When conducting an inventory audit, what must be subtracted from the total quantity of controlled substances?

In the context of conducting an inventory audit for controlled substances, the process involves taking stock of the existing quantities and understanding the flow of these substances. To maintain compliance with regulatory standards, it is essential to accurately reflect the changes in inventory that occur due to sales, returns, and losses.

The correct choice pertains to the quantity sold because this is a critical factor that directly decreases the total quantity of controlled substances available in the pharmacy. When substances are sold, the quantity in the inventory is reduced, necessitating a subtraction from the total amount during an audit. This reflects the actual stock on hand, ensuring that records align with physical inventory and regulatory requirements are met.

Other factors, such as quantities received or returned, affect the inventory but do not directly relate to what must be subtracted when determining the remaining controlled substances available for dispensation. Similarly, the quantity lost may have implications for record-keeping and reporting, but it does not inherently decrease stock on hand in the context of an inventory audit. Thus, subtracting the quantity sold provides a clear and accurate representation of what remains in inventory.