Glossary
cGMP: the manufacturing regime, and how it differs from a USP chapter
Current good manufacturing practice — cGMP — is the federal manufacturing regime FDA enforces through its own inspections. It is the requirement that separates the two compounding pathways: FDA describes compounding under section 503A as exempt from cGMP. Outsourcing facilities registered under section 503B are subject to it. A USP compounding chapter is a different kind of instrument entirely. USP writes the chapters and enforces nothing; a chapter binds a pharmacy only where a state board of pharmacy adopts a named, dated version by rule, or an accreditor makes it contractual. One is imposed and inspected federally; the other arrives through a state.
What it is, and who it binds
cGMP is the federal manufacturing regime. FDA maps it onto the two compounding pathways in one sentence each, and the pair is the single most-inverted fact in this subject:
Section 503A describes the conditions under which compounded human drug products are exempt from the FD&C Act sections on FDA approval prior to marketing, current good manufacturing practice (CGMP) requirements, and labeling with adequate directions for use.
outsourcing facilities are subject to CGMP requirements … Outsourcing facilities are inspected by FDA according to a risk-based schedule, and must meet certain other conditions, such as reporting adverse events and providing FDA with certain information about the products they compound.
So the regime is FDA’s: imposed by federal regulation and checked by federal inspectors on FDA’s own schedule. It is also the price of one pathway rather than a feature of both — a 503A pharmacy buys its exemption with the patient-specific prescription condition, and a 503B outsourcing facility makes the opposite trade. That is the bargain set out in 503A vs 503B.
New York’s conduct rules show the same split from the state side: a drug is deemed adulterated there if it is not manufactured in accordance with the good manufacturing practices at 21 CFR parts 210 and 211, with a narrow proviso for a pharmacy manufacturing for in-house use.
How it differs from a USP chapter
The two get spoken of as if they were rival grades of the same thing. They are different kinds of instrument, and the difference is who can make them apply to you.
USP describes its own standing in terms that are easy to read past — it says it is "not a government entity" and that it "works closely with government agencies, ministries, and regulatory authorities." Across its compounding chapter pages and its legal-recognition page, USP names no enforcement body at all. A chapter becomes binding through a state board of pharmacy adopting a named, dated version by rule, or through an accreditor whose standards reference it, or — at the ingredient level only — through federal statute.
That gives the two instruments opposite failure modes when someone summarises them. A cGMP claim is checkable against a federal inspection record. A claim to follow USP is checkable against nothing until a chapter number and a state are attached to it, because adoption is version-dated and staggered. What each chapter covers is set out at <795>, <797> and <800>.
What it changes about the date on a label
The clearest downstream consequence is the dating, and it is a difference in the kind of evidence rather than in length. Under the manufacturing regime an expiration date is tied to testing by regulation:
To assure that a drug product meets applicable standards of identity, strength, quality, and purity at the time of use, it shall bear an expiration date determined by appropriate stability testing described in § 211.166.
A preparation compounded under section 503A carries a beyond-use date instead, assigned under the compendial chapter the pharmacy’s state adopted. Two different evidentiary bases, two different words on the label, and no claim here that either one runs longer than the other.