21 CFR § 520.1284 - Liothyronine.

---
identifier: "/us/cfr/t21/s520.1284"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "21 CFR § 520.1284 - Liothyronine."
title_number: 21
title_name: "Food and Drugs"
section_number: "520.1284"
section_name: "Liothyronine."
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"
---


# 520.1284 Liothyronine.

(a) *Specifications.* Each tablet contains 60 or 120 micrograms (µg) liothyronine as the sodium salt.

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

(c) *Conditions of use in dogs*—(1) *Amount.* Administer orally to dogs at levels up to 12.8 µg per kilogram (/kg) of body weight per day. Dosage should be adjusted according to the severity of the condition and the response of the patient. Dosage at the total replacement level (12.8 µg/kg of body weight) should be considered for initiating therapy and then titrated downward for optimum maintenance effect. Twice daily administration is recommended.

(2) *Indications for use.* For treatment of hypothyroidism in dogs.

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

[78 FR 28823, May 20, 2014]