The International Pharmacopoeia – related substances tests: dosage form monographs guidance notes
Objective:
For dosage form monographs, the main purpose of a test for related substances is to control degradation impurities. Wherever possible, however, a further objective is to limit impurities arising during synthesis of the active pharmaceutical ingredient (API). This approach provides the means for an independent control laboratory (e.g. a small regulatory laboratory) without access to manufacturer’s data to establish whether or not an API of pharmacopoeial quality has been used to manufacture the dosage form under examination. Such an approach is consistent with the aims and purpose of The International Pharmacopoeia.
General considerations:
It is recognized that the limits for degradation impurities given in dosage form monographs may sometimes need to be higher than the limits for the same impurities that appear in the monograph for the corresponding API.
The limits set for degradation impurities may also need to be different for different types of dosage form. For example, higher limits may need to be set for an oral solution than for tablets.
See below PDF for complete details:
WHO TRS (Technical Report Series) 943 Annex 1:
