Organic impurities cover a wide spectrum of compounds that have varying structures, behavior, and characteristics. They can
result from process manufacturing, storage conditions, or even degradation. Some may be volatile and may be very liable to
change as a result of exposure to heat, light, or other external factors.
A USP Expert Panel has been charged with making recommendations on revisions to General Chapter <1086> Impurities in Drugs Substances and Drug Products, General Chapter <466>—Ordinary Impurities and General Notices 5.60. Composition of the advisory Expert Panel includes representatives from pharmaceutical and over-the-counter (OTC) product
manufacturers and their trade groups (i.e., the Consumer Healthcare Products Association, Pharmaceutical Research and Manufacturers
of America, and others), members of USP's Expert Committees on Physical Analysis, Small Molecules and Toxicology, and liaisons
General Chapter <1086> includes some key definitions associated with impurities that are aligned with those established by
ICH, other pharmacopoeias and current FDA guidance. General Chapter <466> applies a relatively simple, yet old, method—thin-layer
chromatography (TLC)—for impurity detection. Although TLC enables a user to compare a test article against a known standard
and confirm the presence of that article in a sample, it is limited in its ability to distinguish between APIs, excipients,
or impurities and to accurately quantify impurities within a given sample.
The Expert Panel's review will take into account organic impurities associated with hundreds of monographs appearing in the
USP–NF, which include OTC drugs and various dosage forms associated with a single OTC. As part of its work, the Expert Panel is
assessing the feasibility of categorizing different types of organic impurities (e.g., heterocyclic compounds) and, based
on those categorizations, will explore relevant methods for detection and measurement that may be applied to multiple monographs
within a single group. For information on this effort, visit http://uspgo.to/organic-impurities.