Exposure
temperature. “Our purpose was to simulate the real-life situation, where gloves are subject to friction, rubbing and stretching – so we designed a system for dynamic measurement of permeability”, Professor Wallemacq says. He and his team designed a device that could provide standardised dynamic conditions for permeability testing.
Whereas previous test methods had put a known concentration of drug on the exterior surface of the glove and measured the amount that permeated the material after a given time, the new device also incorporated a mechanical stretching procedure to mimic the stretching that would occur in normal use. In each case the results are expressed as nanograms per cm2
per minute.
There were also other differences, Professor Wallemacq points out. For example, testing can be performed at 25°C, 37°C or 43°C. These temperatures are relevant because some types of colorectal surgery involve direct (intraperitoneal) infusion of oxaliplatin at 43°C (hyperthermic intraperitoneal chemotherapy, HIPEC). This approach delivers high peritoneal and tumour concentrations of the drug with limited systemic absorption. It is much more effective than oral or intravenous administration. However, the surgeon’s (gloved) hands can also be exposed to the drug solution, and therefore testing of glove permeability at this temperature is important, he explains.
Another aspect of the new assessment method is pre-treatment of the glove material with alcohol. Most practitioners will use an alcohol-based product at some stage in an aseptic procedure, usually for hard-surface disinfection or for skin sanitisation. Alcohol can denature the external layer of glove material and this could make it more permeable to cytostatic agents, says Professor Wallemacq. Thus, incorporating this step into the test process makes the conditions particularly stringent – but realistic. In one study 13 different gloves, made from natural rubber latex, vinyl, nitrile and neoprene, were tested with 13 cytostatic agents.1
The results showed that vinyl
gloves were the most permeable – after 15 minutes four of six test drugs had permeation rates greater than 10ng per cm2
per minute.
In general, gloves made from the other three materials presented a more robust barrier. All materials showed “low but significant permeability” to at least one drug after 60 minutes. Different gloves made of the same material showed different permeabilities. Liposolubility of the drugs used also appeared to play an important role; for example, carmustine (highly liposoluble) permeated the widest variety of materials.
What this means in practice, according to Professor Wallemacq, is that it is critically important to know how gloves perform when making purchasing decisions – especially when a hospital is
buying gloves to protect its personnel. “One glove is not necessarily the same as any other glove”, he emphasises. Moreover, these findings could be relevant to a number of other products that can be hazardous to personnel when exposure occurs on a continuous basis. Examples include antiviral agents, such as ganciclovir, which can penetrate the skin, and a number of dyes and other products that are used in molecular biology.
Finally, there are still unanswered questions in this field, Professor Wallemacq says. “We need a better understanding of the ideal frequency of glove changes - the current recommendations are not evidence- based. It could also be important to test the permeation of other non-drug chemicals through gloves.”
Professor Wallemacq concludes that now could be the time for a consensus view on a new standard for the permeability of gloves. “We have much more sensitive analytical methods than those that were available ten years ago and we can detect very small quantities of substances so we should probably demand a more rigorous standard”, he says. ●
Reference 1. Wallemacq PE, Capron A, Vanbinst R, Boeckmans E, Gillard J, Favier B. Permeability of 13 different gloves to 13 cytotoxic agents under controlled dynamic conditions. Am J Health-Syst Pharm 2006; 63: 547-556
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