21 CFR § 520.90a - Ampicillin tablets.

---
identifier: "/us/cfr/t21/s520.90a"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "21 CFR § 520.90a - Ampicillin tablets."
title_number: 21
title_name: "Food and Drugs"
section_number: "520.90a"
section_name: "Ampicillin 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"
---


# 520.90a Ampicillin tablets.

(a) *Specifications.* Each tablet contains ampicillin trihydrate equivalent to 50 or 100 milligrams of ampicillin.

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

(c) *Conditions of use in dogs*—(1) *Amount.* 5 milligrams per pound of body weight, at 8-hour intervals, 1 to 2 hours prior to feeding, to be continued 36 to 48 hours after all symptoms have subsided. If no improvement is seen within 5 days, stop treatment, reevaluate diagnosis, and change therapy.

(2) *Indications for use.* Oral treatment of infections caused by susceptible organisms as follows: Upper respiratory infections, tonsillitis, and bronchitis due to *Streptococcus* spp., *Staphylococcus* spp., *Escherichia coli, Proteus mirabilis,* and *Pasteurella* spp., urinary tract infections (cystitis) due to *Streptococcus* spp., *Staphylococcus* spp., *E., coli, P. mirabilis,* and *Enterococcus* spp.; gastrointestinal infections due to *Staphylococcus* spp., *Streptococcus* spp., *Enterococcus* spp., and *E. coli.* ; infections associated with abscesses, lacerations, and wounds caused by *Staphylococcus* spp., and *Streptococcus* spp.

(3) *Limitations.* Federal law restricts this drug to use by or on the order of a licensed veterinarian.

[57 FR 37321, Aug. 18, 1992, as amended at 60 FR 55659, Nov. 2, 1995; 79 FR 28818, May 20, 2014. Redesignated at 85 FR 18118, Apr. 1, 2020]