HEPA Filter
A HEPA (High-Efficiency Particulate Air) filter is an air filtration device that removes at least 99.97% of particles 0.3 microns or larger, used in laminar airflow workbenches and cleanrooms to maintain the sterile environment required for compounding sterile preparations.
Exam Tip
HEPA = 99.97% efficient at 0.3 microns. Certified every 6 months. ISO 5 = inside hood, ISO 7 = buffer room, ISO 8 = ante-area. Critical for sterile compounding under USP 797.
What Is a HEPA Filter?
A HEPA (High-Efficiency Particulate Air) filter is a critical component of sterile compounding environments in pharmacy. It removes airborne particles, bacteria, and fungi from the air supply to create the ultra-clean conditions required by USP 797 for preparing sterile medications.
HEPA Filter Specifications
| Specification | Detail |
|---|---|
| Filtration Efficiency | 99.97% minimum |
| Particle Size | 0.3 microns and larger |
| Standard | DOE standard for HEPA classification |
| Lifespan | Typically 3-5 years (depends on use) |
| Certification | Must be certified every 6 months |
Where HEPA Filters Are Used in Pharmacy
| Equipment | Purpose |
|---|---|
| Laminar Airflow Workbench (LAFW) | Provides ISO 5 air in the direct compounding area |
| Biological Safety Cabinet (BSC) | Protects both product and personnel (hazardous drugs) |
| Compounding Aseptic Isolator (CAI) | Enclosed sterile compounding environment |
| Ceiling HEPA units | Maintains ISO 7 (buffer room) and ISO 8 (ante-area) air quality |
ISO Classifications and HEPA Filtration
| ISO Class | Max Particles (per m3, >=0.5 um) | Pharmacy Area |
|---|---|---|
| ISO 5 | 3,520 | Inside LAFW/BSC (direct compounding area) |
| ISO 7 | 352,000 | Buffer room (cleanroom) |
| ISO 8 | 3,520,000 | Ante-area |
HEPA Filter Maintenance
- Must be certified every 6 months by qualified personnel
- Certification includes DOP (Dioctyl Phthalate) or PAO testing for leaks
- Pre-filters should be changed regularly to extend HEPA filter life
- Damaged HEPA filters must be replaced immediately
Exam Alert
HEPA filters are tested under the Patient Safety and Quality Assurance domain on the PTCE. Know the 99.97% efficiency at 0.3 microns, that certification is required every 6 months, and the ISO classification levels (5, 7, 8) for pharmacy cleanrooms.
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Related Terms
USP 795 and USP 797 (Compounding Standards)
USP 795 and USP 797 are United States Pharmacopeia chapters that establish minimum standards for non-sterile compounding (795) and sterile compounding (797), including personnel training, facilities, equipment, and quality assurance requirements.
Aseptic Technique
Aseptic technique is a set of practices and procedures used in sterile compounding to prevent microbial contamination of compounded sterile preparations (CSPs), including proper gowning, hand hygiene, and manipulation within a laminar airflow hood.
Laminar Airflow Workbench (LAFW)
A Laminar Airflow Workbench (LAFW) is a sterile compounding device that uses HEPA-filtered unidirectional airflow to provide an ISO Class 5 environment for preparing sterile preparations such as IV admixtures and ophthalmic solutions.
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