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US Pharmacopeia
According to the warning letters:
• Pharmaceutical manufacturers must perform at least one
test to verify the identity of each drug component; and
• If relying on COAs from suppliers for conformity with
other appropriate written specifications, manufacturers
must validate and establish the reliability of the suppli-
ers' test analyses at appropriate intervals.
Analysis of excipient-related FDA warning letters
USP staff reviewed the FDA warning letters posted on fda.gov
for cGMP violations issued by CDER's Office of Manufactur-
ing Quality and the Office of Regulatory Affairs (ORA) district
offices from 2013 through 2018 to pharmaceutical manufac-
turers that marketed drugs in the US. USP staff searched the
letters for keywords that indicated excipient testing issues,
such as excipient (or a specific excipient), inactive ingredi-
ent, drug components, or raw materials, separate from active
pharmaceutical ingredients and noted the specific Code of
Federal Regulations (CFR) violations cited in the warning let-
ters. Table 1 shows the number of FDA warning letters issued
to drug product manufacturers each year that mention excip-
ients or inactive ingredients for the years analyzed.
Table 1
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