Animal & Veterinary

ANADA 200-126 PHENYLBUTAZONE 20% INJECTION - original approval

Approval Date: September 1, 1995





Phoenix Scientific, Inc.
3915 S. 48th St. Terrace
P.O. Box 6457
St. Joseph, MO 64506-0457

Generic Name:

phenylbutazone, USP

Trade Name:


Marketing Status:



For relief of inflammatory conditions associated with the musculoskeletal system in horses.







Intravenous injection



Horses: 1 to 2 g per 1000 lb body weight (5 to 10 mL/1000 lb) daily for a maximum of 5 days.

Intravenous treatment may be followed by oral phenylbutazone dosage forms.


Under the provisions of the Federal Food, Drug, and Cosmetic Act, as amended by the Generic Animal Drug and Patent Term Restoration Act (53 FR 50460, December 15, 1988; first GADPTRA Policy Letter), an Abbreviated New Animal Drug Application (ANADA) may be submitted for a generic version of an approved new animal drug (pioneer product). For certain dosage forms, the Agency grants a waiver from conducting an in vivo bioequivalence study (55 FR 24645, June 18, 1990; fifth GADPTRA Policy Letter). In lieu of bioequivalence testing, the safety and efficacy of the generic product are based on the demonstrated chemical equivalence to the pioneer product.

Based on the formulation characteristics of the generic product, Phoenix Scientific, Inc. was granted a waiver April 15, 1992 (see Section 4) from conducting an in vivo bioequivalence study with Phenylbutazone 20% Injection. The generic and pioneer products are solutions with the same concentrations of active and inactive ingredients.


Human Safety Relative to Food Consumption:
Regarding consumption of drug residues in food, human safety data were not required for approval of this ANADA. This drug is labeled for use in horses not intended for food.

Human Safety Relative to Possession, Handling and Administration:
Labeling contains adequate caution/warning statements.


INAD 8350 (C001)

James H. Schafer, D.V.M.
Consultant to the Veterinary
Pharmaceutical Industry
Ft. Collins, CO 80524

Dear Dr. Schafer:

We refer to your submission dated March 3, 1992, to the Investigational New Animal Drug (INAD) file on the behalf of Phonix Pharmaceutical, Inc. for a generic copy of Coopers Animal Health Incorporated's Butazolidin (phenylbutazone, 200 mg/mL, NADA 011-575). The product is proposed for relief of inflammatory conditions associated with the musculoskeletal system in dogs and horses. You requested a waiver of the requirement for an in vivo bioequivalence study to support the filing of an Abbrevieated New Animal Drug Application (ANADA) based on the Generic Animal Drug and Patent Term Restoration Act (GADPTRA) of 1988.

Based on the information you provided, your proposed product contains the same active and inactive ingredients in the same concentrations as the approved pioneer product. The pH of your product conforms to that of the pioneer, and the route of administration is the same. It is, therefore, eligible for a waiver from in vivo bioequivalence testing under our current policy.

Your request for a waiver is granted on the condition that the full information presented in your ANADA continues to show that your proposed generic product is chemically equivalent to the pioneer product. If it is not shown to be chemically equivalent, in vivo bioequivalence testing could be required.

Granting of this waiver does not assure approval of you ANADA. All necessary requirements must be fulfilled, including certification that your product or its proposed uses do not violate or infringe upon any patent or exclusivity for the pioneer product or its uses.

Future correspondence to your INAD file regarding this submission should be identified by the date of this letter and our file number, INAD 8350-C001.

In submitting your ANADA, please refer to this number and include a copy of this correspondence in your original submission.

Environmental Considerations:

Your request for a waiver of the bioequivalency test was reviewed under the National Environmental Policy Act (NEPA). Since no investigation is planned under your INAD, no wastes are expected to enter the environment. Therefore, we have determined that this action qualifies for a categorical exclusion from the requirement to prepare an environmental assessment (EA) under 21 CFR 25.24(d)(4). If studies are planned to be conducted under this INAD, please file either a claim for an exclusion or submit and EA.

All ANADAs require an abbbreviated EA. Guidance is available on the preparation of the EA in the Center's second generic animal drug policy letter dated June 7, 1989. The letter contains an example format for preparing an EA for submission tothe ANADA.

Should you have questions or need further assistance, please contact Dr. Sandra K. Woods, Chief of Equine & antimicrobial Drugs Branch. The telephone number is (301) 295-8617.

Sincerely yours,

Bob G. Griffith, DVM
Director, Division of Therapeutic
Drugs for Non-Food Animals
New Animal Drug Evaluation
Center for Veterinary Medicine


This is an Abbreviated New Animal Drug Application (ANADA) filed under Section 512(b)(2) of the Federal, Food, Drug and Cosmetic (FFD&C) Act.

Safety and effectiveness for this generic animal drug, Phenylbutazone 20% Injection (200 mg/mL), were established by demonstration of chemical equivalence to the pioneer product, Cooper's Butazolidin® Injectable, 20% (NADA 011-575).

This generic product and the pioneer product have identical labeling indications for the 100 mL vial for use in horses. The route and method of administration of the two drugs are identical. Both drugs are administered intravenously. The generic and pioneer products contain the same active and inactive ingredients. Therefore, in compliance with FDA policy promulgated to implement Section 512(b)(2) of the FFD&C Act, no additional safety, efficacy, or in vivo bioequivalency studies were necessary or required.

The pioneer package insert includes recommendations for the drug's use in horses and dogs. The generic product is labeled for use in horses only. Under NADA #011-575, the pioneer equine only injectable product is packaged in 100 mL vials. These vials are labeled for use in horses only because the Center for Veterinary Medicine's "Points to Consider in Determining Vial Size for Veterinary Parenteral Products" (1986) indicates that the 100 mL vial for phenylbutazone would not be suitable for use in dogs due to the large number of potential needle punctures in the vial stopper, and resulting stability/sterility concerns. The pioneer also manufactured 25 and 50 mL size vials labeled for horses and dogs (vial sizes suitable for both species). Both species shared the same package insert.

The generic product copies only the 100 mL vial size. Therefore, it can only be labeled for use in horses due to the regulatory decision concerning vial size and sterility issues.

Injectable phenylbutazone has been designated by the Center for Veterinary Medicine as a medically necessary medical drug product. A product shortage currently exists for the injectable formulation.

This ANADA satisfies the requirements of section 512 of the Act and demonstrates that Phenylbutazone 20% Injection, is safe and effective for its labeled indications when used under its proposed conditions of use.


  1. Photocopy of Waiver Letter.
  2. Generic Labeling:
    • package insert (horses only)
    • immediate container label
    • shipper label
  3. Pioneer Labeling:
    • package insert (dogs and horses)
    • immediate container label
    • carton label

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.

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