Effect Of Magnesium Stearate On A Pharmaceutical Blend Using Thermal Effusivity
Powders are blended together to produce pharmaceutical products and the consistency of those powders is critical to the quality of the product. Typically a blender is charged with four or more individual components and they are blended for a fixed period of time and speed. A fixed blending process does not take into account the variability of the components and this can lead to variation in the product. Despite the fact that a lot of effort has been committed to reduce the lot to lot variability of the components, the industry is still facing the problem that slight variations in the chemical or physical properties of these components can potentially have a huge impact on the final product. Variation of the components could be due to several factors, some of these include: environmental temperature, humidity, feedstock grade, and particle size distribution. To add to the complexity, almost all tabletting materials require lubrication to some degree. Magnesium Stearate is the most widely used lubricant. It is typically added to the blend a few minutes (2-5 minutes) prior to the conclusion of the blending period. Even if it is used in low concentrations (0.2%-1.5%), it is often the cause of many issues experienced with solid oral dosage forms.
What are the most frequent problems?
Determining the amount of lubricant to use and the manner in which it is to be incorporated into a batch is critical. If the concentration is too low, or distribution and mixing time is inadequate, the compression of granules may exhibit punch filming; picking; sticking; capping or binding in the die cavity. If the concentration is too high, or distribution and mixing times are too great, other issues are often encountered including: a decrease in tablet hardness; reduced compressibility of the blend; an increase in tablet disintegration times and/or a decrease in the rate of dissolution may occur.
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