Skip to Content

Phenylzone Paste

This page contains information on Phenylzone Paste for veterinary use.
The information provided typically includes the following:
  • Phenylzone Paste Indications
  • Warnings and cautions for Phenylzone Paste
  • Direction and dosage information for Phenylzone Paste

Phenylzone Paste

This treatment applies to the following species:
Manufacturer: Intervet/Merck Animal Health



NADA #116-087, Approved by FDA.


PHENYLZONE Paste is a synthetic, nonhormonal, anti-inflammatory, antipyretic compound useful in the management of inflammatory conditions. The apparent analgesic effect is probably related mainly to the compound’s anti-inflammatory properties.

Chemically, phenylbutazone is 4-butyl-1,2-diphenyl-3,5-pyrazolidinedione. It is a pyrazolone derivative, entirely unrelated to the steroid hormones, and has the following structural formula:

Phenylzone Paste Indications:

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


Use with caution in patients who have a history of drug allergy.


Not for use in horses intended for food.


Stop medication at the first sign of gastrointestinal upset, jaundice, or blood dyscrasia. Authenticated cases of agranulocytosis associated with the drug have occurred in man; fatal reactions, although rare, have been reported in dogs after long-term therapy. To guard against this possibility, conduct routine blood counts at weekly intervals during the early phase of therapy and at intervals of 2 weeks thereafter. Any significant fall in the total white count, relative decrease in granulocytes, or black or tarry stools, should be regarded as a signal for immediate cessation of therapy and institution of the appropriate countermeasures.

In the treatment of inflammatory conditions associated with infections, specific anti-infective therapy is required.

ADMINISTRATION AND DOSAGE: Orally - 1 to 2 g of phenylbutazone per 500 lb of body weight, but not to exceed 4 g daily. Use a relatively high dose for the first 48 hours, then reduce gradually to a maintenance dose. Maintain lowest dose capable of producing desired clinical response.

Guidelines to Successful Therapy:

1. Use a relatively high dose for the first 48 hours, then reduce gradually to a maintenance dose. Maintain lowest dose capable of producing desired clinical response.

2. The response to PHENYLZONE therapy is prompt, usually occurring within 24 hours. If no significant clinical response is evident after 5 days, reevaluate diagnosis and therapeutic approach.

3. When administering PHENYLZONE Paste the oral cavity should be empty. Deposit paste on back of tongue by depressing plunger that has been previously set to deliver the correct dose.

4. Many chronic conditions will respond to PHENYLZONE therapy, but discontinuance of treatment may result in recurrence of symptoms.


Store at 15°-30° C (59°-86° F).

How Supplied:

Syringes containing 6 g and 12 g of phenylbutazone, NDC 0061-5045-01

(6 g), NDC 0061-5040-01 (12 g).


Phenylzone Paste Caution:

Federal (U.S.A.) law restricts this drug to use by or on the order of a licensed veterinarian.

Each 1 g marking on the plunger contains:


1 g

Schering-Plough Animal Health

Copyright © 1998, Schering-Plough Animal Health Corp., Union, NJ 07083. All rights reserved. Made in Ireland.



NAC No.: 10471472

Intervet Inc.

Customer Service:   800-521-5767
Order Desk:   800-648-2118
Technical Service (Companion Animal):   800-224-5318
Technical Service (Livestock):   800-211-3573
Fax:   973-937-5557
Every effort has been made to ensure the accuracy of the Phenylzone Paste information published above. However, it remains the responsibility of the readers to familiarize themselves with the product information contained on the US product label or package insert.

Copyright © 2015 North American Compendiums. Updated: 2015-04-03