What action must be taken when a substance is suddenly scheduled in relation to inventory?

When a substance is suddenly scheduled, it is required that an inventory be conducted on the date the scheduling takes effect. This action ensures that all existing stock is accounted for under the new regulatory framework. The necessity of this immediate inventory is rooted in the importance of maintaining accurate records for controlled substances, particularly when their legal status changes.

The purpose of conducting an inventory on the scheduling date is to create a formal record of all quantities on hand at a specific point in time, thereby assisting in compliance with federal and state laws. It also helps to mitigate the risk of discrepancies that could arise from not having a thorough record at the moment the substance becomes regulated.

The other options suggest no need for immediate action or alternate timing for the inventory, which does not align with the regulatory requirements set forth for the management of controlled substances under changing legal statuses. Thus, the correct requirement is to perform an inventory at the time the substance is officially scheduled.