Pharmacy OneSource Blog

Are You Assessing Your Sterile Compounding Risk Accurately?

A number of factors must be weighed when determining the risk level of a compounded sterile product (CSP), including the complexity and number of manipulations involved and the sterility of the base materials and products. Proper assessment of risk level is necessary to determine its beyond use date (BUD), storage requirements, and the sterility testing required on the final product.

How do you know whether you are assessing your sterile compounding risk accurately? Julie Strickland, PharmD provides these guidelines for the four classes of risk.1

Immediate use: CSPs in this category must be used within an hour, and should be used immediately, if possible. They include CSPs used in emergent situations such as for  cardiopulmonary resuscitation or in an operating room or ICU. Outside the hospital, they may involve short-stability medications used for in-home infusions, at an accident site, or in an ambulance.

CSPs for immediate use should be labeled with the patient and preparer names, ingredients, and exact one-hour BUD and time. While these CSPs are not compounded in sterile environments, care should be taken to avoid contamination by observing hand hygiene recommendations and following aseptic technique. Immediate use CSPs should be properly discarded if not used within one hour, according to the ASHP Guidelines on Compounding Sterile Preparations. 2

Low-risk: When compounding involves simple admixtures prepared using closed system transfer methods in an ISO Class 5 laminar airflow workbench (LAFW) environment, biological safety cabinet, or specialized isolator, they are considered low-risk. These CSPs start with sterile commercial ingredients and combine no more than three into the final product. The process involves simple, aseptic transfers from disinfected vials, ampules or bags using sterile needles.

According to the ASHP guidelines, the ISO Class 5 environment used for low-risk CSPs usually must be located within an ISO Class 7 buffer area with an ISO Class 8 ante area, except when preparing low-risk CSPs that will be used within 12 hours. In that case, sterile compounding may occur in a segregated area that lacks an ISO 7 buffer area, but the primary engineering control (PEC) must be located away from potential sources of contamination such as water supplies and drains as well as unsealed windows or doors adjoining high traffic areas, food preparation areas and construction sites.

Medium-risk: These CSPs involve compounding more than three sterile products or use more complex processes such as those required for total parenteral nutrition. The CSP is considered medium-risk if it is prepared in batches for administration to more than one patient or to the same patient over several days. Compounding of these CSPs occurs in an ISO Class 5 environment. Strickland notes that medium-risk compounding includes filling reservoirs of injection and infusion devices with sterile drug products for chemotherapy or pain management and preparing batches of syringes.

High-risk: Using non-sterile ingredients, non-sterile devices or open system transfers is considered high-risk compounding, as well as using sterile ingredients, devices or mixtures that are exposed to conditions worse than ISO Class 5 air for more than one hour. The ASHP guidelines note that using bulk ingredients whose chemical purity and content strength are unknown or undocumented will make a CSP high-risk, as will  compounding by improperly gowned or gloved personnel. High-risk CSPs are compounded in an ISO Class 5 environment.

How do you ensure you have accurately assessed the risk level of your CSPs?


  1. Strickland J. Sterile Compounding Medication Errors of Contamination: When Tragedy Drives Change. FreeCE. December 3, 2014.

  2. ASHP Guidelines on Compounding Sterile Preparations. Drug Distribution and Control: Preparation and Handling–Guidelines. ASHP. Accessed October 6, 2015.

Sterile compounding. Download the guide.

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