Sterile Compounding Equipment, Facilities, and Environmental Monitoring
Primary Engineering Controls and the Buffer Area
A candidate must know the layered design of a sterile compounding space: the primary engineering control (PEC) - laminar airflow workbench, biological safety cabinet, or compounding isolator - sits inside a buffer area (cleanroom), which is separated from the ante area and general pharmacy. ISO classifications matter: a PEC provides ISO Class 5 air at the critical site, while the surrounding buffer area must meet the class appropriate to the compounding risk level. Know the difference between unidirectional (laminar) flow and turbulent flow, and why first-air concepts keep critical sites downstream of the filter.
Monitoring
Understand viable and nonviable environmental sampling: volumetric air sampling, surface sampling, and glove fingertip sampling, plus their frequency and the meaning of excursion and action levels. Certification of PECs and rooms is periodic and performed after moves or major service. Pressure differentials, air changes per hour, and temperature/humidity logs are routine expectations.
Traps
Questions love to confuse the PEC with the buffer area, or ask which particle count applies where. Watch for items that say 'clean the workbench with a disinfectant and immediately begin' - proper practice includes appropriate dwell/wet contact time and allowed residue. Another trap: assuming a hood protects the product from the operator when the real purpose is operator protection (hazardous drugs) versus product protection.
Rule of Thumb
If a question asks where the 'critical site' air quality is defined, the answer is the PEC at ISO Class 5, and airflow must not be blocked between the filter and the critical site.