Frequently Asked Questions: Compliance with the USP–NF
- What does compliance with USP–NF standards mean?
- Do all tests specified in a monograph have to be performed to ensure compliance?
- Are adjustments to quantities and concentrations specified in the monograph allowed?
- Must the specifications described in the Description and Solubility section of the USP–NF be met?
- Can a USP scientist review data to confirm that a product complies with the USP requirements?
An article of commerce that is recognized in the USP–NF complies with USP–NF standards when it meets all of the requirements stated in the article’s monograph, applicable General Chapters, and the General Notices (with monograph requirements superseding those of the General Chapters and General Notices, in any cases where requirements differ). Applicable standards apply at all times in the life of an article, from production to expiration. Thus, any official article is expected to meet the compendial standards if tested, and any official article actually tested as directed in the relevant monograph must meet such standards to demonstrate compliance. Frequency of testing and sampling are left to the preferences or direction of those performing compliance testing, and other users of USP–NF, including manufacturers, buyers, or regulatory authorities. (General Notices, section 3.10)
Applicable standards apply at all times in the life of an article, from production to expiration. Thus, any official article is expected to meet the compendial standards if tested, and any official article actually tested as directed in the relevant monograph must meet such standards to demonstrate compliance. A manufacturer’s specifications that have been approved by FDA, and related current good manufacturing practices (GMPs) for drugs and finished pharmaceuticals required by FDA regulations (21 CFR Parts 210, 211), all can help ensure that an article will be in and stay in compliance with compendial standards. As noted in the General Notices (section 3.10), the frequency of any testing and sampling, as well as the necessity and appropriate frequency of any batch testing, are neither specified nor prescribed by the compendia; whether and when to test is left to the preferences or direction of those performing compliance testing, and other users of USP–NF, including manufacturers, buyers, or regulatory authorities.
Some adjustments may be made. In the current USP–NF General Notices section 6.60, the following is stated: "Unless otherwise specified, a sufficient number of units to assure a suitable analytical result shall be taken." Furthermore, section 188.8.131.52 states that "When a specified concentration is called for in a procedure, a solution of other normality or molarity may be used, provided that allowance is made for the difference in concentration and that the change does not increase the error of measurement."
(See also General Notices, section 5.30.)
5.30. Description and Solubility
Only where a quantitative solubility test is given in a monograph and is designated as such is it a test for purity.
A monograph may include information regarding the article's description. Information about an article's “description and solubility” also is provided in the reference table Description and Relative Solubility of USP and NF Articles. The reference table merely denotes the properties of articles that comply with monograph standards. The reference table is intended primarily for those who use, prepare, and dispense drugs and/or related articles. Although the information provided in monographs and the information in the reference table may indirectly assist in the preliminary evaluation of an article, it is not intended to serve as a standard or test for purity.
The approximate solubility of a compendial substance is indicated by one of the following descriptive terms:
Parts of Solvent Required
for 1 Part of Solute
Less than 1
From 1 to 10
From 10 to 30
From 30 to 100
From 100 to 1,000
Very slightly soluble
From 1,000 to 10,000
Practically insoluble, or
Greater than or equal to
USP scientists cannot review and interpret data, per the Official Statements and Interpretations policy: “USP shall not provide an official opinion as to whether a particular article does or does not comply with compendial requirements, except as part of an established USP verification or other conformity assessment program that is conducted separately from and independent of USP's standards-setting activities.”