Closed-System Transfer Devices: Important Considerations for Pharmacists


Closed-system transfer devices (CSTDs) mechanically prohibit the transfer of environmental contaminants into a system and the escape of hazardous drugs or vapor concentrations outside the system. Although the first CSTD was approved in the United States in 1998, several products are currently available, including those with widely varying design characteristics.1-3

Because of these design differences, CSTDs are not a monolithic category of products. One of the most important differences is the method of preventing release of hazardous drugs from each device. Although some devices rely on a carbon filter to limit the escape of hazardous drug vapors, others are mechanically closed. Still, other differences in products may affect real-world use, including the nature of connections. Some devices rely on a needle-free connector, whereas others rely on a needle-based connector between a drug and vials or intravenous bags.2-5 

Pursuant to legally binding regulations for the handling of hazardous drugs published by the United States Pharmacopeia (USP)—a regulation known as USP <800>—several practices that are commonplace in pharmacies throughout the United States will change with respect to the handling of hazardous drugs. For example, USP <800> requires that pharmacies segregate hazardous drugs and other medications through processes of transport, storage, preparation, and delivery to the patient.4-7

With the eventual implementation of USP <800>, all hospitals and health care systems that handle hazardous drugs will eventually have access to CSTDs. USP <800> also recommends but does not require that pharmacies have access to these systems.4-7

Pharmacists must be aware of the differences between available CSTDs, including differences that relate to design characteristics of these products. The important differences between design characteristics of CSTDs may have clinically relevant effects. However, it is difficult to find information about the effects of CSTDs in the design because these products do not have package inserts. Rather, documentation on CSTDs from the FDA is limited to 510(k) submissions, which provide very limited information.8,9

To help address the gap in knowledge with performance of CSTDs, the National Institute of Occupational Safety and Health (NIOSH) is developing a universal protocol that relies on the tile tracer compound 2-phenoxyethanol. This tracer compound may be more amenable for use with filter-based systems but may not be fully representative of the performance of these systems. Makers of mechanically closed systems have consistently opposed the new “universal” protocol.10,11

A NIOSH draft protocol was tested by Massoomi et al at Ohio Nebraska Methodist Hospital. Researchers tested several CSTDs within an isolated system connected to a real-time testing system continuously sampling for the presence of isopropyl alcohol. In these tests, major leaks were detected in all but 2 systems—both mechanically closed—during procedures stimulating drug transfer for preparation of intravenous medications. None of the filter-based systems have passed the NIOSH draft protocol, and the protocol even mentioned that it could only be used with mechanically closed systems. Notably, NIOSH ultimately abandoned the draft protocol using isopropyl alcohol, as according to NIOSH performance of this tracer is, “not representative of the behavior expected with the current population of known hazardous drugs, due to their much lower vapor pressures.”10

Importantly, filter-based systems have not consistently performed well under real-world conditions, and as a result have been banned for sale as CSTDs in some European countries but are marketed in the United States as such.10,11

Understanding that CSTDs are not a monolithic category of products is important for pharmacists, who may be involved in purchasing decisions for these medications, both for their departments and for nursing departments.

By using the best available data to choose a device based on performance, it is important that pharmacists consider results of tests using the draft NIOSH protocol for comparative testing of CSTDs. Although acceptance of the NIOSH protocol was defeated, pharmacists and other health care professionals should evaluate all available information to make decisions to protect the health of those who prepare, handle, and administer hazardous drugs every day.


Michael R. Page, PharmD, RPh, has worked as a community pharmacist at CVS Pharmacy and is currently clinical team lead of clinical communications at Pharmacy Times®.

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Hannah Schroeder
Hannah Schroeder

You mentioned that CSTDs keep environmental contaminants and hazardous drugs from leaving a system. I’d imagine that if the pollutants did escape, it might contaminate other drugs or patients. It sounds like hospitals and medical offices should get them from a CSTD pharmacy.