21 CFR § 520.2330 - Sulfisoxazole tablets.

---
identifier: "/us/cfr/t21/s520.2330"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "21 CFR § 520.2330 - Sulfisoxazole tablets."
title_number: 21
title_name: "Food and Drugs"
section_number: "520.2330"
section_name: "Sulfisoxazole tablets."
chapter_name: "FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES"
subchapter_number: "E"
subchapter_name: "ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS"
part_number: "520"
part_name: "ORAL DOSAGE FORM NEW ANIMAL DRUGS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "21 U.S.C. 360b."
regulatory_source: "40 FR 13838, Mar. 27, 1975, unless otherwise noted."
cfr_part: "520"
---


# 520.2330 Sulfisoxazole tablets.

(a) *Specifications.* Each tablet contains 260 milligrams (4 grains) of sulfisoxazole.

(b) *Sponsor.* See No. 054771 in § 510.600(c) of this chapter.

(c) *Conditions of use*—(1) *Amount.* Administer one tablet orally per 4 pounds of body weight.

(2) *Indications for use.* Use in dogs and cats as an aid in treatment of bacterial pneumonia and bacterial enteritis when caused by organisms sensitive to sulfisoxazole.

(3) *Limitations.* Repeat dosage at 24-hour intervals until 2 to 3 days after disappearance of clinical symptoms. (Administration of one-half daily dosage at 12-hour intervals or one-third daily dosage at 8-hour intervals will provide a more constant blood level.) Provide adequate supply of drinking water. If symptoms persist after using this preparation for 2 or 3 days, consult a veterinarian. Federal law restricts this drug to use by or on the order of a licensed veterinarian.

[43 FR 60895, Dec. 29, 1978, as amended at 79 FR 28831, May 20, 2014; 87 FR 76421, Dec. 14, 2022]