Hi Elena,
FDA Study Data Technical Conformance Guide: "We recommend that sponsors obtain UNII codes for unapproved substances as early in drug development as possible, so that relevant information, such as study data, can be unambiguously linked to those substances."
Data standards are not design to handle data quality issues. There is no guidance for such cases.
I would follow FDA requirement and common sense
-
Apply for new UNII code if needed, obtain and use it
-
Until its availability,
- use a custom term for TSVAL
- not populate any of TSVALCD, TSVCDREF and TSVCDVER variables as not applicable
- explain the issue in Reviewers’ Guide
- ensure that your company have applied for a new UNII entity in case if later FDA will ask you to provide a registered term
Regards,
Sergiy