What Are The Effects Of The Particle Size

In the classification of medicines, solid preparations are a very important part and the most familiar type in our lives. In the preparation process, the addition of "excipients" is indispensable. They can play their role in shaping and ensuring quality in the preparation. Among them, although not very eye-catching, lubricants are actually incompatible. Underestimate the influence.

For example, in the operations of mixing, rolling (dry granulation), tableting and capsule filling, lubrication is essential to reduce the friction between the surface of the manufacturing equipment and the surface of organic solids and to ensure the continuity of the operation. Moreover, lubricants only need a small amount of addition (usually 0.25%-5.0%) to achieve significant results. As far as powder flow is concerned, it can also improve the fluidity of the mixture and help unit operations.

In the actual production of medicines, many failures are actually caused by lubrication-related problems. Unfortunately, lubricants have not received enough attention in the development of pharmaceutical preparations. In fact, the powder characteristics of the lubricant have a great influence on the performance of the lubricant formulation, including the mechanical properties of the tablet, the dissolution of the tablet and the flowability of the powder. Therefore, if we study this point, we will be able to better improve the quality of solid preparations. For a lubricant, the most important powder characteristic is its particle size. Let's take a look at this point and see how particle size affects the performance of the lubricant.

Influence of particle size on lubricant performance

Regarding the particle size distribution, the researchers found that reducing the size of the lubricant particles can produce greater cohesion between the particles, thereby increasing the porosity of the tablet. The increase in porosity will rearrange the powder particles and increase the surface area-the larger the specific surface area, the easier it is to be evenly distributed during the mixing process, so the interaction between the particles is strengthened, and finally the tablet strength is significantly improved.

One of the most commonly used lubricants for tablets: magnesium stearate

Although the reduction of powder particle size can bring certain advantages, it will also cause additional undesirable fine particles to be mixed into the formulation relay and cause adhesion. The contamination of these particles will form an unnecessary additional film on the inner surface of the mold wall, and adhesion will cause the compressed tablet to stay in the mold and cannot be ejected. Therefore, the operator must pay attention to its particle size fraction to obtain the required tablet hardness. 

In a recent study, some researchers investigated the effect of different particle size and concentration of magnesium stearate lubricant on tablet performance, and found that if you want to achieve the best tablet hardness (about 18 kPa), stearic acid The concentration of magnesium must be controlled well. In addition, the researchers also concluded that maintaining the optimal particle size can prevent particle separation, reduce weight changes during compression, and improve the hardness and aesthetics of the final product.