Lethal Dose Testing of Botulinum Toxin
A new test has been developed by the makers of Botox.
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Botulinum toxin, produced by bacteria, is one of the most powerful poisons known. It is responsible for the potentially fatal food poisoning called botulism. Its effect is to weaken or totally paralyse muscle activity, by preventing muscles from accepting signals sent by the nerves. In this way, small doses of toxin injected into the face cause wrinkles to be smoothed out.
The toxin was originally used for medical purposes, to treat squinting. Since then, more than 50 other medical uses have been found for the toxin, including the treatment of facial spasms, migraine, Parkinson's disease, multiple sclerosis and back pain. However, it is the cosmetic use that has seen the greatest growth recently. About 30-50 per cent of all Botox produced is used cosmetically. Between 1998 and 2002, cosmetic use in the United States increased by 1500 per cent. A similar pattern can be seen in the UK.
The cosmetic use of botulinum toxin (the most well known brand of which is Botox(R)) is lucrative. Current UK prices for treatment range from £150 for an injection between the eyebrows to £450 for treatment of the whole forehead. This provides at least a 10-fold return on the price paid by the treatment provider for the toxin.
It is important to know the exact potency of the toxin, in order to administer doses that are both safe and effective for the envisaged treatment. However, because the toxin is a biological product, the potency varies from batch to batch. This means that each batch has to be tested afresh.
The test is currently done by injecting mice with the toxin. The potency is then calculated from the dose required to cause paralysis or death. The lethal dose that kills 50 per cent of the animals (LD50) in a test group is used to set safe doses for human use. LD50 testing is banned in some countries and has become far less acceptable in other countries.
It is a paradox that the widespread opposition to one-off testing of cosmetics has seemingly not been transferred to the testing of botulinum toxin for cosmetic use; a procedure that has to be repeated on each new batch that is produced. At least some of this testing is carried out in the UK, because the Dysport brand of botulinum toxin is produced in this country at Porton Down.
It might be argued that toxin used cosmetically is simply the surplus from batches produced for medical use, where different ethical criteria is applied. However, that is not the case, because the toxin can be stored for decades. Beauty clinics are driving an increase in the overall production and testing of botulinum toxin. There is no excuse for the fact that animals are being subjected to painful and distressing procedures in order to satisfy human vanity and neurosis.
Clearly, there are important medical reasons for the continued use of botulinum toxin. Therefore, it is vital for new test systems to become available, which will avoid the use of animals. Some methods have already been developed, but a greater effort is required to optimise and validate them.
In an ideal world, a moratorium would be declared on the trivial, non-medical use of botulinum toxin until such time as it can be tested by humane methods. In reality, commercial opportunism and individual vanity will undoubtedly prevail over ethics, especially if public pressure is lacking. This sad fact adds even more urgency to the pressing need for valid non-animal alternatives to the currently used potency test.
FRAME has campaigned for changes to the way in which batches of botulinum toxin are tested in the US and Europe by considering the possibility of using isolated tissue preparations or in vitro studies.