d Trichlorfon, phenothiazine, and piperazine.
21 C.F.R. § 520.2520d
in effectEffective: 2024-07-01(a) Specifications. Each 54.10 grams (1.91 ounces) of water dispersible powder contains 9.10 grams of trichlorfon, 6.25 grams of phenothiazine, and the equivalent of 20.0 grams of piperazine base (as piperazine dihydrochloride).
(b) Sponsor. See No. 054771 in § 510.600(c) of this chapter.
(c) Conditions of use in horses—(1) Amount. 18.2 milligrams (mg) of trichlorfon, 12.5 mg of phenothiazine, and 40 mg of piperazine base per pound of body weight.
(2) Indications for use. For removal of bots (Gastrophilus nasalis, Gastrophilus intestinalis), large strongyles (Strongylus vulgaris), small strongyles, large roundworms (ascarids, Parascaris equorum), and pinworms (Oxyuris equi).
(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.
Source: eCFRURL: https://www.ecfr.gov/api/versioner/v1/full/2024-07-01/title-21.xmlFetched: 7/26/2026