Background and Importance Investigational drug products (IDP) should be treated as hazardous drugs (HD) as it is not frequent to have hazard studies available or the information about safety is usually insufficient. This is a handicap for pharmacists, who must guarantee the safety of professionals during the handling, preparation and administration of IDP as well as drug quality.

Recommendations by NIOSH and USP include the use of closed system transfer devices (CSTDs) in the healthcare setting to reduce occupational exposure to HD.

Frequently there is a lack of information about the potential impact of using CSTDs on product quality. This may be a challenge, especially when they are used with IDP, monoclonal antibodies (mAb) and drug-conjugated mAb.

Aim and Objectives To review the scientific evidence related to the use of CSTDs when compounding and administering IDPs, in order to determine the main challenges related to its use and to establish the use criteria in daily practice.

Material and Methods A comprehensive search in PubMed database was performed. The search strategy was based on a combination of the following terms: closed system transfer devices, drug development and biologic products (meSH term). We included studies evaluating CSTD, safe handling and drug quality.

Results We included 7 articles (one systematic review, four reviews and two prospective studies) that showed the following critical issues:

• There is a wide variety of components in CSTDs that can potentially cause incompatibility issues, physical and chemical instabilities as well as drug loss and poor quality product due to adsorption onto CSTD materials.

• CSTDs are associated with higher incidence of insoluble fine particles related to silicone oil droplets. MAb are known to form aggregates when CSTDs are used that could be potentially detrimental to patient safety.

• CSTDs holdup volume range from 0,04 to 1 mL which has an impact on deliverable drug dose which is especially worrying in low volume-dose IDP.

Conclusion and Relevance Frequently, there is insufficient information to exclude safety concerns for IDP leading to broad use of CSTDs according to guidelines.

There is an urgent need to increase knowledge about the hazard of new therapies and to assess CSTDs impact on product quality, clinical trial outcome and patient safety.

Conflict of Interest No conflict of interest.