[Federal Register Volume 88, Number 214 (Tuesday, November 7, 2023)]
[Notices]
[Pages 76756-76760]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-24547]


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DEPARTMENT OF HEALTH AND HUMAN SERVICES

Food and Drug Administration

[Docket No. FDA-2023-N-4742]


Phibro Animal Health Corp.; Proposal To Withdraw Approval of New 
Animal Drug Applications for Carbadox in Medicated Swine Feed; 
Opportunity for a Hearing

AGENCY: Food and Drug Administration, HHS.

ACTION: Notice.

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SUMMARY: The Food and Drug Administration (FDA or the Agency), Center 
for Veterinary Medicine (CVM), is proposing to withdraw approval of all 
new animal drug applications (NADAs) providing for use of carbadox in 
medicated swine feed, for which Phibro Animal Health Corp., Glenpointe 
Centre East, Third Floor, 300 Frank W. Burr Blvd., Suite 21, Teaneck, 
NJ 07666-6712, is the sponsor, and is announcing an opportunity for the 
holder of the NADAs to request a hearing on this proposal. This action 
is based on CVM's determination that there is no approved regulatory 
method to detect the residue of carcinogenic concern in the edible 
tissues of the treated swine.

DATES: The sponsor of the NADAs may submit a written request for a 
hearing by December 7, 2023. Submit all data, information, and analyses 
upon which a request for a hearing relies by December 7, 2023. Either 
electronic or written comments on the notice must be submitted by 
December 7, 2023.

ADDRESSES: The request for a hearing may be submitted by the sponsor of 
the NADAs by either of the following methods:

Electronic Submissions

    Submit electronic comments in the following way:
    <bullet> Federal eRulemaking Portal: https://www.regulations.gov. 
Follow the instructions for submitting comments to submit your request 
for hearing. Your request for a hearing submitted electronically, 
including any attachments to the request for hearing, to https://www.regulations.gov will be posted to the docket unchanged.

Written/Paper Submissions

    Submit written/paper submissions as follows:
    <bullet> Mail/Hand Delivery/Courier (for written/paper request for 
a hearing): Dockets Management Staff (HFA-305), Food and Drug 
Administration, 5630 Fishers Lane, Rm. 1061, Rockville, MD 20852.

[[Page 76757]]

    <bullet> Because your request for a hearing will be made public, 
you are solely responsible for ensuring that your request does not 
include any confidential information that you or a third party may not 
wish to be publicly posted, such as confidential business information 
(e.g., a manufacturing process). The request for a hearing must include 
the Docket No. FDA-2023-N-4742 for ``Phibro Animal Health Corp.; 
Proposal to Withdraw Approval of New Animal Drug Applications for 
Carbadox in Medicated Swine Feed; Opportunity for a Hearing.'' The 
request for a hearing will be placed in the docket and publicly 
viewable at https://www.regulations.gov or at the Dockets Management 
Staff between 9 a.m. and 4 p.m., Monday through Friday, 240-402-7500.
    The sponsor of the NADAs may submit all data and analyses upon 
which the request for a hearing relies in the same manner as the 
request for a hearing except as follows:
    <bullet> Confidential Submissions--To submit any data and analyses 
with confidential information that you do not wish to be made publicly 
available, submit your data and analyses only as a written/paper 
submission. You should submit two copies total of all data and 
analyses. One copy will include the information you claim to be 
confidential with a heading or cover note that states ``THIS DOCUMENT 
CONTAINS CONFIDENTIAL INFORMATION.'' The Agency will review this copy, 
including the claimed confidential information, in its consideration of 
any decisions on this matter. The second copy, which will have the 
claimed confidential information redacted/blacked out, will be 
available for public viewing and posted on https://www.regulations.gov 
or available at the Dockets Management Staff between 9 a.m. and 4 p.m., 
Monday through Friday. Submit both copies to the Dockets Management 
Staff. Any information marked as ``confidential'' will not be disclosed 
except in accordance with 21 CFR 10.20 and other applicable disclosure 
law.
    Comments Submitted by Other Interested Parties: For all comments 
submitted by other interested parties, submit comments as follows. 
Please note that late, untimely filed comments will not be considered. 
The https://www.regulations.gov electronic filing system will accept 
comments until 11:59 p.m. Eastern Time at the end of December 7, 2023. 
Comments received by mail/hand delivery/courier (for written/paper 
submissions) will be considered timely if they are received on or 
before that date.

Electronic Submissions

    Submit electronic comments in the following way:
    <bullet> Federal eRulemaking Portal: https://www.regulations.gov. 
Follow the instructions for submitting comments. Comments submitted 
electronically, including attachments, to https://www.regulations.gov 
will be posted to the docket unchanged. Because your comment will be 
made public, you are solely responsible for ensuring that your comment 
does not include any confidential information that you or a third party 
may not wish to be posted, such as medical information, your or anyone 
else's Social Security number, or confidential business information, 
such as a manufacturing process. Please note that if you include your 
name, contact information, or other information that identifies you in 
the body of your comments, that information will be posted on https://www.regulations.gov.
    <bullet> If you want to submit a comment with confidential 
information that you do not wish to be made available to the public, 
submit the comment as a written/paper submission and in the manner 
detailed (see ``Written/Paper Submissions'' and ``Instructions'').

Written/Paper Submissions

    Submit written/paper submissions as follows:
    <bullet> Mail/Hand Delivery/Courier (for written/paper 
submissions): Dockets Management Staff (HFA-305), Food and Drug 
Administration, 5630 Fishers Lane, Rm. 1061, Rockville, MD 20852.
    <bullet> For written/paper comments submitted to the Dockets 
Management Staff, FDA will post your comment, as well as any 
attachments, except for information submitted, marked and identified, 
as confidential, if submitted as detailed in ``Instructions.''
    Instructions: All submissions received must include the Docket No. 
FDA-2023-N-4742 for ``Phibro Animal Health Corp.; Proposal to Withdraw 
Approval of New Animal Drug Applications for Carbadox in Medicated 
Swine Feed; Opportunity for a Hearing.'' Received comments, those filed 
in a timely manner (see ADDRESSES), will be placed in the docket and, 
except for those submitted as ``Confidential Submissions,'' publicly 
viewable at https://www.regulations.gov or at the Dockets Management 
Staff between 9 a.m. and 4 p.m., Monday through Friday, 240-402-7500.
    <bullet> Confidential Submissions--To submit a comment with 
confidential information that you do not wish to be made publicly 
available, submit your comments only as a written/paper submission. You 
should submit two copies total. One copy will include the information 
you claim to be confidential with a heading or cover note that states 
``THIS DOCUMENT CONTAINS CONFIDENTIAL INFORMATION.'' The Agency will 
review this copy, including the claimed confidential information, in 
its consideration of comments. The second copy, which will have the 
claimed confidential information redacted/blacked out, will be 
available for public viewing and posted on https://www.regulations.gov. 
Submit both copies to the Dockets Management Staff. If you do not wish 
your name and contact information to be made publicly available, you 
can provide this information on the cover sheet and not in the body of 
your comments and you must identify this information as 
``confidential.'' Any information marked as ``confidential'' will not 
be disclosed except in accordance with 21 CFR 10.20 and other 
applicable disclosure law. For more information about FDA's posting of 
comments to public dockets, see 80 FR 56469, September 18, 2015, or 
access the information at: https://www.govinfo.gov/content/pkg/FR-2015-09-18/pdf/2015-23389.pdf.
    Docket: For access to the docket to read background documents or 
the electronic and written/paper comments received, go to https://www.regulations.gov and insert the docket number, found in brackets in 
the heading of this document, into the ``Search'' box and follow the 
prompts and/or go to the Dockets Management Staff, 5630 Fishers Lane, 
Rm. 1061, Rockville, MD 20852, 240-402-7500.

FOR FURTHER INFORMATION CONTACT: Diane Heinz, Center for Veterinary 
Medicine (HFV-6), Food and Drug Administration, 7500 Standish Pl., 
Rockville, MD 20855, 240-402-5692.

SUPPLEMENTARY INFORMATION: 

I. Approved NADAs for Use of Carbadox in Swine Feed

    Carbadox, a quinoxaline derivative, is a synthetic organic acid 
antimicrobial. Currently, there are three approved NADAs for use of 
carbadox in medicated swine feed, either by itself or in combination 
with other approved new animal drugs. Phibro Animal Health Corp., 
Glenpointe Centre East, Third Floor, 300 Frank W. Burr Blvd., Suite 21, 
Teaneck, NJ 07666-6712, is currently the sponsor of all three approved 
NADAs.
    Carbadox is marketed as a Type A medicated article used to 
manufacture complete Type C medicated feeds that are administered ad 
libitum (available at all times) to swine. Carbadox is

[[Page 76758]]

indicated for the control of dysentery and bacterial enteritis, and for 
growth promotion. A tolerance of 30 parts per billion (ppb) has been 
established for residues of quinoxaline-2-carboxylic acid (QCA), the 
marker residue, in liver of swine (21 CFR 556.100). The combination 
products containing carbadox (carbadox and pyrantel, and carbadox and 
oxytetracycline) are also approved for additional indications related 
to the non-carbadox active ingredient.
    The following three NADAs are approved for the use of carbadox:
    NADA 041-061, originally approved in 1972 (37 FR 20683, October 3, 
1972), provides for the use of MECADOX 10 (carbadox) Type A medicated 
article to manufacture single-ingredient Type C medicated swine feeds 
for the following conditions of use:
    Carbadox at 10 to 25 grams per ton (g/ton) of feed for increased 
rate of weight gain and improved feed efficiency; and
    Carbadox at 50 g/ton of feed for control of swine dysentery 
(vibrionic dysentery, bloody scours, or hemorrhagic dysentery); for 
control of bacterial swine enteritis (salmonellosis or necrotic 
enteritis caused by Salmonella choleraesuis); and for increased rate of 
weight gain and improved feed efficiency.
    In January 1998, CVM approved a supplemental application to NADA 
041-061, which included the approved method.
    In October 1998, CVM approved an additional supplemental NADA for 
NADA 041-061, changing the withdrawal period for carbadox medicated 
feeds from 70 days to 42 days.
    Currently, the withdrawal period for these uses of carbadox is 42 
days (Sec.  558.115(d)(1)(ii) and (d)(2)(ii) (21 CFR 558.115(d)(1)(ii) 
and (d)(2)(ii))).
    NADA 092-955, originally approved in 1975 (40 FR 45164, October 1, 
1975), provides for the use of MECADOX 10 (carbadox) Type A medicated 
article with BANMINTH (pyrantel tartrate) Type A medicated article to 
manufacture two-way, combination drug Type C medicated swine feeds for 
the following conditions of use:
    Carbadox at 50 g/ton of feed plus pyrantel tartrate at 96 g/ton of 
feed for control of swine dysentery (vibrionic dysentery, bloody 
scours, or hemorrhagic dysentery); for control of bacterial swine 
enteritis (salmonellosis or necrotic enteritis caused by Salmonella 
choleraesuis); as an aid in the prevention of migration and 
establishment of large roundworm (Ascaris suum) infections; and as an 
aid in the prevention of establishment of nodular worm 
(Oesophagostomum) infections.
    The withdrawal period for the use of this drug combination is 70 
days (Sec.  558.115(d)(3)(ii)).
    NADA 141-211, originally approved in 2004 (69 FR 51173, August 18, 
2004), provides for the use of MECADOX 10 (carbadox) Type A medicated 
article with TERRAMYCIN 50, TERRAMYCIN 100, or TERRAMYCIN 200 
(oxytetracycline) Type A medicated articles to manufacture two-way, 
combination drug Type C medicated swine feeds for the following 
conditions of use:
    Carbadox at 10 to 25 g/ton of feed plus oxytetracycline at levels 
in feed to deliver 10 mg oxytetracycline per pound of body weight for 
treatment of bacterial enteritis caused by Escherichia coli and S. 
choleraesuis susceptible to oxytetracycline; for treatment of bacterial 
pneumonia caused by Pasteurella multocida susceptible to 
oxytetracycline; and for increased rate of weight gain and improved 
feed efficiency.
    The withdrawal period for the use of this animal drug combination 
is 42 days (Sec.  558.115(d)(4); Sec.  558.450(e)(3)(iii)).

II. Basis for Withdrawal of Approval

    FDA is providing notice of an opportunity for a hearing (NOOH) on 
CVM's proposal to withdraw approval of the NADAs providing for use of 
carbadox in medicated swine feeds. New evidence demonstrates that the 
Delaney Clause in section 512(d)(1)(I) of the Federal Food, Drug, and 
Cosmetic Act (FD&C Act) (21 U.S.C. 360b(d)(1)(I)), which requires that 
no residue of a carcinogenic drug can be found in any edible portion of 
the animal after slaughter, applies because the Diethylstilbestrol 
(DES) Proviso exception is no longer met (see section III).
    Section 512(e)(1)(B) of the FD&C Act provides grounds for 
withdrawal of approval of an NADA if new evidence not contained in such 
application or not available until after such application was approved, 
tests by new methods, or tests by methods not deemed reasonably 
applicable when such application was approved, evaluated together with 
the evidence available when the application was approved, shows that 
the Delaney Clause, section 512(d)(1)(I) of the FD&C Act, applies to 
the drug. Under the Delaney Clause, the Secretary shall not approve a 
new animal drug application if ``such drug induces cancer when ingested 
by man or animal or, after tests which are appropriate for the 
evaluation of the safety of such drug, induces cancer in man or 
animal'' (section 512 (d)(1)(I) of the FD&C Act). An exception to this 
general rule, referred to as the ``DES Proviso,'' allows for the 
approval of a carcinogenic new animal drug where FDA finds that, under 
the approved conditions of use: (1) The drug will not adversely affect 
the animals treated with the drug, and (2) no residues of the drug will 
be found by an approved regulatory method in any edible tissues of or 
in any foods yielded by the animal (section 512(d)(1)(I)(i) through 
(ii) of the FD&C Act).
    Evidence available at the time of the approvals showed that 
carbadox was carcinogenic. At the time of the January 1998 supplemental 
approval, CVM concluded that carcinogenic residues, including 
desoxycarbadox (DCBX), a known carcinogenic metabolite of carbadox, 
depleted quickly (within 72 hours) while QCA residues depleted more 
slowly (Ref. 1). However, new evidence not available at the time of the 
approval, including studies conducted by the sponsor and submitted to 
FDA from 2005 to 2016 and a study conducted by a third party and 
summarized in a publication in 2022,\1\ demonstrates that the residue 
of carcinogenic concern persists longer than previously known (Refs. 2 
to 4). Because there is no established relationship between 
concentrations of QCA measured by the approved method and 
concentrations of the residue of carcinogenic concern, the approved 
regulatory method cannot be used to measure the residue of carcinogenic 
concern.
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    \1\ ``Metabolism and Tissue Depletion of Carbadox in Swine, 
Broilers, and Rats,'' Jie Zhang, Wei Qu, Zongchao Wang, and Yuanhu 
Pan, ACS Agricultural Science & Technology 2022 2 (3), 477-485.
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    Elsewhere in today's Federal Register, FDA is publishing a final 
order (Ref. 5) revoking the approved regulatory method for carbadox 
that measures QCA as a marker residue to detect the presence of any 
residue of carcinogenic concern (Ref. 6). Currently, therefore, there 
is no approved regulatory method for carbadox, and the second prong of 
the DES Proviso is not met.

III. Background Information Regarding the Regulation of Carcinogenic 
New Animal Drugs

    Under the Delaney Clause of the FD&C Act, the Secretary shall not 
approve a carcinogenic new animal drug application unless the DES 
Proviso applies (section 512(d)(1)(I)(i) through (ii) of the FD&C Act). 
FDA has issued implementing regulations that set the requirements for 
demonstrating that no residues of the drug will be found by an approved 
regulatory method in any

[[Page 76759]]

edible tissues of or in any foods yielded from the animal (21 CFR part 
500, subpart E). These regulations, referred to as the sensitivity of 
the method regulations (SOM regulations), describe how FDA determines 
whether the regulatory method proposed by a sponsor is sufficiently 
sensitive to ensure that residues of carcinogenic concern in edible 
tissues will not exceed concentrations that represent no significant 
increase in the risk of cancer to humans.
    Pursuant to these regulations, FDA determines for each drug and 
each drug metabolite (on the basis of the results of chronic bioassays 
and other information) whether the drug or any of its metabolites are 
carcinogenic (Sec.  500.84(a) (21 CFR 500.84(a))). For the drug and 
each metabolite determined to be carcinogenic, FDA calculates, based 
upon submitted assays, the concentration of the test compound in the 
total diet of the test animal that corresponds to a maximum lifetime 
risk of cancer in the test animal of 1 in 1 million (Sec. Sec.  
500.82(b) (21 CFR 500.82(b)) and 500.84(c)(1)). FDA designates the 
lowest value thus calculated as the S<INF>o</INF> (Sec. Sec.  500.82(b) 
and 500.84(c)(1)). The S<INF>o</INF> corresponds to a concentration of 
residue of carcinogenic concern in the total human diet that represents 
no significant increase in the risk of cancer to people (Sec.  
500.82(b)). Residue of carcinogenic concern includes all compounds in 
the total residue of a demonstrated carcinogen excluding any compound 
judged by FDA not to present a carcinogenic risk (Sec.  500.82(b)). The 
total residues of carcinogenic concern (the drug and all of its 
metabolites less metabolites shown to be noncarcinogenic) are regulated 
based on the most potent carcinogenic residue (Sec.  500.84(c)(1)). 
This approach ensures that use of the drug does not present a 
significant increase in the risk of cancer when considering all 
residues in edible tissues.
    Because the total diet is not derived only from food-producing 
animals, the SOM regulations make adjustments for human food intake of 
edible tissues and determine the concentration of residues of 
carcinogenic concern in a specific edible tissue that corresponds to no 
significant increase in the risk of cancer to the human consumer. FDA 
assumes for purposes of these regulations that this value will 
correspond to the concentration of residues in a specific edible tissue 
that corresponds to a maximum lifetime risk of cancer in test animals 
of 1 in 1 million. This value is termed the S<INF>m</INF> (Sec. Sec.  
500.82(b) and 500.84(c)(1)).
    Based on residue depletion data submitted by a sponsor, FDA selects 
a target tissue (the edible tissue selected to monitor for residues in 
the target animals) and a marker residue (a residue whose concentration 
is in a known relationship to the concentration of the residues of 
carcinogenic concern in the last tissue to deplete to the 
S<INF>m</INF>) and designates the concentration of the marker residue 
that the regulatory method must be capable of detecting in the target 
tissue (Sec.  500.86(a) through (c) (21 CFR 500.86(a) through (c))). 
This value, termed the R<INF>m</INF>, is the concentration of a marker 
residue in the target tissue when the residue of carcinogenic concern 
is equal to S<INF>m</INF> (Sec.  500.82(b)). When the marker residue is 
at or below the R<INF>m</INF>, the residue of carcinogenic concern in 
the human diet does not exceed S<INF>o</INF> (Sec.  500.86(c)). This 
regulation ensures that when the marker residue is no longer 
detectable, the residue of carcinogenic concern does not exceed 
S<INF>m</INF> in any of the edible tissues (Sec. Sec.  500.82(b) and 
500.86(c)).
    A sponsor must submit a regulatory method that is able to detect 
the marker residue at or below the R<INF>m</INF> (21 CFR 500.88(b) and 
500.84(c)(2)) (``The LOD [Limit of Detection for the regulatory method] 
must be less than or equal to R<INF>m</INF>.'')). If a method is not 
developed that can detect the marker residue at or below the 
R<INF>m</INF>, the requirements of the SOM regulations are not 
satisfied, and FDA cannot approve the drug. The DES Proviso and FDA's 
implementing regulations are satisfied where no marker residue is 
detectable using the approved regulatory method under the proposed 
conditions of use of the drug, including the proposed preslaughter 
withdrawal period (Sec.  500.84(c)(3)).

IV. Notice of Opportunity for a Hearing

    CVM is proposing to withdraw approval of the three NADAs that 
provide for use of carbadox in swine feed because new evidence 
demonstrates that the drug does not meet the DES Proviso exception to 
the Delaney Clause. There is currently no approved regulatory method 
for carbadox.
    Therefore, notice is given to Phibro Animal Health Corp., 
Glenpointe Centre East, Third Floor, 300 Frank W. Burr Blvd., Suite 21, 
Teaneck, NJ 07666-6712, and to all other interested persons, that the 
Deputy Commissioner for Policy, Legislation, and International Affairs, 
Office of Policy, Legislation, and International Affairs proposes to 
issue an order under section 512(e) of the FD&C Act withdrawing 
approval of all NADAs providing for use of carbadox in medicated swine 
feed.
    In accordance with section 512 of the FD&C Act and 21 CFR part 514 
and under the authority delegated to the Deputy Commissioner for 
Policy, Legislation, and International Affairs, Office of Policy, 
Legislation, and International Affairs by the Commissioner of Food and 
Drugs, Phibro Animal Health Corp., the sponsor, is hereby given an 
opportunity for a hearing to show why approvals of NADA 041-061, 092-
955, and 141-211 should not be withdrawn.
    If the sponsor, Phibro Animal Health Corp., wishes to request a 
hearing, the sponsor must file the following: (1) a written notice of 
participation and request for a hearing (see DATES and ADDRESSES) and 
(2) the data, information, and analyses relied on to demonstrate that 
there is a genuine and substantial issue of fact that requires a 
hearing (see DATES and ADDRESSES). Any other interested person may also 
submit comments on this notice. Procedures and requirements governing 
this NOOH, a notice of appearance and request for a hearing, submission 
of data, information, and analyses to justify a hearing, other 
comments, and a grant or denial of a hearing, are contained in Sec.  
514.200 (21 CFR 514.200) and 21 CFR part 12.
    The failure of a holder of an approval to timely file a request for 
a hearing as required by Sec.  514.200 constitutes an election by the 
holder not to avail itself of the opportunity for a hearing and 
constitutes a waiver of any contentions concerning the legal status of 
any such drug product, and the Director of CVM will summarily enter a 
final order withdrawing the approvals. Any new animal drug product 
marketed without an approved NADA is subject to regulatory action at 
any time.
    A request for a hearing may not rest upon mere allegations or 
denials but must set forth specific facts showing that there is a 
genuine and substantial issue of fact that requires a hearing. If it 
conclusively appears from the face of the data, information, and 
factual analyses in the request for hearing that there is no genuine 
and substantial issue of fact that precludes the withdrawal of approval 
of the applications, or when a request for hearing is not made in the 
required format or with the required analyses, the Commissioner of Food 
and Drugs will enter summary judgment against the person who requests a 
hearing, making findings and conclusions, and denying a hearing.
    If a hearing is requested and is justified by the sponsor's 
response to this NOOH, the issues will be defined,

[[Page 76760]]

a presiding officer will be assigned, and a written notice of the time 
and place at which the hearing will commence will be issued as soon as 
practicable.
    This notice is issued under section 512 of the FD&C Act and under 
the authority delegated to the Deputy Commissioner for Policy, 
Legislation, and International Affairs, Office of Policy, Legislation, 
and International Affairs.

V. Environmental Impact

    The Agency has determined under 21 CFR 25.33(g) that this action is 
of a type that does not individually or cumulatively have a significant 
impact on the human environment. Therefore, neither an environmental 
assessment nor an environmental impact statement is required.

VI. References

    The following references are on display in the Dockets Management 
Staff (see ADDRESSES) and are available for viewing by interested 
persons between 9 a.m. and 4 p.m., Monday through Friday; they are also 
available electronically at https://www.regulations.gov. Although FDA 
verified the website addresses in this document, please note that 
websites are subject to change over time.

1. FDA, Freedom of Information Summary, NADA 041-061, MECADOX 10 
(carbadox) Type A medicated article, supplemental approval January 
30, 1998. Available at https://animaldrugsatfda.fda.gov/adafda/app/search/public/document/downloadFoi/308.
2. Evaluations of the Joint Food and Agriculture Organization of the 
United Nations/World Health Organization Expert Committee on Food 
Additives (JECFA). Carbadox. 2021. Available at: https://apps.who.int/food-additives-contaminants-jecfa-database/Home/Chemical/2176.
3. Memorandum to File entitled ``CVM Response to Phibro Animal 
Health Corporation's September 18, 2020 Comments on CVM's July 20, 
2020 Proposed Order to Revoke the Regulatory Method for Carbadox'' 
(January 6, 2022).
4. Memorandum to File entitled ``CVM review of comments on the Zhang 
article that Phibro references in the document submitted to the Part 
15 Hearing docket under cover letter dated June 9, 2022, and 
entitled, `Phibro Animal Health Corporation's Reply to the January 
6, 2022 `CVM Response to Phibro Animal Health Corporation's 
September 18, 2020 Comments on CVM's July 20, 2020 Proposed Order to 
Revoke the Regulatory Method for Carbadox.' ' '' (October 30, 2023).
5. Phibro Animal Health Corp.; Carbadox in Medicated Swine Feed; 
Revocation of Approved Method (November 7, 2023).
6. ``Determination of Carbadox as Quinoxaline-2-carboxylic Residues 
in Swine Liver and Muscle Tissues after Drug Withdrawal.'' Available 
at https://www.fda.gov/media/136267/download.

    Dated: November 1, 2023.
Kimberlee Trzeciak,
Deputy Commissioner for Policy, Legislation, and International Affairs.
[FR Doc. 2023-24547 Filed 11-6-23; 8:45 am]
BILLING CODE 4164-01-P