Frequently asked questions: Medical gloves and Endotoxin Testing.

What are Endotoxins?
Why are endotoxins important?
Are there any recognised limits for endotoxins?
Why does SMTL recommend testing 3 batches ?
References

What are Endotoxins?

Dictionary definition: A heat-resistant pyrogen (specifically a lipopolysaccharide) found in the cell walls of certain pathogenic (disease-producing) bacteria.

Endotoxins are part of the outer cell wall of bacteria, invariably associated with Gram-negative bacteria as constituents of the outer membrane of the cell wall. Endotoxins are heat stable (boiling for 30 minutes does not destabilize endotoxin), but can be degraded by certain powerful oxidising agents (superoxide, peroxide and hypochlorite).

Therefore, even if a medical device has been sterilised, residual endotoxins may still be found on the device.
(This question last updated on the 9-4-97, by pete@smtl.co.uk)

Why are endotoxins important?

Endotoxins are toxic to most mammals, and produce the same range of biological effects in the animal host.

Injection of endotoxin into experimental animals causes a range of reactions, including fever, changes in white blood cell counts, hypotension and shock.
(This question last updated on the 9-4-97, by pete@smtl.co.uk)

Are there any recognised limits for endotoxins?

At present, there are no requirements in the UK or Europe for endotoxin levels on Natural Rubber Latex (NRL) medical gloves. However, the draft European standard (prEN 455 part 3) for medical gloves states that if the gloves are to be labelled "low endotoxin content", then the upper process limit shall be labelled on the packaging.
(This question last updated on the 9-4-97, by pete@smtl.co.uk)

Why does SMTL recommend testing 3 batches ?

For new products and regular testing SMTL recommend preliminary testing followed by inhibition/enhancement studies on three separate lots before routine analysis. This is based on the USP and FDA recommendation of testing a minimum of 3 and a maximum of 10 batches for both inhibition/enhancement and routine testing. Extracts can be tested separately or pooled (which is cheaper).

For one-off testing, a single sample preliminary validation can be carried out and the endotoxin result used as an indication of the content.
(This question last updated on the 9-4-97, by pete@smtl.co.uk)

References

A useful Internet document (on which much of the above is based) can be found at http://www.bact.wisc.edu/Bact330/lectureendo, part of the University of Wisconsin-Madison Bacteriology Home Page.
(This question last updated on the 9-4-97, by pete@smtl.co.uk)

This file is one of a number at SMTL's WWW site, dealing with frequently asked questions (FAQ's) on medical disposables and dressings. If there are any questions you would like to see answered in this FAQ file, please contact Pete Phillips at SMTL.

This site was originally set up with the aid of sponsorship from the Value for Money Unit, Welsh Office and an educational grant from Sophos Convatec.