Drug carryover generally occurs when a drug used in the manufacture of a batch of medicated feed, for which the drug is approved, gets inadvertently included in a subsequent batch of: (1) a non-medicated feed, (2) a different medicated feed for which the drug is not approved (e.g., medicated feed for another species), or (3) a medicated feed that contains the same drug that can result in a higher drug level than is stated on the labeling.  Drug carryover can occur for various reasons, including, for example, the use of the same equipment to manufacture both medicated and non-medicated feed; the design, construction, or inadequate maintenance of feed manufacturing equipment; poor dust control in a feed mill; inadequate cleanout practices for manufacturing and distribution equipment between sequential batches of animal feed; or human error.

Our regulation “Current Good Manufacturing Practice for Medicated Feeds,” 21 CFR part 225, contains requirements for equipment cleanout procedures to avoid unsafe contamination of feeds with drugs (see 21 CFR 225.65 and 225.165).  In this guidance, we provide information on some ways to comply with these requirements to help prevent unsafe contamination of animal feed from drug carryover.  
 

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