---
kind: "section"
citation: "21 C.F.R. § 331.21"
title: "21"
number: "331.21"
heading: "Test modifications."
url: "https://uscodex.org/cfr/21/331.21"
---

# §331.21. Test modifications.


The formulation or mode of administration of certain products may require a modification of the United States Pharmacopeia 23/National Formulary 18 acid neutralizing capacity test. Any proposed modification and the data to support it shall be submitted as a petition under the rules established in [§ 10.30](/cfr/21/10.30.md) of this chapter. All information submitted will be subject to the disclosure rules in [part 20](/cfr/21/part20.md) of this chapter.


## Notes

### Amendments

[61 FR 4823, Feb. 8, 1996]

### Authority

Authority: 21 U.S.C. 321, 351, 352, 353, 355, 360, 371.

### Source

Source: 39 FR 19874, June 4, 1974, unless otherwise noted.

### Amendments

[61 FR 4823, Feb. 8, 1996]