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Published on 2 March 2009

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Double gloving when handling cytotoxic drugs

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The need for adequate hand protection for staff handling cytotoxic drugs is paramount. Of particular importance is a suitable double-gloving system

Harry Kirk
Business Development
Director
Nitritex

Whether it is working on a bench under a laminar flow hood or in an isolator cabinet, it is vital that staff should be protected from exposure to damaging cytotoxic drugs. In the past, a certain level of protection was provided by wearing a pair of thick latex gloves. Whilst this gave the appearance of offering a
high level of protection against permeation by cytotoxics, the reality has proven to be very different, as evidenced by independent test results.

Before we examine permeation in detail, we need to define what it means. Permeation is the transfer of a chemical through a glove at a molecular level and is measured in micrograms per square centimetre per minute (¼g/cm – ²/min). This flow is not visible and the inability to see the drug in contact with the skin makes it all the more important that the glove in use has a
proven resistance to permeation.

Historically, in Europe, permeation has been measured in accordance with an industrial glove standard (EN374) which limits it to 1.0 ¼g/cm2/min.

Whilst this rate may, at first glance, appear to be sufficiently stringent, the new American Standard, ASTM D 6978-05, which has been formulated specifically for cytotoxic drugs, sets a maximum acceptable limit of permeation at 0.01 ¼g/cm2/min. This is 100 times more stringent than the old European
EN374-3:1996 standard, making wearer safety the number one priority.

It should be pointed out that the EN374-3:1996
standard was revised in 2003 and test results obtained under the 1996 standard should no longer be used.

Research of current practices, knowledge levels and general concerns
Our research, conducted in a number of European countries in cytotoxic drug manufacturing plants and hospital pharmacies with isolators and/or laminar (unidirectional) flow cabinets, yielded the following observations:

  • With a few exceptions, double gloving has become the standard operating procedure (SOP).
  • There is a universal dislike for thick latex gloves, which substantially reduce dexterity and efficiency.
  • Although the outer glove worn during the preparation of the drugs is invariably sterile, the inner glove is not always sterile.
  • The use of sterile alcohol is widespread in ensuring that surfaces, including gloves, are sanitised.
  • Environments in which cytotoxic drugs are prepared vary from nonsterile laboratoryenvironments with laminar flow hoods through to sterile aseptic EU GMP Class A cleanrooms with isolators and/or laminar flow hoods and benches.
  • Where double gloving is the SOP, the type of under-glove used varies from a nonsterile powderfree latex exam glove packed in a cardboard box to a sterile nonlatex glove in plastic, cleanroom compatible packing.
  • Sterile latex surgical gloves, packed in paper wrappers, are used as the outer glove on the isolators more frequently than any other type of glove, despite there being no testing carried out to confirm their suitability for the task.
  • Many staff are unaware of the need to wear gloves that have been extensively tested for their resistance to permeation by cytotoxic drugs.
  • Very few staff know that a dedicated doublegloving system exists.
  • Many gloves have small holes close to the cuff. Whilst these are allowed under EN455, where the glove is seated over the isolator cuffs, the continuous stress causes the cuff to split.
  • Staff, whilst generally aware of the need to reduce all possible sources of environmental contamination (eg, paper) have very little knowledge of how this can be achieved in practice.
  • Most users are not fully aware of the very small, but existing potential of a glove wearer acquiring a type 1 latex protein allergy. In this era of litigation, latex allergy in patients who are receiving cytotoxic drugs intravenously is also a concern where these drugs are prepared by operators wearing latex gloves. For those that are aware of this concern, their facilities have been declared latex-free zones.
  • Another possibility is type 4 allergy, caused by accelerators used in the production of gloves. Most operators are not aware of the existence of gloves that are totally free of these toxic chemicals.
  • Whilst our research showed that there was some desire to get away from latex due to the risk of type 1 latex protein allergy, latex has always been the material of choice for gloves due to its great elasticity. Most nonlatex gloves, in particular nitrile, do not have anything close to the elasticity of latex and are therefore stiffer and more uncomfortable than latex, and are also difficult to install on the isolator cuffs.

Developing a solution
Bearing in mind the research detailed above, which was carried out over a two-year period in a number of European countries, it was evident that there was a real requirement for a dedicated double-gloving system that provided the solution to all of the issues raised. Any such system had to demonstrate the
following attributes:

  • No latex – this would remove the source of latex proteins and hence the potential for developing a type 1 latex protein allergy. This would have to apply to both the inner and outer gloves.
  • Integrity – the outer glove must not fail (tear or perforate) when installed on the isolator cuff or when being donned over the inner glove.
  • Protection – both inner and outer gloves must demonstrate a permeation resistance superior to latex gloves and provide glove wearers with confidence in the protection afforded.
  • Donning – the inner glove must slide easily inside the outer glove without causing any tearing of the outer glove, and must slide easily out of the outer glove at the end of the session.
  • Flexibility – the range of gloves must offer the glove wearer options in the level of tactility and protection sufficient to suit all environments and SOPs.
  • Contamination control – gloves need to be processed and packed to minimise the risk of contaminating the cytotoxic drugs. Paper packing of any sort is definitely a major contamination risk and must be eliminated.
  • Glove failure – if a failure in the outer glove occurs it must be easily identifiable and so that it can be rectified before permeation of the inner glove can occur.
  • The inner glove should be free of accelerators to reduce the possibility of type 4 allergies.
  • Latex feel – the glove need to have the feel of latex whilst being free of latex proteins.
  • Sensitivity – the thickness of the combined double-gloving system needs to be less than the thickness of the latex glove from the current market leader.

Only one glove manufacturer has been able to introduce a range of gloves that match all the above criteria. Nitritex, the global manufacturer and supplier of cleanroom gloves, now manufactures a double-gloving system that encompasses all of the above requirements.

Under the umbrella BioClean brand, a range of outer and inner cleanroom compatible nonlatex gloves is now available to meet the demands of safety- and efficiency-conscious cytotoxic drug manufacturers and pharmacies. For more information please contact Nitritex via their website: www.nitritex.com.



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