21 CFR § 520.2382 - Thiabendazole and triclorfon.

---
identifier: "/us/cfr/t21/s520.2382"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "21 CFR § 520.2382 - Thiabendazole and triclorfon."
title_number: 21
title_name: "Food and Drugs"
section_number: "520.2382"
section_name: "Thiabendazole and triclorfon."
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"
---


# 520.2382 Thiabendazole and triclorfon.

(a) *Specifications.* The drug contains 5 grams of thiabendazole with 4.5 grams of trichlorfon, or 20 grams of thiabendazole with 18 grams of trichlorfon.

(b) *Sponsor.* See No. 017135 in § 510.600(c) of this chapter.

(c) *Conditions of use in horses*—(1) *Amount.* Administer 2 grams of thiabendazole with 1.8 grams of trichlorfon per 100 pounds of body weight sprinkled on the animals' usual daily ration of feed, or may be mixed in 5 to 10 fluid ounces of water and administered by stomach tube or drench.

(2) *Indications for use.* For the treatment and control of bots (*Gasterophilus* spp.), large strongyles (*Strongylus* spp.), small strongyles (genera *Cyathostomum, Cylicobrachytus,* *Craterostomum, Oesophagodontus,* *Poteriostomum*), pinworms (*Oxyuris* spp., *Strongyloides* spp.), and ascarids (*Parascaris* spp.).

(3) *Limitations.* Do not use in horses intended for human consumption. Federal law restricts this drug to use by or on the order of a licensed veterinarian.

[40 FR 23071, May 28, 1975, as amended at 48 FR 48229, Oct. 18, 1983; 79 FR 28832, May 20, 2014. Redesignated at 84 FR 39183, Aug. 9, 2019. Redesignated at 88 FR 27699, May 3, 2023]