Sterile Preparations - NAPLEX

1. What does ISO Class 5 mean for airborne particle limits in the primary engineering control?

   An environment meeting ISO 14644-1 Class 5 particle limits at rest/operational. ISO Class 5 limits airborne particles to ≤3520 per cubic meter (≥0.5 μm) to maintain an aseptic environment for sterile compounding.

2. What is the osmolarity formula using millimoles and dissociation factor?

   $\text{mOsmol/L}=\text{mmol/L}\times i$. Osmolarity accounts for particle dissociation, predicting solution tonicity for safe parenteral administration.

3. Which direction does air flow in a vertical laminar airflow workbench or biological safety cabinet?

   From the HEPA filter at the top downward toward the work surface. Vertical flow pushes contaminants downward, ensuring the work surface receives clean air directly from the overhead HEPA filter.

4. What is the correct order for donning garb for sterile compounding before entering the buffer area?

   Shoe covers, head/facial hair cover, mask, hand hygiene, gown, sterile gloves. This sequence minimizes contamination by covering potential microbial sources before hand hygiene and final sterile barriers.

5. What is the formula for percent volume/volume concentration ($\%\ \text{v}/\text{v}$)?

   $\%\ \text{v}/\text{v}=\frac{\text{mL solute}}{\text{mL solution}}\times 100$. This formula measures the volume of liquid solute in the total solution volume, used for concentrations of miscible liquids.

6. Calculate volume needed: Stock is $50\ \text{mg/mL}$; dose is $125\ \text{mg}$; what mL is required?

   $2.5\ \text{mL}$. Dividing dose by stock concentration determines the precise volume required for administration.

7. Which PEC is appropriate for compounding hazardous sterile preparations requiring containment?

   A Class II biological safety cabinet (BSC) or a compounding aseptic containment isolator. These PECs provide containment for hazardous drugs, ensuring personnel and environmental protection alongside product sterility.

8. What is the correct way to disinfect vial stoppers and ampule necks before access?

   Scrub with sterile $70\%$ IPA and allow to dry before puncture/breaking. Scrubbing removes surface contaminants, and drying ensures no residual moisture that could dilute or compromise sterility.

9. What is the standard hand hygiene method immediately before donning sterile gloves?

   Hand and forearm wash, then dry with lint-free towel before gloving. Thorough washing removes dirt and microbes, followed by drying to prevent lint contamination before applying sterile gloves.

10. What is the major difference between a LAFW and a biological safety cabinet (BSC)?

    BSC provides personnel/environment protection; LAFW protects product only. BSCs contain hazardous materials to protect the operator and surroundings, while LAFWs focus solely on product sterility without containment.

11. What is the definition of a sterile preparation (sterile compounded preparation)?

    A preparation compounded in an aseptic environment to be free of viable microbes. Sterile preparations are compounded under controlled aseptic conditions to eliminate viable microorganisms and prevent patient infections.

12. What is the purpose of a filter needle when preparing doses from an ampule?

    To remove particulate matter (glass) during withdrawal from the ampule. Filter needles trap glass fragments generated during ampule opening, ensuring the injectable solution remains free of particulates.

13. What is a critical site in sterile compounding?

    A component location that must remain sterile (e.g., needle, syringe tip, septum). Critical sites are vulnerable points where microbial entry could compromise the entire preparation's sterility.

14. What is the primary purpose of a laminar airflow workbench (LAFW) in sterile compounding?

    To provide ISO Class 5 unidirectional HEPA-filtered air over the work area. LAFW maintains an ISO Class 5 environment by directing HEPA-filtered air unidirectionally to minimize airborne contamination during compounding.

15. What agent is used to disinfect sterile gloves during compounding in the PEC?

    Sterile $70\%$ isopropyl alcohol (IPA). Sterile 70% IPA effectively kills microbes on gloves without leaving residues, maintaining asepsis during the compounding process.

16. What is the formula for milliequivalents when valence is known?

    $\text{mEq}=\frac{\text{mg}\times \text{valence}}{\text{molecular weight}}$. This equation converts mass to equivalents based on ionic charge, essential for electrolyte balance in IV preparations.

17. Identify the correct needle filter size used to remove glass particles when withdrawing from an ampule.

    A $5\ \mu\text{m}$ filter needle or filter straw. A 5 μm filter captures glass shards ≥5 μm, preventing particulate contamination in the final preparation.

18. Which statement best defines first air in aseptic technique?

    The unobstructed HEPA-filtered airflow directly exiting the filter face. First air provides the cleanest, most direct HEPA-filtered airflow to critical sites, minimizing contamination risk.

19. Which direction does air flow in a horizontal laminar airflow workbench?

    From the HEPA filter at the back toward the operator (horizontal flow). Horizontal flow sweeps contaminants away from the critical work area by directing clean air from the rear HEPA filter toward the front.

20. What is the correct placement of supplies inside a PEC to avoid blocking first air to critical sites?

    Keep critical sites in first air; place items to the side and not upstream. Side placement prevents airflow obstruction, ensuring critical sites receive uninterrupted first air for aseptic protection.

21. Calculate a dilution: You need $10\ \text{mL}$ of $2\ \text{mg/mL}$ from $10\ \text{mg/mL}$; what stock mL?

    $2\ \text{mL}$. Using the dilution formula $C_1V_1 = C_2V_2$ calculates stock volume needed to achieve the desired final concentration.

22. What is the formula for percent weight/volume concentration ($\%\ \text{w}/\text{v}$)?

    $\%\ \text{w}/\text{v}=\frac{\text{g solute}}{\text{mL solution}}\times 100$. This formula quantifies solute mass per unit volume of solution, expressing concentration as a percentage for pharmaceutical calculations.

23. What is the correct technique to prevent coring when puncturing a vial stopper?

    Insert needle bevel up at about a $45^\circ$ angle, then straighten to $90^\circ$. This angle minimizes rubber coring by piercing rather than cutting, preserving vial integrity and preventing particulate contamination.

24. Calculate the final concentration: Add $500\ \text{mg}$ drug to $250\ \text{mL}$; what is $\text{mg/mL}$?

    $2\ \text{mg/mL}$. Dividing total mass by volume yields concentration, ensuring accurate dosing in compounded preparations.

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