Which of the following is NOT a requirement for initial inventory?

The requirement for an initial inventory in the context of controlled substances is governed by regulations that prioritize specific details about the substances on hand. An initial inventory must include the date the inventory was taken, the name of the controlled substances, and the number of dosage units present to ensure accurate record-keeping and adherence to regulatory standards.

While exact weight can be important for certain substances, particularly for solid dosage forms such as tablets or capsules, it is not a universal requirement for all controlled substances. In many cases, inventory records can be sufficiently maintained with the total number of dosage units instead of needing the precise weight. Thus, the requirement for inventory does not universally mandate the exact weight of substances, which is why the choice pertaining to "exact weight of substances" is highlighted as an incorrect requirement for initial inventory.