Customer N came to us with a product which had been formulated at their site, seemingly passing their manufacturing specification. However, it was found that on storage the product was not stable – the active ingredient had agglomerated, causing it to fall out of suspension forming a “cake” layer of solid material at the base of the bottle. The subsequent physical properties of this formulated product meant that customer N could not release the product for sale.
Issues with reworking products
The standard method of reworking highly “caked” product is to cut open the bottle, remove the supernatant and scrape out the active ingredient into a holding vessel. This solid / liquid combination then requires high shear mixing until homogeneous. The homogenous liquid is subsequently pumped into a mixing vessel for final stabilization of the product. The normal stabilization of the product is based on routine manufactured product.
This current method of re-working highly “caked” product is therefore very inefficient, with high yield losses and risk assessment implications.
Overcoming practical concerns: new process development
It was realized that re-homogenizing the separated product in its primary pack before decanting would mean no yield losses of the product, allowing the stabilization process to have shorter process time and less product temperature issues.
The process developed to carry out this theory was a machine that could rotate a pallet of bottles in both clockwise and anticlockwise directions at different RPM. The mechanics of this caused different fluid flow dynamics inside the bottles, allowing for more efficient homogenization. The protocol required different rotational patterns and grading of the product to decide the optimum parameters for the different “caked” batches of manufactured product.
The stabilization of the product after homogenization required determining the ratio of thickener and clay to keep the product in suspension for the shelf life of the product. The ratio of the two had to be so that the product was still pourable, but with enough structure that the active did not fall out of suspension causing “caking” again.
The result was that the product was able to be salvaged and made reusable with no product yield losses, saving the customer a considerable amount of money!