Section 530.41 - Drugs prohibited for extralabel use in animals(a) The following drugs, families of drugs, and substances are prohibited for extralabel animal and human drug uses in food-producing animals.(3) Diethylstilbestrol (DES);(6) Other nitroimidazoles;(9) Sulfonamide drugs in lactating dairy cattle (except approved use of sulfadimethoxine, sulfabromomethazine, and sulfaethoxypyridazine);(10) Fluoroquinolones; and(12) Phenylbutazone in female dairy cattle 20 months of age or older.(13) Cephalosporins (not including cephapirin) in cattle, swine, chickens, or turkeys:(i) For disease prevention purposes;(ii) At unapproved doses, frequencies, durations, or routes of administration; or(iii) If the drug is not approved for that species and production class.(b) The following drugs, families of drugs, and substances are prohibited for extralabel animal and human drug uses in nonfood-producing animals: [Reserved](d) The following drugs, or classes of drugs, that are approved for treating or preventing influenza A, are prohibited from extralabel use in chickens, turkeys, and ducks:(2) Neuraminidase inhibitors.62 FR 27947, May 22, 1997, as amended at 67 FR 5471 , Feb. 6, 2002; 68 FR 9530 , Feb. 28, 2003; 68 FR 14134 , Mar. 24, 2003; 71 FR 14377 , Mar. 22, 2006; 77 FR 745 , Jan. 6, 2012