Uncertainty In Process Control — The Limit Of Setting Limits

Setting reasonable specifications for pharmaceutical products — especially biological products — take into account:

• the manufacturing process variability
• the analytical procedure's inherent variability
• the analytical procedure's robustness and ruggedness

Although test procedures used in pharmaceutical quality control have to be validated, these validation experiments are usually performed in early development stages in special laboratories using special equipment by specially skilled analysts. This may lead to an underestimation of the procedure's variability and the setting of inappropriate — in most cases too tight — specification limits.