21 CFR § 520.763a - Dithiazanine tablets.

---
identifier: "/us/cfr/t21/s520.763a"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "21 CFR § 520.763a - Dithiazanine tablets."
title_number: 21
title_name: "Food and Drugs"
section_number: "520.763a"
section_name: "Dithiazanine 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"
---


# 520.763a Dithiazanine tablets.

(a) *Specifications.* Each tablet contains 10, 50, 100, or 200 milligrams (mg) dithiazanine iodide.

(b) *Sponsor.* See No. 069043 in § 510.600(c) of this chapter.

(c) *Conditions of use in dogs*—(1) *Indications for use and amount.* Administer orally immediately after feeding as follows:

(i) For large roundworms (*Toxocara canis, Toxascaris leonina*): 10 mg per pound (/lb) of body weight for 3 to 5 days;

(ii) For hookworms (*Ancylostoma caninum, Uncinaria stenocephala*) and whipworms (*Trichuris vulpis*): 10 mg/lb of body weight for 7 days;

(iii) For Strongyloides (*Strongyloides canis, Strongyloides stercoralis*): 10 mg/lb of body weight for 10 to 12 days;

(iv) For heartworm microfilariae (*Dirofilaria immitus*): 3 to 5 mg/lb of body weight for 7 to 10 days. Treatment for heartworm microfilariae should follow 6 weeks after therapy for adult worms.

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

[79 FR 28820, May 20, 2014, as amended at 83 FR 48945, Sept. 28, 2018]