---
kind: "section"
citation: "21 C.F.R. § 558.575"
title: "21"
number: "558.575"
heading: "Sulfadimethoxine and ormetoprim."
url: "https://uscodex.org/cfr/21/558.575"
---

# §558.575. Sulfadimethoxine and ormetoprim.

- (a) **Specifications.** Type A medicated articles containing either:
  - (1) 25 percent sulfadimethoxine and 15 percent ormetoprim; or
  - (2) 25 percent sulfadimethoxine and 5 percent ormetoprim.
- (b) **Sponsors.** See sponsors in [§ 510.600(c)](/cfr/21/510.600.md?p=c) of this chapter as follows:
  - (1) **No.** 054771 for use of the product described in [paragraph (a)(1)](#a-1) as in paragraphs [(e)(1)](#e-1), (e)(2)(i), and [(e)(3)(i) through (iii)](#e-3-i..e-3-iii) of this section.
  - (2) **No.** 015331 for use of the product described in [paragraph (a)(2)](#a-2) as in paragraphs (e)(3)(iv) and (v) of this section.
- (c) **Related tolerances.** See §§ [556.490](/cfr/21/556.490.md) and [556.640](/cfr/21/556.640.md) of this chapter.
- (d) **Special considerations.**
  - (1) Federal law restricts medicated feed containing this veterinary feed directive (VFD) drug to use by or on the order of a licensed veterinarian. See [§ 558.6](/cfr/21/558.6.md) for additional requirements.
  - (2) The expiration date of VFDs for sulfadimethoxine and ormetoprim medicated feeds must not exceed 6 months from the date of issuance. VFDs for sulfadimethoxine and ormetoprim shall not be refilled.
- (e) **Conditions of use.** It is used in animal feeds as follows:
  - (1) **Chickens—**
  - (2) **Turkeys—**
  - (3) **Minor species—**

## Notes

### Amendments

[40 FR 13959, Mar. 27, 1975, as amended at 42 FR 13550, Mar. 11, 1977; 49 FR 33442, Aug. 23, 1984; 49 FR 46371, Nov. 26, 1984; 51 FR 7400, Mar. 3, 1986; 51 FR 18884, May 23, 1986; 52 FR 2686, Jan. 26, 1987; 54 FR 1686, Jan. 17, 1989; 63 FR 27846, May 21, 1998; 64 FR 26672, May 17, 1999; 64 FR 43910, Aug. 12, 1999; 66 FR 46707, Sept. 7, 2001; 70 FR 52292, Sept. 2, 2005; 79 FR 10983, Feb. 27, 2014; 79 FR 13546, Mar. 11, 2014; 81 FR 95013, Dec. 27, 2016; 83 FR 13637, Mar. 30, 2018; 84 FR 12502, Apr. 2, 2019; 86 FR 14827, Mar. 19, 2021; 87 FR 76424, Dec. 14, 2022; 91 FR 20347, Apr. 16, 2026]

### Authority

Authority: 21 U.S.C. 354, 360b, 360ccc, 360ccc-1, 371.

### Source

Source: 40 FR 13959, Mar. 27, 1975, unless otherwise noted.

### Amendments

[40 FR 13959, Mar. 27, 1975, as amended at 42 FR 13550, Mar. 11, 1977; 49 FR 33442, Aug. 23, 1984; 49 FR 46371, Nov. 26, 1984; 51 FR 7400, Mar. 3, 1986; 51 FR 18884, May 23, 1986; 52 FR 2686, Jan. 26, 1987; 54 FR 1686, Jan. 17, 1989; 63 FR 27846, May 21, 1998; 64 FR 26672, May 17, 1999; 64 FR 43910, Aug. 12, 1999; 66 FR 46707, Sept. 7, 2001; 70 FR 52292, Sept. 2, 2005; 79 FR 10983, Feb. 27, 2014; 79 FR 13546, Mar. 11, 2014; 81 FR 95013, Dec. 27, 2016; 83 FR 13637, Mar. 30, 2018; 84 FR 12502, Apr. 2, 2019; 86 FR 14827, Mar. 19, 2021; 87 FR 76424, Dec. 14, 2022; 91 FR 20347, Apr. 16, 2026]