Mastering USP 797 for CSPT: The Compounding Skills and Cleanroom Procedures You Need to Know to Pass

Mastering USP 797 for CSPT: The Compounding Skills and Cleanroom Procedures You Need to Know to Pass

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Passing the CSPT exam requires more than memorizing facts. It’s about showing you understand how USP <797> protects patients and how to apply that standard at the bench. This guide focuses on what matters most: category definitions and BUDs, garbing and aseptic technique, cleaning and monitoring, documentation, and the small details that the test (and real cleanrooms) use to separate safe practice from risky shortcuts.

What USP <797> Expects: Big Picture

USP <797> sets minimum standards for sterile compounding to prevent microbial contamination, excessive endotoxins, and mix-ups. It defines the rooms, equipment, personnel practices, and quality checks that keep compounded sterile preparations (CSPs) safe. The CSPT exam leans on your ability to apply these rules under pressure—assigning the correct beyond-use date (BUD), choosing the right environment, and executing aseptic technique without contaminating critical sites.

Why this matters: Sterile compounding errors don’t just reduce potency. They can seed infections. Every step—from garbing to labeling—has a safety purpose. The exam tests whether you understand those “whys,” not just the “whats.”

Cleanroom Vocabulary That Shows Up on the Exam

Know these terms cold; they’re the backbone of scenario-based questions.

  • PEC (Primary Engineering Control): ISO Class 5 device that provides unidirectional HEPA-filtered air. Examples: laminar airflow workbench (LAFW), biological safety cabinet (BSC), compounding aseptic isolator (CAI).
  • LAFW: Horizontal (air from back to front) or vertical (top-down) laminar flow. Used for non-hazardous sterile compounding.
  • BSC: Vertical flow; protects product and operator. Used for hazardous compounding per USP <800>.
  • SEC (Secondary Engineering Controls): The cleanroom suite—ante-room and buffer room—surrounding the PEC. Controls room air quality and pressure differentials.
  • Ante-room: Where you garb and stage supplies. Typically ISO 7 or 8 (depending on buffer classification and hazardous vs non-hazardous workflow).
  • Buffer room: Where the PEC sits. ISO 7. Positive pressure for non-HD; negative for HD per <800>.
  • SCA (Segregated Compounding Area): Unclassified space with a PEC and segregation from traffic and sinks. Allows only short BUDs (Category 1).
  • ISO Class: Particle counts in the air. ISO 5 is cleaner than ISO 7; lower number = cleaner air.
  • First air: The clean, HEPA-filtered air with no obstructions. Critical surfaces (needles, vial stoppers) must remain in first air.

Categories and Beyond-Use Dating (BUDs) You Must Memorize

The 2023 revision replaced “low/medium/high risk” with categories based on where the CSP is made and how it is controlled. Your BUD decision starts here.

  • Category 1 CSPs: Compounded in an ISO 5 PEC within an SCA (no cleanroom suite). Short BUDs.
    • Room temperature: ≤ 12 hours
    • Refrigerated: ≤ 24 hours
  • Category 2 CSPs: Compounded in an ISO 5 PEC within an ISO 7 buffer room and appropriate ante-room (a full cleanroom suite). Longer default BUDs (without sterility testing) when prepared from sterile components:
    • Room temperature: ≤ 4 days
    • Refrigerated: ≤ 10 days
    • Frozen (≤ -25 to -10°C): ≤ 45 days

Why this matters: Wrong category = wrong BUD = unsafe or wasted product. The exam expects you to recognize the environment from the stem (SCA vs cleanroom suite) and assign the correct BUD instantly.

Opened containers and special cases (high-yield for CSPT):

  • Single-dose vials/bags (SDV) after puncture:
    • In ISO 5 or cleaner: up to 12 hours
    • In worse than ISO 5: 1 hour
  • Multi-dose vials (MDV): Up to 28 days after first puncture unless the manufacturer specifies otherwise. Label the puncture date and time.
  • Ampules: Use immediately; do not store after opening. Always use a filter needle or straw to withdraw.
  • Final container integrity: If a container is compromised (leaks, cracks, loose ports), the BUD is moot—the product is unsafe.

Garbing and Hand Hygiene: Exact Order and Testable Details

Improper garbing is the fastest way to fail a media-fill or gloved fingertip test. The sequence prevents shedding and keeps bioburden out of the cleanroom.

Before entering the ante-room or SCA: No food, gum, or drinks. Remove jewelry, watches, earbuds. No makeup or artificial nails. Use low-lint clothing.

Donning sequence (typical for non-hazardous sterile compounding):

  • Shoe covers (or dedicated clean shoes)
  • Head/hood cover and facial hair cover
  • Face mask (and eye protection if needed)
  • Hand hygiene with soap and water for at least 30 seconds; clean under nails; dry with low-lint towel
  • Gown (low-lint; snug at wrists)
  • Enter buffer room (or approach PEC in SCA)
  • Apply alcohol-based hand rub to dry hands
  • Don sterile gloves
  • Sanitize gloved hands with sterile 70% IPA; allow to dry

Why this order works: You cover high-shed areas first (hair, shoes), clean hands before touching the gown, then perform a final alcohol rub and don sterile gloves right before the PEC so gloves stay clean. Frequent glove sanitization (sterile 70% IPA) is required—before each new item, after touching non-sterile surfaces, and every few minutes during compounding.

Working in the PEC: Aseptic Technique That Earns Full Credit

Inside the hood, you protect “first air” and avoid disrupting airflow. Most exam traps center on blocked airflow and poor site disinfection.

  • Set up correctly: Place only necessary items inside. Keep all items at least 6 inches inside the front edge. Avoid clutter; it causes turbulence.
  • Cleaning before use: Disinfect interior surfaces at the start of the shift and before each compounding session with sterile 70% IPA. Use overlapping, unidirectional strokes from clean to dirty:
    • Horizontal LAFW: back-to-front
    • Vertical flow: top-to-bottom
  • First air protection: Keep critical sites (needle, syringe tip, vial stopper, ampule neck) directly in first air. Do not place hands or supplies upstream of those sites. Work in straight lines; avoid sweeping motions.
  • Disinfect stoppers and ports: Use sterile 70% IPA with firm friction for at least 10 seconds and allow to dry completely. Wet alcohol can pull microbes inward.
  • Vials: Use proper pressure equalization. For small volumes, inject air equal to the volume you will withdraw; for large bags or partial packages, adjust to prevent coring or aerosolization. Bevel up, enter at a 45° angle, then turn bevel down in fluid.
  • Ampules: Swab, score if needed, break away from you with gauze or ampule breaker. Use a filter needle to withdraw; switch to a non-filter needle before injecting into a final container.
  • Needle/syringe basics: Keep the cap and tip sterile. Do not touch the plunger shaft. Keep movements slow and deliberate to preserve airflow.
  • Do not spray IPA into the HEPA filter. Never block or wipe the HEPA face.
  • Workflow order: Move from cleanest to dirtiest tasks; start with products that are preservative-free or for sensitive patients (neonates) before multi-dose items.

Cleaning and Disinfecting: What, When, and With What

Cleaning removes soil; disinfecting kills microbes; sporicidal agents address spores. The exam wants frequency and sequence.

  • PEC (hood) interior:
    • At the beginning of each shift
    • Before each batch
    • Every 30 minutes during continuous compounding
    • After spills
    • When contamination is suspected
  • Buffer and ante-room surfaces:
    • Work surfaces: daily
    • Floors: daily
    • Walls, ceilings, storage shelving: regularly (often monthly) and when visibly soiled
    • Use a sporicidal agent at least monthly on appropriate surfaces
  • Agents: Sterile 70% IPA for routine disinfection inside the PEC; EPA-registered disinfectants and sporicidals per facility SOP for rooms. Use low-lint wipes; no cardboard inside the buffer room.

Why it matters: Microbial counts rebound quickly. Frequent PEC disinfection keeps surfaces at or below action levels so aseptic technique has a fair chance to work.

Environmental Monitoring and Competency Tests

Ongoing testing proves your environment and technique are actually safe. Expect several questions on what is tested, how often, and what results trigger action.

  • Certification of PECs and cleanrooms: At least every 6 months and after moves, repairs, or filter changes. Verifies airflow, HEPA integrity, and nonviable particle counts.
  • Pressure differentials: Continuously monitored or checked each compounding day; recorded per SOP. Positive pressure for non-HD buffer relative to ante-room; correct signage if alarms occur.
  • Viable air sampling: At least every 6 months (and after changes). Action levels defined by ISO classification.
  • Surface sampling: At least monthly in PEC, work surfaces, and other high-touch areas. Do this after cleaning but before disinfection to assess effectiveness.
  • Personnel competency:
    • Garbing and hand hygiene competency with observation and documentation
    • Gloved fingertip/thumb sampling (GFT): Initial qualification requires three consecutive passing samples with zero CFU after garbing. Ongoing at least semiannually with very low results expected (facilities often set an action level > 3 CFU). Any failures require retraining and resampling.
    • Media-fill test: Initial and at least semiannual to demonstrate aseptic technique. Incubate per SOP; any turbidity is a failure and requires investigation and retraining.

Why this matters: Clean rooms drift out of control without surveillance. Personal technique also drifts. These tests catch problems before patients do.

Documentation That Protects Patients and Your Score

Good records make errors visible and traceable. The exam expects you to know what must be recorded and labeled.

  • Master formulation record (MFR): “Recipe” with ingredients, quantities, equipment, steps, container/closure, and expected yield.
  • Compounding record (CR): What you actually did: lot numbers, expiration dates, quantities weighed/measured, initials of preparer and checker, calculated final volume/strength, any deviations, and assigned BUD.
  • Labels for CSPs: Patient name (if patient-specific), drug name and strength, total volume, diluent and concentration, route of administration, BUD and time, storage conditions, auxiliary warnings (e.g., “for IV use only,” “protect from light”), and identifying numbers to link to the CR.
  • Quality logs: Cleaning/disinfection logs, temperature logs (fridge/freezer/room), pressure logs, certification reports, competency records.

Why it matters: If a recall happens, lot tracking is your lifeline. If a dose looks wrong, the CR lets a second verifier catch it on paper before it reaches a patient.

Calculations and Compatibility: Common Pitfalls

Even perfect technique can’t fix a wrong dose or an incompatible mixture. Expect straightforward math and logic checks.

  • Concentration conversions: % w/v means g per 100 mL. Example: 2% = 2 g/100 mL = 20 mg/mL.
  • Dose-volume: Volume needed = ordered dose (mg) / concentration (mg/mL). Double-check total additive volume to keep final volume accurate.
  • Dilutions: Use C1V1 = C2V2. Watch units. Convert all concentrations to the same basis before solving.
  • Electrolytes: mEq = (mg × valence) / molecular weight. Know common ones (Na+, K+, Ca2+ in gluconate vs chloride).
  • Osmolarity/tonicity basics: Avoid hypotonic IV solutions unless specifically ordered. Many neonatal routes require strict osmolarity caps (facility policy).
  • Compatibility: Acid-base and calcium-phosphate precipitation are frequent exam themes. Order of mixing for parenteral nutrition matters: add phosphate early, calcium near the end, keep temperature low, and respect solubility curves. When in doubt, flag for pharmacist verification.

Common Exam Traps and How to Avoid Them

  • Trap: “Prepared in SCA; assign BUD 10 days refrigerated.” Wrong. SCA = Category 1. BUD is ≤ 24 hours refrigerated.
  • Trap: “Swab stopper and puncture while still wet.” Wrong. Alcohol must dry to be effective and to avoid wicking microbes inward.
  • Trap: “Use MDV for 35 days if looks clear.” Wrong. Default MDV BUD is 28 days unless the manufacturer says otherwise.
  • Trap: “Open ampule; store remainder in fridge.” Wrong. Ampules are single-use; discard remainder.
  • Trap: “Gloved fingertip pass with 2 CFU is fine for initial qualification.” Wrong. Initial requires three consecutive plates with zero CFU.
  • Trap: “Clean hood once daily.” Incomplete. PEC must be disinfected at start of each shift, before each batch, every 30 minutes during continuous compounding, and after spills.
  • Trap: “Place supplies against the back grill for stability.” Wrong. Never block the HEPA; keep items away from the rear grille.

Quick Checklists You Can Use on Shift

Garbing and entry

  • Remove jewelry/makeup; don shoe, head, facial hair covers; mask
  • Wash hands 30 seconds, dry; don gown
  • Alcohol hand rub; don sterile gloves; sanitize gloves with sterile 70% IPA

PEC setup and technique

  • Disinfect PEC (back-to-front or top-down); allow surfaces to dry
  • Stage only needed items; 6 inches inside front edge
  • Disinfect vial stoppers/ports 10 seconds; let dry
  • Protect first air; slow, steady motions; re-sanitize gloves often
  • Filter needle for ampules; switch needle before injection

Cleaning frequencies

  • PEC: start of shift, before each batch, every 30 min during work, after spills
  • Surfaces/floors: daily; walls/ceilings/shelving: regularly (often monthly)
  • Sporicidal: at least monthly

Core BUD rules

  • Category 1 (SCA): 12 hours room temp; 24 hours fridge
  • Category 2 (cleanroom suite, sterile components): 4 days room; 10 days fridge; 45 days frozen
  • SDV after puncture: 12 hours in ISO 5; 1 hour otherwise
  • MDV: 28 days unless labeled otherwise; ampules: immediate use

Practice Scenarios (Think Like the Exam)

Scenario 1: You are asked to compound cefazolin 2 g in 100 mL NS in an SCA using a horizontal LAFW. The nurse needs it tomorrow morning. What BUD do you assign, and what are the key contamination risks to avoid?

  • Answer approach: SCA → Category 1 → BUD ≤ 12 hours room temp or ≤ 24 hours refrigerated. For “tomorrow morning,” 24 hours refrigerated may still be too short depending on time—confirm timing or re-time the preparation. Risks: failing to let alcohol dry on vial stopper, blocking first air with your hands, insufficient PEC disinfection, not sanitizing gloves frequently.

Scenario 2: A multi-dose vial of insulin was opened in the buffer room five days ago. It’s still clear and labeled with open date. Can you use it today for a TPN in the cleanroom suite?

  • Answer approach: MDV default BUD is 28 days unless the manufacturer states otherwise. Five days is acceptable if stored properly and labeled. Disinfect stopper (10 seconds; let dry). Draw with sterile technique; minimize coring. For PN, verify stability and compatibility in the MFR and resources; add insulin in the correct order and document lot numbers.

Scenario 3: During a semiannual GFT, your plate grows 5 CFU. What now?

  • Answer approach: This exceeds common action levels. You need retraining on hand hygiene/garbing and aseptic technique, investigation of possible causes (damaged gloves, improper garbing sequence, inadequate alcohol drying), and repeat testing until passing. Document actions.

Why These Details Help You Pass

USP <797> isn’t trivia. Each rule has a purpose tied to contamination risk. Memorizing the numbers gets you partway there; understanding the “why” lets you reason through unfamiliar questions. If you can:

  • Identify Category 1 vs Category 2 from the environment described
  • Assign correct BUDs, including SDV/MDV and ampule rules
  • Execute and explain garbing order and aseptic technique choices
  • State cleaning frequencies and monitoring requirements
  • Complete accurate records and labels while doing the math

…you’ll handle both the exam and real cleanroom work with confidence. Practice the motions, not just the words. Slow hands, dry alcohol, clear first air, clean-to-dirty strokes, and precise documentation—those habits are what USP <797> is testing for, and they’re how you keep patients safe.

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