A batch of a drug will have the same lot number and expiration date. What is true about serial numbers?

• A. Serial numbers are the same for all units
• B. Serial numbers differ between units
• C. Serial numbers are not used
• D. Serial numbers are the same as lot numbers

Answer: (B)

Serial numbers are unique identifiers assigned to individual units, separate from batch-level identifiers like lot numbers and expiration dates. In a batch, all units share the same lot number and the same expiration date, but each unit receives its own serial number so you can track each item separately. This unit-level traceability is crucial for recalls, authentication, and inventory control—if a problem is found, you can pinpoint and retrieve only the affected serial numbers rather than discarding the entire batch. So, the correct idea is that serial numbers differ between units within the same batch.