The need for adequate hand protection when handling cytotoxic drugs is paramount. Richard Bryant, group sales director, Nitritex, reviews the issues and benefits of double gloving.
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, protection from the majority of routine pharmaceutical materials was provided through the wearing of a pair of thick latex gloves. However, this type of glove does not give the required protection against the permeation of cytotoxics. While some companies market latex gloves as offering protection against cytotoxics, it is worth checking the product information provided by the manufacturer thoroughly, as they may not meet the most current and stringent requirements.
Before examining 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 (µg/cm²/minute). 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 (EN 374), which limits it to 1.0µg/cm²/minute. While this rate may, at a 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 0.01µg/cm²/minute. This is 100 times more stringent than the old European EN 374-3:1996 standard, AND makes wearer safety the number one priority.
It should be pointed out that the EN 374-3:1996 standard was revised in 2003 and test results obtained under the 1996 standard should no longer be used.
Current practice
Nitritex recently conducted some research into current practices, knowledge levels and general concerns about handling cytotoxics in cytotoxic drug manufacturing plants and hospital pharmacies with isolators or laminar (uni-directional) flow cabinets, in a number of European countries. The results of that research provided the following observations:
• With a few exceptions, double gloving has become the standard operating procedure (SOP).
• There is a universal dislike of 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.
• Environments in which cytotoxic drugs are prepared vary from non-sterile laboratory environments with laminar flow hoods through to sterile aseptic EU GMP Class A cleanrooms with isolators or laminar flow hoods and benches.
• Where double gloving is the SOP, the type of under-glove used varies from a non-sterile powder-free latex exam glove packed in a cardboard box to a sterile non-latex glove in plastic, cleanroom compatible packing.
• Sterile latex surgical gloves, packed in paper wrappers, are used as the outer glove on isolators more frequently than any other type of glove, despite no testing having been 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 double gloving system exists.
• Staff, while generally aware of the need to reduce all possible sources of environmental contamination e.g. paper, have little know-ledge of how this can be achieved in practice.
Latex protein allergy
Most users were 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, a further concern is of latex allergy in patients who are receiving cytotoxic drugs intravenously that have been prepared by operators wearing latex gloves. Those aware of this concern have declared their facilities latex-free zones.
Another possibility is the Type 4 allergy, caused by accelerators used in the production of gloves. Most operators were not aware of the existence of gloves that are totally free of these toxic chemicals.
While 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 non-latex gloves, in particular nitrile, do not have anything close to the elasticity of latex and are therefore stiffer and more uncomfortable than latex. They are also a problem 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, it was evident that there was a real requirement for a dedicated double gloving system to solve all the issues. 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
• 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 tearing, and must slide easily out of the outer glove at the end of the session
• Flexibility – the range of gloves must offer the 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 identified and rectified before permeation of the inner glove can occur
• Accelerator free – the inner glove should be free of accelerators to reduce the possibility of Type 4 allergies
• Latex feel – the glove needs to have the feel of latex while 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
Nitritex has been able to introduce a range of gloves that encompasses all the above requirements. Under the umbrella BioClean brand, a range of outer and inner cleanroom compatible non-latex gloves is now available to meet the demands of safety and efficiency conscious cytotoxic drug manufacturers and pharmacies.
Contact
Nitritex Minton Enterprise Park, Oaks Drive Newmarket, Suffolk CB8 7YY, UK • T +44 1638 663338 • F +44 1638 668890 • sales@nitritex.com • www.nitritex.com
