4.2 Sterile Preparations & Hazardous Drug Handling (NAPRA / NIOSH Principles)

4.2 Sterile Preparations & Hazardous Drug Handling (NAPRA / NIOSH Principles)

Sterile compounding involves the preparation of therapeutic formulations free from microbial, particulate, pyrogenic, and chemical contamination. In Canada, sterile compounding is governed by the NAPRA Model Standards for Pharmacy Compounding of Sterile Preparations and the NAPRA Model Standards for Pharmacy Compounding of Hazardous Drugs. These regulatory benchmarks establish stringent requirements for facility architecture, air handling systems, aseptic personnel technique, personal protective equipment (PPE), and continuous environmental quality control.

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Cleanroom Architecture & ISO Air Classifications

Cleanrooms control the concentration of airborne particulate matter to prevent contamination of sterile products. The International Organization for Standardization (ISO) classifies air cleanliness based on the maximum number of airborne particles $\ge 0.5\ \mu\text{m}$ per cubic metre of air:

Unclassified Area ---> ISO Class 8 Anteroom ---> ISO Class 7 Buffer Room ---> ISO Class 5 PEC (DCA)
[Dirtiest / Non-Sterile]                                                  [Cleanest / Critical Area]

Primary Engineering Controls (PECs) vs. Secondary Engineering Controls (SECs)

• Primary Engineering Control (PEC): A certified device or room that provides an ISO Class 5 environment for compounding sterile preparations. PECs rely on High-Efficiency Particulate Air (HEPA) filters, which remove at least $99.97\%$ of airborne particles with a size of $0.3\ \mu\text{m}$ or larger.
• Secondary Engineering Control (SEC): The structural cleanroom suite housing the PEC, consisting of the buffer area (ISO Class 7) and the anteroom (ISO Class 7 or 8). The SEC provides controlled temperature (NAPRA: clean room and anteroom at or below $20^\circ\text{C}$ for personnel comfort in garb) and differential air pressure. NAPRA sets no relative humidity requirement.

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Pressure Differentials: Non-Hazardous vs. Hazardous Cleanrooms

Air pressure differentials prevent the transfer of airborne contaminants between adjacent cleanroom suites. The direction of air movement is dictated by whether the drugs being manipulated pose toxicity risks to personnel:

NON-HAZARDOUS STERILE FACILITY (Positive Pressure Regime):
  [General Pharmacy]  <---  [ISO Class 8 Anteroom]  <---  [ISO Class 7 Buffer Room (PEC)]
      (Ambient)            (+5.0 to +12.5 Pa vs pharmacy)   (+5.0 to +12.5 Pa vs anteroom)
  *Air flows OUTWARD from cleanest area, preventing dust/microbes from entering.

HAZARDOUS STERILE FACILITY (Negative Pressure Regime):
  [General Pharmacy]  <---  [ISO Class 7 Anteroom]  --->  [ISO Class 7 Buffer Room (C-PEC)]
      (Ambient)              (at least +5.0 Pa vs pharmacy)    (at least -2.5 Pa vs anteroom)
  *Air flows INWARD into the hazardous buffer room, preventing cytotoxic vapors from escaping.

1. Non-Hazardous Sterile Cleanrooms (Positive Pressure)

• Pressure Gradient: The clean (buffer) room must maintain positive differential pressure of at least $5.0\text{ Pa}$ (ideally $5.0$ to $12.5\text{ Pa}$, about $0.02$ to $0.05$ inch water column) relative to the anteroom, and the ISO Class 8 anteroom must be positive by the same margin relative to the pharmacy.
• Air Changes: At least 30 ACPH in the clean room and at least 20 ACPH in the anteroom.
• Objective: If a door opens, clean, HEPA-filtered air rushes outward, preventing lower-quality ambient air, dust, and microorganisms from entering the cleanroom.

2. Hazardous Sterile Cleanrooms (Negative Pressure)

• Pressure Gradient: The hazardous clean room (containment secondary engineering control, C-SEC) must maintain negative pressure of at least $-2.5\text{ Pa}$ (about $-0.01$ inch water column) relative to the adjacent anteroom.
• Objective: Prevents carcinogenic, teratogenic, and cytotoxic vapors, dusts, and aerosols from leaking into staff areas or the wider hospital.
• Air Handling Requirements: The clean room and the anteroom must each provide at least 30 air changes per hour (ACPH), and the clean room must be 100% externally vented through dedicated roof exhaust ducting. Air exhausted from hazardous compounding can never be recirculated into general HVAC systems.
• Anteroom Configuration: The anteroom leading into a hazardous clean room must maintain an ISO Class 7 rating (not ISO Class 8) and must be at least $+5.0\text{ Pa}$ relative to the pharmacy, so the anteroom acts as an air barrier between the clean room and the rest of the pharmacy.

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Primary Engineering Controls (PECs) Compared

Different clinical preparations require specific PEC configurations to safeguard product sterility and personnel safety:

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NIOSH Hazardous Drug Lists & Closed System Transfer Devices (CSTDs)

The National Institute for Occupational Safety and Health (NIOSH) maintains the authoritative list of antineoplastic and other hazardous drugs in healthcare settings, categorized into three distinct groups:

• Group 1: Antineoplastic Drugs: Cytotoxic chemotherapeutic agents that pose carcinogenic, mutagenic, or teratogenic risks (e.g., cisplatin, cyclophosphamide, doxorubicin, fluorouracil, methotrexate, paclitaxel, vincristine).
• Group 2: Non-Antineoplastic Hazardous Drugs: Agents that meet one or more NIOSH toxicity criteria (e.g., organ toxicity at low doses, genotoxicity, carcinogenicity) but are not used primarily for cancer therapy (e.g., azathioprine, cyclosporine, tacrolimus, carbamazepine, spironolactone, ganciclovir, zidovudine).
• Group 3: Non-Antineoplastic Drugs with Reproductive / Developmental Effects: Agents that impair fertility or cause fetal harm during pregnancy/lactation (e.g., finasteride, dutasteride, letrozole, misoprostol, mifepristone, ribavirin, thalidomide, warfarin).

Closed System Drug-Transfer Devices (CSTDs)

A Closed System Drug-Transfer Device (CSTD) is a drug-transfer device that mechanically prohibits the transfer of environmental contaminants into the system and the escape of hazardous drug or vapor concentrations outside the system. CSTDs employ physical double-membrane puncture seals or internal equalization chambers with toxic vapor filters.

• Where the requirement comes from: USP <800> in the United States requires CSTDs for administering antineoplastic hazardous drugs when the dosage form allows. NAPRA's hazardous sterile standard does not impose a general CSTD mandate; many Canadian oncology programs adopt CSTDs through provincial or institutional policy. A CSTD is a supplementary control used inside a certified BSC or CACI. It never replaces the ISO Class 5 C-PEC.

NAPRA Beyond-Use Dates for Sterile Preparations

When no stability or sterility data support a longer period, NAPRA's non-hazardous sterile standard sets maximum beyond-use dates by contamination risk level and storage condition:

Preparations made in a segregated ISO Class 5 LAFW outside a clean room carry a beyond-use time of 12 hours or less. A preparation made for immediate use in an emergency must begin administration within 1 hour of the start of preparation.

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Personal Protective Equipment (PPE) & Garbing Protocol

Personnel represent the single greatest source of particulate and microbial contamination in cleanroom environments. Personnel shed thousands of skin squames, respiratory droplets, and microbes per minute. Therefore, garbing must follow a strict sequential progression from dirtiest to cleanest anatomical locations prior to entering the buffer room.

                                  GARBING PROGRESSION (OUTSIDE-IN) 

    [STEP 1: ANTEROOM - DIRTY SIDE]
    1. Remove all jewelry, watches, rings, cosmetics, and outer jackets.
    2. Don dedicated cleanroom shoe covers (one foot at a time, crossing the line of demarcation).
    3. Don head and facial hair covers (ensuring all hair and ears are fully enclosed).
    4. Don surgical face mask and protective eye shield / safety goggles.

    [STEP 2: ANTEROOM - CLEAN SIDE / SINK]
    5. Perform aseptic hand hygiene: Wash hands and forearms up to the elbows with warm water
       and antimicrobial soap for at least 30 seconds. Clean underneath fingernails with a disposable
       nail pick. Dry completely with disposable, lint-free towels.
    6. Don a non-shedding, lint-free disposable gown with snug knit cuffs and a high neck closure.

    [STEP 3: BUFFER ROOM / DIRECT COMPOUNDING AREA]
    7. Enter the ISO Class 7 buffer room.
    8. Disinfect hands with alcohol-based hand rub containing 70% sterile isopropanol (IPA); allow to dry.
    9. Don sterile, powder-free gloves over the gown cuffs.
   10. For hazardous drugs: Don TWO pairs of ASTM D6978 chemotherapy gloves (inner pair under cuff,
       outer pair over cuff). Routinely disinfect outer gloves with sterile 70% IPA.

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Cleanroom Maintenance: Deactivation, Decontamination, Cleaning & Disinfection

Cleaning and sanitizing hazardous drug compounding areas requires four distinct, non-interchangeable chemical actions performed in a precise sequential order:

1. Deactivation: Renders the chemical compound inert or non-toxic through chemical oxidation or destruction. Typical agents include sodium hypochlorite (safety data sheets often recommend a 2% solution; because it corrodes stainless steel, a neutralizer such as sodium thiosulfate or a detergent rinse follows) or accelerated hydrogen peroxide. Quaternary ammonium compounds and alcohol cannot deactivate hazardous drugs.
2. Decontamination: Neutralizes, inactivates, or physically lifts and removes hazardous chemical residues from surfaces. Typical agents include sterile water, surfactants, or alcohol solutions.
3. Cleaning: Physically removes organic and inorganic soil, dirt, and microbial biofilms using a germicidal detergent solution.
4. Disinfection: Destroys viable vegetative microorganisms and fungi on inanimate surfaces using sterile $70\%$ isopropanol (IPA). The sterile IPA must remain wet on the surface for its specified contact time (typically 30 seconds to 1 minute) and allowed to air dry.

Deactivation (Bleach/Peroxide) ---> Decontamination (Surfactant) ---> Cleaning (Detergent) ---> Disinfection (Sterile 70% IPA)

Hazardous Spill Management Protocol

When a hazardous drug spill occurs in the pharmacy:

1. Alert and Evacuate: Immediately warn everyone in the immediate area. Evacuate non-essential personnel and post warning signs.
2. Obtain Spill Kit: Retrieve the dedicated hazardous drug spill kit and don specialized PPE: NIOSH-certified N95 or Powered Air-Purifying Respirator (PAPR), chemical splash goggles, double chemotherapy gloves, and heavy-duty poly-coated chemotherapy gown.
3. Contain the Spill: Cover liquid spills gently with absorbent spill pads to prevent spreading. For powder spills, place damp absorbent towels over the powder to prevent aerosolization.
4. Clean and Deactivate: Work from the periphery of the spill toward the center. Decontaminate the surface using oxidizing deactivating solution, followed by detergent and sterile water.
5. Waste Disposal: Dispose of all contaminated glass, pads, and PPE into yellow, puncture-resistant cytotoxic biohazard waste containers marked for high-temperature incineration.
6. Document: File a formal incident report detailing the drug, estimated volume, cause, and any personnel exposure.