New botox could reduce animal toxicology testing
Scientists have developed a new form of botox that lasts for months without the toxic side-effects of the current treatment used in the medical and cosmetic industries. Thanks to the low toxicity of the redesigned drug it could also potentially reduce the use of thousands of mice used in safety testing each year.
Botulinum toxin A, or botox as it is commonly known, is produced by the bacterium Clostridium botulinum. Although it is highly toxic, it can be administered safely in extremely small doses to treat painful muscle spasms and involuntary eye muscle contractions. It is produced commercially for these and other medical purposes and also increasingly for cosmetic applications. But due to its effect on the nerves that control movement, a high dose or a faulty batch can easily cause paralysis and even death.
Every batch produced has to be safety tested. The “mouse lethal dose 50” (LD50) test is usually used and involves injecting mice with the toxin to determine the dose which will kill half of the animals at a defined time-point. The test needs to be precise and so many animals are needed, usually over a hundred. The increasing popularity of botox for cosmetic purposes in particular has resulted in an alarming number of mice suffering this severe procedure.
By combining elements of the botox molecule and a second tetanus toxin produced by the bacterium Clostridium tetani, the scientists were able to develop a new molecule with improved medical properties, without the unwanted toxic effects.
Tests with a rat model of inflammatory pain showed that the botox element is able to block pain signals for months. Meanwhile the tetanus component of the new molecule vastly reduces the risk of paralysis and death by targeting it specifically to the nerves responsible for transmitting pain rather than the nerves that control movement.
Professor Davletov of the University of Sheffield, who led the study, said "A single injection of the new molecule at the site of pain could potentially relieve pain for many months in humans and this now needs to be tested. We hope that the engineered molecule could improve the quality of life for those people who suffer from chronic pain. We are now negotiating transfer of the technology to a major pharmaceutical company."
The new molecule could lead to a great reduction in the number of mice needed for toxicology testing if it is found to be as effective as traditional botox but without the dangerous toxic effects.