Magnesium stearate (MgSt) is often the lubricant of choice in pharmaceutical production. But caution, intensive mixing with MgSt, especially with to high amounts of it, can quickly lead to hydrophobic layers around the granulates, thus affecting the binding forces between them. And when it comes to tableting this will decrease the mechanical strength of the tablets.
The challenge?
To find the perfect balance to prevent issues during ejection and ensuring the right product quality.
An effective approach is to measure the ejection force in relation to the MgSt concentration. This is exemplified in the graph. Typically, the ejection force significantly decreases with increasing MgSt concentration until it reaches a constant level. This point marks the lower limit for the MgSt concentration, unless there's no restriction due to tablet strength. To account for variations in particle size distribution after granulation, we recommend to slightly increase the concentration as a precaution.
Nonetheless, the risk of over-lubrication remains. This should be considered when scaling up to production.
Read also:
- Frequently Used Excipients in Pharmaceutical Formulation
- Sticking and Picking | Tablet Problems and Remedies
