# Zilpaterol.
**AGENCY:**
Food and Drug Administration, HHS.
**ACTION:**
Final rule; technical amendment.
**SUMMARY:**
The Food and Drug Administration (FDA) is amending the animal drug regulations to reflect approval of a new animal drug application (NADA) filed by Intervet Inc. The NADA provides for use of approved, single-ingredient Type A medicated articles containing zilpaterol hydrochloride, monensin USP, tylosin phosphate, and melengestrol acetate in four-way combination Type B and Type C medicated feeds for heifers fed in confinement for slaughter.
**DATES:**
This rule is effective April 8, 2008.
**FOR FURTHER INFORMATION CONTACT:**
Gerald L. Rushin, Center for Veterinary Medicine (HFV-126), Food and Drug Administration, 7500 Standish Pl., Rockville, MD 20855, 240-276-8103, e-mail: *[email protected]* .
**SUPPLEMENTARY INFORMATION:**
Intervet Inc., P.O. Box 318, 29160 Intervet Lane, Millsboro, DE 19966, filed NADA 141-280 that provides for use of ZILMAX (zilpaterol hydrochloride), and RUMENSIN (monensin USP), TYLAN (tylosin phosphate), and MGA (melengestrol acetate) Type A medicated articles to make dry and liquid four-way combination Type B and Type C medicated feeds used for increased rate of weight gain, improved feed efficiency, and increased carcass leanness; for prevention and control of coccidiosis due to *Eimeria bovis* and *E. zuernii* ; and for reduction of incidence of liver abscesses caused by *Fusobacterium necrophorum* and *Arcanobacterium* ( *Actinomyces* ) *pyogenes* ; and suppression of estrus (heat) in heifers fed in confinement for slaughter during the last 20 to 40 days on feed. The NADA is approved as of February 29, 2008, and the regulations in 21 CFR 558.342 and 558.665 are amended to reflect the approval.
In addition, FDA has noticed that the codified indications for use of tylosin in combination with melengestrol and lasalocid are not consistent with the conditions of use approved for an abbreviated new animal drug application (71 FR 39204, July 12, 2006). At this time, the indications for use are revised to include the associated pathogens. This action is being taken to improve the accuracy of the regulations.
In accordance with the freedom of information provisions of 21 CFR part 20 and 21 CFR 514.11(e)(2)(ii), a summary of safety and effectiveness data and information submitted to support approval of this application may be seen in the Division of Dockets Management (HFA-305), Food and Drug Administration, 5630 Fishers Lane, rm. 1061, Rockville, MD 20852, between 9 a.m. and 4 p.m., Monday through Friday.
The agency has determined under 21 CFR 25.33(a)(2) that this action is of a type that does not individually or cumulatively have a significant effect on the human environment. Therefore, neither an environmental assessment nor an environmental impact statement is required.
This rule does not meet the definition of “rule” in 5 U.S.C. 804(3)(A) because it is a rule of “particular applicability.” Therefore, it is not subject to the congressional review requirements in 5 U.S.C. 801-808.
**List of Subjects in 21 CFR Part 558**
Animal drugs, Animal feeds.
**21 CFR Part 558**
Therefore, under the Federal Food, Drug, and Cosmetic Act and under authority delegated to the Commissioner of Food and Drugs and redelegated to the Center for Veterinary Medicine, 21 CFR part 558 is amended as follows:
**21 CFR Part 558**
**PART 558—NEW ANIMAL DRUGS FOR USE IN ANIMAL FEEDS**
1. The authority citation for 21 CFR part 558 continues to read as follows:
**Authority:**
21 U.S.C. 360b, 371.
**21 CFR Part 558**
2. In § 558.342, revise paragraphs (e)(1)(iv) and (e)(2) to read as follows:
§ 558.342
(e) * * *
(1) * * *
| Melengestrol | Combination in | Indications for use | Limitations | Sponsor |
| --- | --- | --- | --- | --- |
| * * * * * * * | | | | |
| (iv) 0.25 to 0.5 | Lasalocid 100 to 360 plus tylosin 90. | Heifers fed in confinement for slaughter: As in paragraph (e)(1)(i) of this section; and for reduced incidence of liver abscesses caused by
and
. | To administer 0.25 to 0.5 mg melengestrol acetate plus 100 to 360 mg lasalocid plus 90 mg tylosin/head/day: | 000009, |
| * * * * * * * | | | | |
(2) Melengestrol may also be used with:
(i) Ractopamine as in § 558.500 of this chapter.
(ii) Zilpaterol as in § 558.665 of this chapter.
**21 CFR Part 558**
3. In § 558.665, add paragraph (e)(5) to read as follows:
§ 558.665
(e) * * *
| Zilpaterol in | Combination in | Indications for use | Limitations | Sponsor |
| --- | --- | --- | --- | --- |
| * * * * * * * | | | | |
| (5) 6.8 to provide 60 to 90 mg/head/day. | Monensin 10 to 40, plus tylosin 8 to 10, plus melengestrol acetate to provide 0.25 to 0.5 mg/ head/day. | Heifers fed in confinement for slaughter: As in paragraph (e)(1) of this section; for prevention and control of coccidiosis due to
and
; for reduction of incidence of liver abscesses caused by
and
; and for suppression of estrus (heat). | As in paragraph (e)(1) of this section; see §§ 558.342(d), 558.355(d), and 558.625(c) of this chapter. Monensin and tylosin as provided by No. 000986; melengestrol acetate as provided by No. 000009 in § 510.600(c) of this chapter. | 057926 |
Dated: March 24, 2008.
Bernadette Dunham,
Director, Center for Veterinary Medicine.