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U.S. Department of Health and Human Services

Animal & Veterinary

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NADA 092-287 CLCT 50 MR & 100 MR - supplemental approval (February 16, 1996)


Sponsor:Pfizer Inc
West Chester, PA
Generic Name:chlortetracycline pre-mix milk replacer
Trade Name:CLCT 50 MR & 100 MR
Marketing Status:Over the Counter (OTC)
Effect of Supplement:The effect of this Category II supplement is to bring the drug product into compliance with the National Academy of Science/National Research Council/ Drug Efficacy Study Implementation (NAS/NRC/DESI) recommendations.


See below


A.DOSAGE FORMType A Medicated Feed


DosageIndication for use
0.1 mg/pound body weight dailyCalves (up to 250 lbs.): For an increased rate of weight gain and improved feed efficiency.
25-70 mg/head/dayCalves (250-400 lbs.): For an increased rate of weight gain and improved feed efficiency.

WARNING: Zero-day withdrawal period

DosageIndication for use
10 mg/pound body weight dailyTreatment of bacterial enteritis caused by Escherichia coli.

WARNING: Withdraw 10 days prior to slaughter.



The drug was the subject of National Academy of Science/National Research Council (NAS/NRC) reports which were published in the FEDERAL REGISTER of July 21, 1970 (35 FR 11647). The Academy evaluated these products as probably effective for growth promotion and feed efficiency and the treatment of animal diseases caused by pathogens sensitive to chlortetracycline.

The Academy states that: (1) Claims made regarding "for prevention of" or "to prevent" should be replaced with "as an aid in the control of" or "to aid in the control of"; (2) claims for growth promotion or stimulation are disallowed and claims for faster gains and/or feed efficiency should be stated as "may result in faster gains and/or improved feed efficiency under appropriate conditions"; (3) each disease claim should be properly qualified as "appropriate for use in (name of disease) caused by pathogens sensitive to (name of drug) "; if the disease cannot be so qualified the claim must be dropped; (4) claims pertaining to egg production and hatchability should be changed to "May aid in maintaining egg production and hatchability, under appropriate conditions, by controlling pathogenic microorganisms"; (5) the labels should warn that treated animals must actually consume enough medicated water or medicated feed to provide a therapeutic dosage under the conditions that prevail and, as a precaution, state the desired oral dose per unit of animal weight per day for each species as a guide to effective usage of the preparation in drinking water or feed: and (6) effective blood levels are required for each recommended dosage.

The Food and Drug Administration concurs with the Academy's findings, interpreting the phrase "...cannot be so qualified..." in paragraph (3) to mean "...is not supported by adequate data..." (See Fed. Reg. vol. 35, NO. 140-Tues., July 21, 1970). FDA proceeded to review all available data relating to the effectiveness of products subject to NADA 92-287 to determine which label claims were supported by the requisite proof of effectiveness. That review resulted in a letter to the sponsor in which the agency stated that it had concluded that such data supported effectiveness only for the control and treatment of certain bacterial diseases susceptible to chlortetracycline pre-mixes in calves.

Thereafter, the sponsor complied with the evaluation of NAS/NRC and FDA's conclusions in the following manner:

  1. Appropriate oral doses for all the allowable species and claims based on milligrams per unit of body weight or grams per ton are on the current labels.
  2. Each disease claim on the label has been properly qualified with the approriate genus and species of bacteria susceptible to chlortetracycline hydrochloride. Disease claims which were not so qualified have been deleted.
  3. Claims made for prevention have been revised to read "Control of..." where appropriate.
  4. Claims for growth promotion or stimulation have been removed. Allowable claims are for increased rate of weight gain and improved feed effieciency.


No further safety data are required.


The NAS/NRC evaluation of the drug is concerned only with the effectiveness and safety of the drug for the treated animal. FDA's approval of the supplemental application does not involve reevaluation or reaffirmation of the human food safety data in the parent application. The tolerances for residues of chlortetracycline are codified at 21 CFR 556.150.


This supplemental NADA satisfies the requirements of section 512 of the Act and demonstrates that Chlortetracycline Type A Medicated Article Milk Replacer when used under its proposed conditions of use, is safe and effective for the labeled indications. The approval provides for use of ChlortetracyclineType A Medicated Article Milk Replaccer for the control and treatment of specific diseases in calves.

The "probably effective" finding of the NAS/NRC regarding chlotetracycline hydrochloride which was published in the FEDERAL REGISTER of July 21, 1970, was subsequently reviewed by FDA, resulting in the upgrade to "effective" status with respect to the claims noted in the paragraphs aabove. The firm submitted revised labeling to conform and, therefore, this supplemental NADA complies with the NAS/NRC evaluation and FDA's conclusions.

When NADA 92-287 was reviewed under NAS/NRC/DESI program, it was an over-the-counter product and this marketing status remains unchanged. Other Chlortetracycline Type A Medicated Articles (milk replacer) for use in food-producing animals (calves) are also currently on the market as over-the-counter products. Therefore, the Center for Veterinary Medicine has concluded that this product should retain over-the-counter marketing status.

Under the Center's supplemental approval policy (21 CFR 514.106(b)(2)), this is a Category II change. The approval of this change is not expected to have any adverse effect on the safety or effectiveness of this new animal drug and, therefore, did not require a reevaluation of the human food or target animal safety data in the parent application.

Under the Generic Animal Drug and Patent Term Restoration Act of 1988, this approval does not qualify for an exclusivity period under section 512(c)(2)(F)(iii) of the Federal, Food, Drug, and Cosmetic Act (21 U.S.C. 360b (c)(2)(F)(iii)) because the supplemental application does not contain reports of new clinical or field investigations (other than bioequivalence or residue studies) and in the case of food producing animals human food safety studies (other than bioequivalency or residue studies) essential to the approval and conducted or sponsored by the applicant.


CLTC 50 MR and CLTC 100 MR 25 pounds and 100 pounds bags

Copies of applicable labels may be obtained by writing to the:

Food and Drug Administration
Freedom of Information Staff (HFI-35)
5600 Fishers Lane
Rockville, MD 20857

Or requests may be sent via fax to: (301) 443-1726. If there are problems sending a fax, call (301) 443-2414.