I recently went through an internal audit in which we reviewed the DHF of one of our product lines. There was heavy debate on information within the Design Specification Document (DID). The DID contains specific specifications and tolerances for drawings of the actual product that is to be manufactured. Each product must be made to the drawing and each measurement must fit within the specs and tolerances and pass QC inspection. Our DID had extremely tight tolerances for one of the measurements in the drawing and the yields for that product were very low since we were failing them at QC inspection due to out of spec measurements. If those out of spec products passed through QC, this error could have potentially led to FDA warning letters.

In retrospect it would have been better to open the tolerances before this drawing was created. We had to go back and open Change Controls to adjust the specs. In addition we had to update the DDP and update the DID again.

To ensure your DHF is audit ready these documents should be reviewed on a consistent basis well before an actual audit occurs. In addition, the DHF should be reviewed by all departments involved which includes Marketing, Engineering, Research and Development, and Regulatory. Each of these departments should provide some level of input on any specific findings or changes that are occurring within the DHF and should be communicating the updates the rest of the team.