Mini Coater Drier results - can they be used in the scale up of process development?


Author: Dr Steve Robinson.  steve.robinson@caleva.com

We are often asked if parameters used for coating materials in the Mini Coater Drier can be used for “scale up” to production. The desire for a process to be scalable is understandable but it is not always feasible or relevant. 

The Mini Coater Drier has the unique ability to coat very small samples sizes and is typically used at a very early stage in the development of new products and new formulations. The following is a story that demonstrates other applications and benefits of the Mini Coater Drier (MCD).

Caleva Mini Coater Spray Dryer for the Laboratory

The Real Problem

We recently had an opportunity to demonstrate the MCD in a research laboratory affiliated to a major multinational pharmaceutical manufacturer. 

The scientist in question was working on formulation development with a new experimental active ingredient. As part of his programme he was looking at 8 possible formulations and 10 possible coating materials. He wished to look at all possible combinations of these variables. That is, 80 different combinations!

This situation is probably not uncommon and if the number of variables to be looked at increases only slightly then the possible number of combinations will increase dramatically. 

For these trials, six tablets from each of these combinations were required to do a preliminary dissolution test. 

Using the Caleva Mini Coater Drier six tablets of each combination could be made quickly and easily without any wastage of material. 

However, in this particular case the tablet coater that the scientist had in his laboratory could only work effectively with a minimum batch size of 3 kg.

The Options

The choice was:

  • to make 80 batches of 6 tablets each with the Caleva MCD (a purchase cost involved!);
  • or to make a 80 batches of 3 kg each with the equipment he had in his laboratory (no additional purchase cost).

The logistics of coating either 480 tablets or 240kg of tablets can easily be seen to demonstrate that the Caleva MCD has significant advantages. However there was in this case a much more powerful argument for the purchase of the Caleva MCD.

Tablets spray coated and dried with the Caleva Mini Coater Drier

The Cost Advantage of the Mini coater drier

The active ingredient being tested was a new experimental material and as such was not only expensive but also scarce. In this circumstance it was very easy to do a quick calculation of the cost saving that could be achieved by making 80 samples of six tablets (approximately 0.1kg of tablets) compared with making 80 samples 3 kg (approximately 240kg of tablets!).


In this case it was easy to show that the cost savings that would be made in this single experiment alone would more than pay for the cost of the MCD. This did not take into account the savings in time and effort of using the Caleva MCD and the additional cost savings that would be made in future work with this or other products.

The question of “scale up” never arose. This was irrelevant at this early stage of product development. 

Once the coating parameters of your tablets or pellets are tested and established at laboratory scale then the issues of scale up to production can be subsequently addressed.

If you would like to discuss this in more detail with the author, Dr Steve Robinson, you are more than welcome to do so.  steve.robinson@caleva.com - alternatively ask us about this subject on the contact form on the right of this page.  You may find our online chat useful too.

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