---
kind: "section"
citation: "21 C.F.R. § 558.555"
title: "21"
number: "558.555"
heading: "Semduramicin."
url: "https://uscodex.org/cfr/21/558.555"
---

# §558.555. Semduramicin.

- (a) **Specifications.** Type A medicated article containing:
  - (1) 22.7 grams (g) per pound (lb) (50 g/kilogram (kg)) semduramicin (as semduramicin sodium).
  - (2) 22.7 g/lb (50 g/kg) semduramicin (as semduramicin sodium biomass).
- (b) **Sponsor.** See No. 066104 in [§ 510.600(c)](/cfr/21/510.600.md?p=c) of this chapter for use of product described in [paragraph (a)(1)](#a-1) of this section as in [paragraph (d)](#d) of this section; for use of product described in [paragraph (a)(2)](#a-2) of this section as in [paragraph (e)](#e) of this section.
- (c) **Related tolerances.** See [§ 556.597](/cfr/21/556.597.md) of this chapter.
- (d) **Conditions of use in chickens.** It is used in chicken feed as follows:
- (e) **Conditions of use in chickens.** It is used in chicken feed as follows:
- (f) Semduramicin may also be used in combination with virginiamycin as in [§ 558.635](/cfr/21/558.635.md).

## Notes

### Amendments

[59 FR 17477, Apr. 13, 1994, as amended at 60 FR 57928, Nov. 24, 1995; 61 FR 29481, June 11, 1996; 61 FR 43451, Aug. 23, 1996; 61 FR 66584, Dec. 18, 1996; 62 FR 66985, Dec. 23, 1997; 64 FR 48296, Sept. 3, 1999; 66 FR 47964, Sept. 17, 2001; 69 FR 13221, Mar. 22, 2004; 70 FR 41961, July 21, 2005; 73 FR 812, Jan. 4, 2008; 74 FR 41631, Aug. 18, 2009; 79 FR 10983, Feb. 27, 2014; 79 FR 13546, Mar. 11, 2014; 81 FR 17609, Mar. 30, 2016; 81 FR 95013, Dec. 27, 2016; 86 FR 14826, Mar. 19, 2021; 87 FR 17948, Mar. 29, 2022]

### Authority

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

### Source

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

### Amendments

[59 FR 17477, Apr. 13, 1994, as amended at 60 FR 57928, Nov. 24, 1995; 61 FR 29481, June 11, 1996; 61 FR 43451, Aug. 23, 1996; 61 FR 66584, Dec. 18, 1996; 62 FR 66985, Dec. 23, 1997; 64 FR 48296, Sept. 3, 1999; 66 FR 47964, Sept. 17, 2001; 69 FR 13221, Mar. 22, 2004; 70 FR 41961, July 21, 2005; 73 FR 812, Jan. 4, 2008; 74 FR 41631, Aug. 18, 2009; 79 FR 10983, Feb. 27, 2014; 79 FR 13546, Mar. 11, 2014; 81 FR 17609, Mar. 30, 2016; 81 FR 95013, Dec. 27, 2016; 86 FR 14826, Mar. 19, 2021; 87 FR 17948, Mar. 29, 2022]