21 CFR § 520.43 - Afoxolaner.

---
identifier: "/us/cfr/t21/s520.43"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "21 CFR § 520.43 - Afoxolaner."
title_number: 21
title_name: "Food and Drugs"
section_number: "520.43"
section_name: "Afoxolaner."
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"
---


# 520.43 Afoxolaner.

(a) *Specifications.* Each chewable tablet contains 11.3, 28.3, 68, or 136 milligrams (mg) afoxolaner.

(b) *Sponsor.* See No. 000010 in § 510.600(c) of this chapter.

(c) *Conditions of use*—(1) *Amount.* Administer orally once a month at a minimum dosage of 1.14 mg/pound (2.5 mg/kilogram).

(2) *Indications for use.* Kills adult fleas and for the treatment and prevention of flea infestations (*Ctenocephalides felis*); and the treatment and control of *Ixodes scapularis* (black-legged tick), *Dermacentor variabilis* (American dog tick), *Amblyomma americanum* (lone star tick), *Rhipicephalus sanguineus* (brown dog tick), and *Haemaphysalis longicornis* (longhorned tick) infestations in dogs and puppies 8 weeks of age and older, weighing 4 pounds of body weight or greater, for 1 month; and for the prevention of *Borrelia burgdorferi* infections as a direct result of killing *Ixodes scapularis* vector ticks.

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

[78 FR 66264, Nov. 5, 2013, as amended at 79 FR 37619, July 2, 2014; 84 FR 8972, Mar. 13, 2019; 84 FR 39182, Aug. 9, 2019; 88 FR 55563, Aug. 16, 2023]