Mixing Time Importance for Blend Uniformity



Mixing time during blending is an important factor. Extended mixing time can affected blend uniformity and pharmaceutical product quality.

In pharmaceutical tablet manufacturing process more than one ingredients are mixed during blending in dry powder blender. Inadequate mixing time could also result in poorly blended mixture. If the mixing time too short, the blend is not mixed properly on the other hand, if the mixing time too long, over mixing occur. Due to over mixing constituents will separate in dependence their differing properties.

Due to increased mixing time blend ingredients can segregate that can cause unequal distribution of pharmaceutical ingredients in dosage unit.

Factors affect on blend uniformity is particle size, density of material and interaction of material due to extended mixing time.

  • Particle size – Material can segregate due to different particle of blend ingredients.
  • Interaction of materials- Interaction between drug and excipients may cause the improper mixing of ingredients.
  • Density of materials – A considerable difference in density of materials being mixed may cause the segregation of material having higher density.

Above three factor works during the blending when vibration occur then smaller particles of material move under bigger particles. Due to this segregate smaller and bigger particles of the same material. If mixing time is extended then higher density material move towards bottom of the blender. It may also cause the separation of different blend ingredients based on their density. So, Blend mixing time is also a important factor to achieve the highest degree of blend uniformity.

Different particles of materials have interaction between them. Interaction can be increased during blending. Particles of two different materials having more interaction may segregate causing the material non-uniformity in the blend.

Therefore, blending process must be done carefully. Validate mixing time should be followed strictly during blending.