We are often asked if parameters used for film coating of 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 Caleva Mini Coater Drier has the unique ability to coat very small sample batch sizes (from a single tablet to about 150 tablets or from a few grams to about 60 grams of pellets) and is typically used for establishing principles of tablet and pellet coating and at a very early stage in the development of new products and new formulations. The following is a real example that demonstrates why the question of “scale up” is not always relevant or important when taking advantage of the benefits of the Mini Coater Drier (MCD).
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 program, he was looking at 8 possible formulations and 10 possible coating materials and wanted to make an initial assessment of the best candidates to carry forward in the development program. He wished to look at all 80 possible combinations of these variables.
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, just a batch of 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. This would require a total sample size of 480 tablets.
However, in this particular case the tablet coater that the scientist had available for use in his laboratory could only work effectively with a minimum batch size of 3 kg.
The choice was:
- to make 80 batches of 6 tablets each with the Caleva MCD (a purchase cost involved)
- or to make 80 batches of 3 kg each with the equipment he had in his laboratory (no additional purchase cost but a significant increase in product handling and cost).
The logistics of coating either 480 tablets or 240 kg 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.
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 0.24 kg of tablets) compared with making 80 samples 3 kg (approximately 240 kg 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 and was not relevant at this stage. It 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 with larger machines developed for this purpose.