routines are deployed. This issue has been
demonstrated in the ‘real-life’ setting 4 where
cytotoxic contamination was not only found on
wipe samples from the inside of the isolator, but
also on the external surfaces of pre-filled syringes
and infusion bags passed out of the isolator and
into the aseptic room. When these are then taken
to clinical areas for administration to patients,
the cytotoxic contamination is transferred with
them, potentially contaminating clinic and
patient areas and exposing nursing staff, non-
cancer patients and patient carers to risk. It
would therefore be erroneous to think of isolators
as a ‘single and final solution’ for reducing cytotoxic
contamination in the pharmacy and the clinic.
CSTDs are designed to contain cytotoxic
residues and aerosols within the device itself.
There has been debate over which CSTDs on the
market are ‘genuine’ closed systems.
Manufacturers of devices with air-displacement
chamber technology argue that devices where
displaced air is exhausted through hydrophobic
filters and activated charcoal are not closed
systems amid concern that not all cytotoxic
molecules are trapped by the filter system and
that repeated use may saturate the filter.
Reference to studies published on these devices
tends to show that they all reduce contamination
on workplace surfaces when tested in the field
using cytotoxic drugs, irrespective of the CSTD
design, albeit with some variation in
effectiveness. 5,6 In one study, 4 the CSTD
significantly reduced cytotoxic contamination on
the external surfaces of pre-filled syringes and
infusion bags leaving the isolator when compared
with standard needle and venting pin techniques.
Even with these encouraging findings, CSTDs
should not be considered a ‘panacea’ for
eliminating cytotoxic contamination and some
devices exhibit residual droplets of liquid on
docking valves after disconnection. Also,
contamination may arise from multiple sources
and some of these are not mitigated by the use of
CSTD technology, for example contamination on
the outside of drug vials. The cost of
implementing CSTDs may also prove challenging.
There seems to be a developing argument for
combining the use of CSTDs and isolators, with
the intention of reducing cytotoxic contamination
inside the isolator and minimising the transfer of
cytotoxic residues to the outer surface of syringes
and infusion bags leaving the isolator. The key
question then would be whether this measure,
when combined with the use of closed-system
infusion administration sets, can reduce cytotoxic
contamination in clinical areas and reduce the
occupational exposure risk to nursing and clinic
staff. There is a clear need for research in both
pharmacy and clinical areas to evaluate this
approach. The paucity of evidence on the
effectiveness of CSTDs was highlighted in a
Cochrane Review 7 commissioned by the UK
Oncology Nursing Society. Some experts in the
field consider this review to be poorly conducted
and unhelpful, 8,9 but it does serve to highlight the
need for well-designed studies to evaluate new
technologies or combinations of technologies.
The current interest in robotic chemotherapy
compounding systems may present another
opportunity for combining isolator/Class II
cabinet and CSTD technology. With the cleaning
and decontamination issues presented by
complex robotic systems, this combination
offers the potential for environment and
product protection together with reduced
cross-contamination between batches of different
products.
Regulatory controls and microbiological
considerations restrict the re-use of part-used
vials of chemotherapy drugs. This results in
considerable drug wastage which is unacceptable
in the challenging economic conditions of
modern cancer care. The use of CSTDs has been
proposed as a potential option to effectively
replace a multiple needle-entry vial septum with
a syringe docking device to maintain vial integrity
and permit multiple or extended use. 10 However,
as discussed above, there is still the integrity of
the seal between the CSTD spike or needle and
the vial septum over prolonged time-periods to
consider. Use of CSTDs in this context would need
extensive microbiological validation and also an
assessment of materials leaching from the device
fluid path when in prolonged contact with
cytotoxic drug infusions, some of which are
formulated with aggressive co-solvent systems
which could attack plastic and metal components
of the device.
Conclusions
It seems likely that optimal cytotoxic
containment and maintenance of infusion
sterility requires a combination of current
technologies. The implementation of CSTDs in
pharmaceutical compounding units when used in
combination with isolators, and their use in
clinics for chemotherapy administration, may be
the way forward. This would require a joined-up
approach by pharmacy and nursing staff, and
careful evaluation in terms of cost and benefit.
17
HHE 2019 | hospitalhealthcare.com
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Note
As an opinion piece, this article
is not extensively referenced.
If additional reference sources
are required, please contact the
author.