1.3 USP <797> Categories 1, 2, and 3 CSP Classification

1.3 USP <797> Categories 1, 2, and 3 CSP Classification

The Paradigm Shift: Why Legacy Risk Levels Were Replaced

Under the 2008 edition of USP <797>, compounding risk was stratified based on subjective operational complexity:

• Low-risk level: ≤ 3 commercially manufactured sterile packages and ≤ 2 entries into any single container.
• Medium-risk level: Multiple individual or small doses pooled, complex manipulations, or prolonged compounding duration (e.g., automated total parenteral nutrition [TPN] batching).
• High-risk level: Utilizing non-sterile starting ingredients, non-sterile bulk chemical powders, or open-air exposure of sterile components.

This legacy taxonomy exhibited significant regulatory and microbiological flaws. It conflated facility engineering quality with compounding manipulation counts, failed to establish clear analytical thresholds for extended storage, and introduced substantial ambiguity regarding segregated compounding areas. The 2023 revision discarded this subjective framework in favor of three objective categories defined by the physical environment, component sterility, release testing, and monitoring frequency.

Category 1 Compounded Sterile Preparations

Category 1 CSPs are formulated to accommodate rapid clinical deployment in environments lacking a classified cleanroom suite, such as hospital satellite pharmacies, emergency department compounding rooms, outpatient oncology clinics, and ambulatory surgical centers.

Environmental & Engineering Specifications:

• Primary Engineering Control (PEC): Must be compounded inside an ISO Class 5 PEC (such as a Laminar Airflow Workbench [LAFW], Class II Biological Safety Cabinet [BSC], or Compounding Aseptic Isolator [CAI]).
• Secondary Engineering Control (SEC): May be located inside an unclassified Segregated Compounding Area (SCA) or within a certified cleanroom suite. The SCA must have a defined perimeter and must be dedicated to compounding. It must be located away from unsealed windows, doors to the outdoors, and traffic flow, and it cannot sit where restrooms, warehouses, or food preparation areas threaten air quality. Any hand-washing sink must be at least 1 meter from the PEC.
• Starting Components: May utilize sterile commercial products or non-sterile bulk chemicals. If non-sterile components are used, the preparation must be sterilized (e.g., by sterilizing filtration or terminal sterilization). Whatever the starting components, a CSP compounded in an SCA stays within the Category 1 BUD limits.

Beyond-Use Dating (BUD) Ceilings for Category 1:

• Controlled Room Temperature (20°C to 25°C): Maximum 12 hours.
• Refrigerated Storage (2°C to 8°C): Maximum 24 hours.
• Frozen Storage (-25°C to -10°C): Prohibited (Category 1 CSPs can never be frozen).

Category 2 Compounded Sterile Preparations

Category 2 represents standard cleanroom sterile compounding, comprising the vast majority of daily parenteral admixtures prepared in institutional health-system cleanrooms and centralized compounding pharmacies.

Environmental & Engineering Specifications:

• Secondary Engineering Control (SEC): Must be prepared in a certified cleanroom suite consisting of:
  • An ISO Class 5 PEC.
  • Located inside an ISO Class 7 positive-pressure buffer room (or negative pressure for hazardous compounding under USP <800>).
  • Supported by an ante-room providing ISO Class 7 air (if opening into a negative-pressure buffer room) or ISO Class 8 air (if opening into a positive-pressure buffer room).
  • Isolator placement: A CAI or CACI is a restricted-access barrier system (RABS). If it is used for Category 2, it must sit inside a cleanroom suite with an ISO Class 7 or better buffer room and an ISO Class 8 or better anteroom. The 2008 exemption that let CAIs outside a cleanroom earn longer dating is gone. Only a pharmaceutical isolator, which has its own decontamination system, may be placed in an ISO Class 8 or better room without a separate anteroom. A CAI or CACI in unclassified space is treated as an SCA and limited to Category 1.
• Starting Components: Sterile commercial products (sterile-to-sterile) OR non-sterile bulk active pharmaceutical ingredients (APIs) and raw excipients.
• Sterilization Protocols: When using non-sterile components, the preparation must undergo validated terminal sterilization (e.g., saturated steam autoclave cycle) or sterilizing filtration using a certified sterile 0.22-micron membrane filter accompanied by post-filtration bubble-point integrity testing.

Beyond-Use Dating Framework for Category 2:

Category 2 BUDs are governed by four distinct parameters: starting material sterility, sterilization method, sterility release testing status, and storage temperature.

Category 3 Compounded Sterile Preparations

Category 3 represents advanced, highly regulated compounding designed for facilities requiring extended beyond-use dating—up to 60, 90, or 120 days—to support batch manufacturing, regional health-system distribution networks, or home infusion therapies.

Mandatory Prerequisites for Category 3 Compounding:

1. Cleanroom Suite Mandate: Category 3 CSPs must be compounded in a cleanroom suite, or in a pharmaceutical isolator placed in an ISO Class 8 or better room. They can never be made in an unclassified Segregated Compounding Area (SCA).
2. Garbing: In the buffer room where Category 3 CSPs are made, no skin may be exposed, so the face and neck are covered. All low-lint outer garb must be sterile, including sterile sleeves over RABS gauntlets. Disposable garb is not reused, and laundered garb must be relaundered and resterilized with a validated cycle before reuse. Goggles and respirators do not have to be sterile, but the SOPs must describe how they are disinfected. These rules apply in that buffer room at all times, even on days when no Category 3 CSP is made.
3. Personnel Competency Cadence: Garbing competency (visual observation plus gloved fingertip and thumb sampling) and aseptic manipulation competency (media fill, gloved fingertip sampling, and surface sampling of the direct compounding area) are repeated at least every 3 months, instead of every 6 months for Categories 1 and 2.
4. Environmental Monitoring Frequency:

• Viable air sampling of all classified areas within 30 days before Category 3 compounding starts and at least monthly afterward, compared with every 6 months for Categories 1 and 2.
• Surface sampling of all classified areas and pass-through chambers at least weekly, and before any Category 3 BUD is assigned.
• Surface sampling inside the PEC at the end of each batch, before cleaning and disinfection. For a self-enclosed robotic device, it is done at least daily at the end of operations.

1. Sporicidal Disinfection: A sporicidal disinfectant is applied at least weekly, compared with monthly for Categories 1 and 2.
2. Stability Data: The BUD must be supported by stability data from a stability-indicating analytical method, meaning one that separates the drug from its degradants and impurities. The data may come from a published or unpublished study, as long as the formulation (ingredients of identical grade and procedure) and the container-closure materials are exactly the same. The study does not need to be repeated for each batch.
3. Release Sterility and Endotoxin Testing: Every Category 3 batch is sterility tested per USP <71>, or by a validated alternative method per USP <1223>. Any CSP requiring sterility testing is capped at 250 final yield units per batch. Injectable Category 3 CSPs made from any nonsterile component must also pass bacterial endotoxin testing per USP <85>.
4. Maximum Category 3 BUD Ceilings:

• Aseptically prepared: 60 days controlled room temp, 90 days refrigerated, 120 days frozen.
• Terminally sterilized: 90 days controlled room temp, 120 days refrigerated, 180 days frozen.

Master Comparison Table: Categories 1, 2, and 3 CSPs

Personnel Competency and Re-Qualification Protocols

Personnel qualification represents a major pillar of sterility assurance under USP <797>. Personnel competency is assessed via two objective microbiological simulations:

1. Gloved Fingertip and Thumb Sampling (GFT): Evaluates garbing competency and hand hygiene. Both hands are sampled onto contact agar plates containing neutralizing agents immediately after garbing.
   • Initial Qualification: Compounding personnel must successfully complete three consecutive GFT evaluations with 0 Colony Forming Units (CFU) for both hands combined.
   • Ongoing garbing competency: The visual observation plus GFT after garbing repeats at least every 6 months for Category 1 and 2 compounders and every 3 months for Category 3. The action level is still > 0 CFU. The > 3 CFU action level (both hands combined) applies only to the GFT taken inside the PEC right after a media-fill test.
2. Media-Fill Testing (MFT): Simulates the most challenging compounding manipulations using sterile microbiological growth medium (e.g., Soybean-Casein Digest Medium / Tryptic Soy Broth [TSB]). Units are incubated for at least 7 days at 20°C to 25°C and at least 7 days at 30°C to 35°C, in an order the facility's SOPs specify. Any turbidity is a failure. The aseptic manipulation competency also includes a GFT inside the PEC (action level > 3 CFU) and surface sampling of the direct compounding area. Failing any one of the three fails the whole evaluation.

Operational Decision Algorithm for CSP Classification

When a sterile compounding workflow is designed, pharmacists must apply a systematic decision hierarchy:

1. Step 1: Physical Environment: Is the PEC situated in an unclassified Segregated Compounding Area (SCA)?
   • If YES: The preparation is automatically designated as Category 1. Maximum BUD is 12 hours room temperature or 24 hours refrigerated.
   • If NO (it is in a certified cleanroom suite): Proceed to Step 2.
2. Step 2: BUD Duration Requirement: Does the required beyond-use dating exceed standard Category 2 parameters (e.g., > 10 days refrigerated for sterile-to-sterile without sterility testing, or > 45 days refrigerated with sterility testing)?
   • If NO: Compound under Category 2 standards.
   • If YES: Proceed to Step 3.
3. Step 3: Category 3 Prerequisite Audit: Has the facility fulfilled every Category 3 mandate?
   • Quarterly garbing and aseptic manipulation competency for every Category 3 compounder?
   • Monthly viable air sampling, weekly surface sampling, and PEC surface sampling after each batch?
   • Weekly sporicidal disinfection?
   • No exposed skin and sterile outer garb in the Category 3 buffer room at all times?
   • Stability-indicating data for the exact formulation and container-closure system?
   • Sterility testing of every batch (250 units maximum), plus endotoxin testing for injectables made from nonsterile components?
   • If YES to all: May compound and release as Category 3.
   • If NO to any single parameter: The preparation cannot be assigned a Category 3 BUD and must be restricted to Category 2 dating.