#### § 558.364 Narasin and nicarbazin.

(a) *Specifications.* A fixed-ratio, combination drug Type A medicated article containing 36 grams narasin and 36 grams nicarbazin per pound.

(b) *Sponsor.* See No. 058198 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)).

(c) *Tolerances.* See [§§ 556.428](/on/2024-09-17/title-21/section-556.428) and [556.445 of this chapter](/on/2024-09-17/title-21/section-556.445).

(d) *Conditions of use.* It is used as follows:

(1) *Chickens* —

| Narasin and nicarbazin grams/ton | Combination in grams/ton | Indications for use | Limitations | Sponsor |
| --- | --- | --- | --- | --- |
| (i) 27 to 45 of each drug | | Broiler chickens: For prevention of coccidiosis caused by *Eimeria tenella, E. necatrix, E. acervulina, E. maxima, E. brunetti,* and *E. mivati* | Feed continuously as the sole ration. Do not feed to laying hens. Do not allow adult turkeys, horses, or other equines access to formulations containing narasin. Ingestion of narasin by these species has been fatal. The two drugs can be combined only at a 1:1 ratio for the 27 to 45 grams per ton range. Only granular nicarbazin as provided by No. 058198 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) may be used in the combination | 058198 |
| (ii) 27 to 45 of each drug | Bacitracin methylenedisalicylate, 4 to 50 | Broiler chickens: For the prevention of coccidiosis caused by *Eimeria necatrix, E. tenella,* *E. acervulina, E. brunetti,* *E. mivati,* and *E. maxima,* and for increased rate of weight gain and improved feed efficiency | Feed continuously as the sole ration. Do not feed to laying hens. Do not allow adult turkeys, horses, or other equines access to formulations containing narasin. Ingestion of narasin by these species has been fatal. Withdraw 5 days before slaughter. Bacitracin methylenedisalicylate as provided by No. 054771 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 058198 |
| (iii) 27 to 45 of each drug | Bacitracin methylenedisalicylate, 4 to 50 | Broiler chickens: For the prevention of coccidiosis caused by *Eimeria necatrix, E. tenella,* *E. acervulina, E. brunetti,* *E. mivati,* and *E. maxima,* and for increased rate of weight gain and improved feed efficiency | Feed as the sole ration throughout the feeding period. For broiler chickens only. Do not feed to laying hens. Do not allow adult turkeys, horses, or other equines access to formulations containing narasin. Ingestion of narasin by these species has been fatal. Bacitracin methylenedisalicylate as provided by No. 069254 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 069254 |
| (iv) 27 to 45 of each drug | Bacitracin methylenedisalicylate, 50 | Broiler chickens: For the prevention of coccidiosis caused by *Eimeria tenella, E. necatrix, E. acervulina, E. maxima, E. brunetti,* and *E. mivati,* and as an aid in the prevention of necrotic enteritis caused or complicated by *Clostridium* spp. or other organisms susceptible to bacitracin | Feed continuously as the sole ration. Do not feed to laying hens. Do not allow adult turkeys, horses, or other equines access to formulations containing narasin. Ingestion of narasin by these species has been fatal. Withdraw 5 days before slaughter. Bacitracin methylenedisalicylate as provided by No. 054771 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 054771 |
| (v) 27 to 45 of each drug | Bacitracin methylenedisalicylate, 50 | Broiler chickens: For the prevention of coccidiosis caused by *Eimeria necatrix, E. tenella, E. acervulina, E. brunetti, E. mivati,* and *E. maxima,* and for the prevention of mortality caused by necrotic enteritis associated with *Clostridium perfringens* | Feed as the sole ration for 28 to 35 days, starting from the time chicks are placed for brooding. For broiler chickens only. Do not feed to laying hens. Do not allow adult turkeys, horses, or other equines access to formulations containing narasin. Ingestion of narasin by these species has been fatal. Bacitracin methylenedisalicylate as provided by No. 069254 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 069254 |
| (vi) 27 to 45 of each drug | Bacitracin methylenedisalicylate, 100 to 200 | Broiler chickens: For prevention of coccidiosis caused by *Eimeria tenella, E. necatrix, E. acervulina, E. maxima, E. brunetti,* and *E. mivati,* and as an aid in the control of necrotic enteritis caused or complicated by *Clostridium* spp. or other organisms susceptible to bacitracin | To control necrotic enteritis, start medication at first clinical signs of disease; vary dosage based on the severity of infection; administer continuously for 5 to 7 days or as long as clinical signs persist, then reduce bacitracin to prevention level (50 g/ton). Do not feed to laying hens. Withdraw 5 days before slaughter. Do not allow turkeys, horses, or other equines access to formulations containing narasin. Ingestion of narasin by these species has been fatal. Bacitracin methylenedisalicylate as provided by No. 054771 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 054771 |
| (vii) 27 to 45 of each drug | Bambermycins, 1 to 2 | Broiler chickens: As an aid in preventing outbreaks of cecal (*Eimeria tenella*) and intestinal (*E. acervulina, E. maxima, E. necatrix,* and *E. brunetti*) coccidiosis, and for increased rate of weight gain and improved feed efficiency | Feed continuously as sole ration from time chicks are placed on litter until past the time when coccidiosis is ordinarily a hazard. Do not use as a treatment for coccidiosis. Do not feed to laying hens. Withdraw 5 days before slaughter. Do not allow turkeys, horses, or other equines access to formulations containing narasin. Ingestion of narasin by these species has been fatal. Bambermycins as provided by No. 016592 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 058198 |

(2) Narasin and nicarbazin fixed-ratio, combination drug Type A medicated articles may also be used in combination with:

(i) Avilamycin as in [§ 558.68](/on/2024-09-17/title-21/section-558.68).

(ii) Virginiamycin as in [§ 558.635](/on/2024-09-17/title-21/section-558.635).

[[83 FR 64742](https://www.federalregister.gov/citation/83-FR-64742), Dec. 18, 2018, as amended at [84 FR 8981](https://www.federalregister.gov/citation/84-FR-8981), Mar. 13, 2019; [88 FR 14907](https://www.federalregister.gov/citation/88-FR-14907), Mar. 10, 2023; [88 FR 16550](https://www.federalregister.gov/citation/88-FR-16550), Mar. 20, 2023]