Compliance with the USP–NF
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) 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.
USP scientists cannot review and interpret data, per the Official Statements and Interpretations policy (http://www.usp.org/about-usp/leadership/policies-rules/code-ethics/standards-setting-processes): “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.”
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 18.104.22.168 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."
The specifications in the Description and Solubility section of the compendium are not considered official requirements by the USP. Within this section it states, "The `description’ and `solubility’ statements pertaining to an article (formerly included in the individual monograph) are general in nature. The information is provided for those who use, prepare, and dispense drugs, solely to indicate descriptive and solubility properties of an article complying with monograph standards. The properties are not in themselves standards or tests for purity even though they may indirectly assist in the preliminary evaluation of the integrity of an article." (See also General Notices, section 5.30.)