Tablet capping and lamination are two most common defects which are observed during the tablet compression process.The first solution to resolve these issues is to reduce the tablet hardness & compression machine speed but what to do next if the tablet capping and lamination issues are not resolved by reducing the speed of tablet compression machine.
To understand the answer of this question now let’s have a look over the main causative factor of tablet capping and lamination.
Tablet capping and lamination defects are caused by the less moisture content which occurs due to the over-drying defect meaning we dry the granules for prolonged periods and the required level of LOD is not maintained in the granules so it will result in tablet capping and lamination.
Now the simple solution to overcome tablet capping and lamination defects is to apply the moisture or moisten the granules.
How to apply moisture?
When a batch is already granulated how to apply the moisture to the granules to overcome the issue of tablet capping or lamination?
For this, we again have to take moisture application line clearance from the quality assurance department and use the same solvent to moisten the granules which was used for the kneading stage.
Practical Example
Suppose a batch of Metformin was ready for the compression process but after line clearance during parameters recording by a QA officer the tablets were capped and laminate.The operator was asked to give the sample again after reducing the tablet hardness and compression machine speed.
The issue was not resolved after reducing the tablet hardness and tablet compression machine speed.
The machine operator discussed the issue with the production manager and after discussion with the product development department & quality assurance it was decided to apply moisture or moisten the granules
Method
First of all a 5 kg or 10 trial is conducted for moisture application and we again test the sample if there is no capping and lamination we proceed to apply the moisture for the whole batch.
Take the calculated amount of solvent to be applied over granules and for this we will check the initial solvent used for kneading.
Suppose purified water was used in the formulation so we will take a calculated quantity of purified water.
Remove 10 to 15 kg of granules in a stainless steel tub and apply the moisture to it manually. After the application of moisture mix this blend and sieve it through mesh number 8 or 10.
Add the remaining quantity of batch to the double cone blender and now add the wet sieved granules in the blender as well. Close the lid of the blender and mix it for 2 to 3 minutes.
The moisture applied to 10 to 15 kg will be uniformly mixed with the remaining dry powder and in this way the over dried product will get moisture again. Now offload the batch and start the compression process.
You can also apply moisture manually by mixing the granules in a large-size polythene bag without using the double-cone blender.
For this, the total amount of solvent is divided into portions for each drum or container. Remove 4 to 5 kg granules from the drum, apply moisture, sieve it and add in large polythene bag now add the remaining dry powder from the drum or container and mix in the polthene bag.
In this way, all the drums or containers of granules are moistened.
One important thing to remember is to perform the weight adjustment calculations for individual tablet weight for the applied moisture.
Conclusion
A conventional method to overcome tablet capping and lamination is to apply moisture to the over-dried granules and for this, we apply solvent to some quantity of dried granules and then mix it with the remaining granules. An important step to keep in mind is that the moisture application method is used for those products which are manufactured by the wet granulation method.
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