The process validation of pilot lots or scale-ups actually refers to testing two aspects of the manufacturing process: the manufacturing time intervals as well as manufacturing volumes.
In manufacturing time intervals, process validation ensures that the product remains consistent within an acceptable range in each step of the manufacturing process by testing samples taken from the beginning, middle and end of the products’ development. For example, if manufacturing 2% salicylic acid, the samples taken from the beginning, middle and end of the process should have within 1.8 – 2.2% specific range.
In the situation where the developing product is held in holding or mixing tanks, process validation engages in testing manufacturing volumes. The validation process uses samples from the top, center, and bottom of the tank to ensure homogeneity in the entire mixture. In the blending of solid, liquid or semi-solid raw materials, manufacturers must make certain that the entire batch is thoroughly mixed.