening and opacifying agent in creams and ointments and was once used in baby powders (now discontinued due to inhalation risks).
Comment
Zinc stearate, though effective as a lubricant, must be handled with care to avoid inhalation. It shares functional and chemical characteristics with magnesium and calcium stearates. The EINECS number is 209-151-9.
