What USP 797 actually requires

USP General Chapter <797> is a process standard. It governs the air a compounded sterile preparation is made in, the garbing and qualification of the personnel who make it, the monitoring proving the space stayed in spec, and the maximum beyond-use date it may carry. That is the whole of it. It does not certify what is in the vial, how pure that material is, or that any agency reviewed it before it shipped. Reading "compounded to USP <797>" correctly means holding both halves at once: the contamination control it guarantees, and the larger set of questions it was never written to answer.

What USP 797 actually covers

The current chapter was published 1 November 2022 and became official 1 November 2023, replacing a version that had stood since 2008. The most consequential change is structural: the old low-, medium-, and high-risk levels are gone. Many supplier pages still describe them — a quick tell that a document is stale.

In their place are three categories of compounded sterile preparation, defined not by how complex the manipulation was but by where it was made and what testing it received:

• Category 1 — made in a segregated compounding area, an ISO Class 5 PEC sited in an otherwise unclassified room rather than a classified suite. Entirely permitted, and priced in with the shortest beyond-use dates.
• Category 2 — compounded in a classified cleanroom suite. Permitted dating varies with starting components, sterilization method, and whether the preparation passed a sterility test.
• Category 3 — new in the current revision. Longest permitted dating, conditional on additional garbing, sterility and bacterial endotoxin testing, more frequent monitoring, and documented stability data.

The chapter also governs SOPs, master formulation and compounding records, component handling, sterilization, quality assurance, and recalls. Hazardous drugs add containment requirements under USP <800>.

ISO-classified air and primary engineering controls

Air cleanliness is defined by ISO 14644-1, which ranks a space by the maximum airborne particles permitted per cubic meter above a given size. The primary engineering control (PEC) — a laminar airflow workbench, biological safety cabinet, compounding aseptic isolator, or restricted-access barrier system — provides ISO Class 5 air over exposed critical sites.

Space	Class	Max particles ≥0.5 µm per m³	Function
Direct compounding area, inside the PEC	ISO 5	3,520	Critical sites exposed
Buffer room	ISO 7	352,000	Houses the PEC
Ante-room (non-hazardous, positive pressure)	ISO 8	3,520,000	Garbing, staging

"ISO Class 5 cleanroom" is a common misnomer: ISO Class 5 describes the air inside the engineering control, not the room, which is ISO Class 7. A classified suite must supply at least 30 air changes per hour of HEPA-filtered air and hold a pressure differential of at least 0.020 inches of water column between buffer room and ante-room. Every PEC and classified room must be certified at least every six months.

Garbing and competency qualification

The chapter treats personnel as the dominant contamination vector. It specifies the required garb — shoe covers, head and facial hair covers, face mask, low-lint gown, sterile powder-free gloves — plus hand hygiene, an alcohol-based antiseptic, and glove disinfection with sterile 70% isopropyl alcohol at defined intervals during compounding.

Qualification is where the standard has teeth. Before compounding independently, personnel must pass garbing and gloving competency verified by gloved fingertip and thumb sampling — three successful consecutive evaluations — and a media-fill test, in which growth medium replaces the drug through the full compounding sequence. If the medium stays clear after incubation, aseptic technique held. Requalification is required at least every six months for Category 1 and 2 personnel, every three months for Category 3.

A passing media fill demonstrates that one operator, on one day, did not introduce viable organisms. It says nothing about the chemistry of the substance handled.

Environmental monitoring and its blind spots

Viable air sampling is required at least every six months for Category 1 and 2 and at least monthly for Category 3; surface sampling at least monthly, more often for Category 3; non-viable particle counts accompany the semiannual certification. Recovered colonies are counted against viable air action levels — broadly, more than 1 CFU per cubic meter in ISO Class 5, more than 10 in ISO Class 7, more than 100 in ISO Class 8 — and exceeding one triggers investigation and organism identification, not automatic rejection.

The blind spot is frequency. A suite certified in January and air-sampled in June has months of operation between data points. That is not a criticism of a chapter written to control process risk economically; it is why lot-level analysis complements <797>. Environmental data describes the room over time. A certificate of analysis describes the material in front of you.

How the chapter assigns beyond-use dating

A beyond-use date is not an expiration date. Expiration dates come from formal stability programs. A <797> beyond-use date is a contamination-risk ceiling set by how and where the preparation was made: stability data can shorten it, but cannot lengthen it past the chapter's limit. Storage conditions are those in USP <659>: controlled room temperature 20–25 °C, refrigerated 2–8 °C, frozen −25 to −10 °C.

Category and conditions	Room temp.	Refrigerated	Frozen
Category 1	12 hours	24 hours	Not assigned
Category 2 — aseptic, any non-sterile component, no sterility test	1 day	4 days	45 days
Category 2 — aseptic, all sterile components, no sterility test	4 days	10 days	45 days
Category 2 — terminally sterilized, no sterility test	14 days	28 days	45 days
Category 2 — aseptic, passing sterility test	30 days	45 days	60 days
Category 2 — terminally sterilized, passing sterility test	45 days	60 days	90 days
Category 3 — aseptic, passing sterility test, all conditions met	60 days	90 days	120 days

Two things follow. A refrigerated beyond-use date means nothing if those conditions did not hold, which is why what happens between facility and bench belongs to the same argument. And solid and solution presentations rest on different data: a freeze-dried cake's shelf life comes from solid-state stability work, while the table above caps preparations in solution. Diluents are sterile preparations in their own right — bacteriostatic water carries its own release testing.

What "compounded to USP <797>" does not mean

• It is not FDA approval. USP is a non-governmental standards-setting organization. Compounded preparations are not FDA-approved, and FDA does not review them for safety or effectiveness. The chapter's force comes from state boards adopting it and from references in federal law.
• It is not a purity or potency claim. <797> governs contamination control. It does not require a finished lot to be assayed for identity, potency, or related-substance profile. Chromatographic purity and mass-spectrometric identity are separate determinations.
• It is not a per-unit sterility guarantee. Outside preparations that undergo sterility testing, sterility is inferred from process control — and sterility testing is destructive and statistical, sampling only a fraction of the lot.
• It is not CGMP. Meeting <797> does not establish compliance with current good manufacturing practice — a distinction FDA draws in its January 2020 final guidance on CGMP for outsourcing facilities compounding under section 503B.

503A vs 503B, in plain language

Both exist under the Federal Food, Drug, and Cosmetic Act. Section 503B was added by the Drug Quality and Security Act (Pub. L. 113-54, 2013), passed after a 2012 outbreak of fungal infections traced to contaminated injections from one compounding pharmacy.

Dimension	503A compounding pharmacy	503B outsourcing facility
Statute	FD&C Act §503A (21 U.S.C. 353a)	FD&C Act §503B (21 U.S.C. 353b)
Trigger to compound	Patient-specific prescription; limited anticipatory compounding	May compound without patient-specific prescriptions
Primary oversight	State board of pharmacy	Registers with FDA; risk-based inspection
Production standard	USP <797> as adopted by the state	CGMP (21 CFR parts 210 and 211)
Bulk drug substances	USP/NF monograph, component of an approved drug, or FDA's 503A bulks list	On FDA's 503B bulks list or the shortage list
Distribution	Dispensed to an identified patient	May distribute as office stock
Adverse event reporting	Not federally required	Required; biannual product reporting

Neither produces an FDA-approved drug product, and both are barred from compounding what the statute calls "essentially a copy" of a commercially available drug, under definitions that differ between the sections.

<797> and lot-level analysis answer different questions; a supplier offering only one has answered half of them. Merit's compounds are produced in an ISO-certified US facility compounding to USP <797>, and every lot ships with a certificate of analysis reporting HPLC purity, mass-spectrometric identity, and endotoxin results for that lot, retrievable by the lot number on the vial through the certificate lookup. Read "compounded to USP <797>" as a claim about environment and process discipline — real, and worth having — then ask what the chapter cannot answer: what does the analytical data say about this lot?

For research use only. This article describes a compendial standard and applicable federal law; it is interpretive summary, not regulatory advice, and not guidance for handling or preparing any material.