Today, the FDA issued a draft guidance titled Using the Inactive Ingredient Database (here). The guidance describes how to use the inactive ingredient database (IID) and its limitations.
FDA has been using the IID since 1987 and has committed to updates throughout the year that provide more current and useful information. Excipients are constantly being added or removed (if there is an associated safety issue) and their levels revised when new information is revealed or new products are approved. The biggest concern from sponsors over the years has to do with the difference between maximum strength and maximum daily exposure(the former being the quantity of excipient in one dosage unit vs the latter the maximum daily exposure [MDE] based on the dosing suggested in the drug products labeling). There has never been a good way for sponsors to determine the MDE because there is no link to the actual product in the IID. One of the FDA commitments under GDUFA II is to update the IID to include MDE and that should occur by October 1, 2020. This will be the biggest improvement to the IID since its inception.
The draft guidance provides definitions of terms, how the IID works, suggestion on how to search the database, and discusses the significance of missing values and the utility of the IID. There is also a list of useful contacts for different questions that may arise from questions the use of the IID.
We are getting closer to having a more useful aid to help determine the appropriate and safe levels of excipients in a format that is both user-friendly and more accurate.