Botox May Affect the Brain

A study now shows that Allergan Incorporated’s Botox, or botulinum neurotoxin type A, a wrinkle remedy, may move from the site of the injection to the brain. On April 2nd a study published in the Journal of Neuroscience claimed that botulism was found in the brain stems of test rats. Scientists had previously injected these rats’ whisker muscles with the botulism toxin, and tests of their brain tissue revealed these surprising results.

The authors of the study wrote that this neurotoxin may change the circuitry of the spinal cord as well as interrupt communication via nerve cells. Matthew Avram, the director of Massachusetts General Hospital’s Dermatology, Laser and Cosmetic Center claims that the study may not be a certain prediction of what happens in people due to the fact that human physiology deviates from rat and mouse physiology, but he does think the idea needs focused follow-up. If it is, in fact, being transmitted to the central nervous system, there may be big problems, but as Avram says, “this treatment has been used on millions of people for years, and we’re not seeing major central nervous system uses with it.”

This could affect millions, however, due to the popularity of the treatment. With $1.21 billion in sales last year, Botox is the company’s most popular and biggest selling product. It was approved in 1989 and originally was fashionable for celebrities. Since then, it has expanded into the middle class market. Currently Botox and Myobloc, a product from Solstice Neurosciences Incorporated, are being investigated as causes of botulism, an illness with symptoms of weakened muscles.

A spokeswoman from Allergan, Caroline Van Hove says that more work is necessary because the study contradicts previous findings and it lacks a conclusion. In a statement, Van Hove said, “The authors used a laboratory preparation of botulinum toxin and did not use Botox, and data suggest that different preparations of botulinum toxin react differently in both the laboratory and in clinical practice.”

Chief medical officer of Solstice Neurosciences Edgar Salazar-Grueso claims that Myobloc is a type B neurotoxin and a different type of botulinum than the one studied. According to Salazar-Grueso, studies have already been published in reference to the migratory behavior of toxin A. In monkeys, toxin A migrates more than B. Monkeys are more human-like than rodents, which makes these new findings consistent.

In the study, botulism toxin was injected into one side of each rodent’s hippocampus and into their visual center, or the superior colliculus, as well. The toxin proceeded to either migrate from one side of the hippocampus to the other or migrate to the eyes of the animal. Effects of the injection were still evident six months after the fact, according to scientists.

Warnings are issued with the prescribing literature for both Myobloc and Botox about possible breathing and swallowing difficulties. The FDA is concerned that the new data may make the severity of these warnings increase. The drugs might be life-threatening when used in patients with neuromuscular disorders.

Many of the cases already reviewed by the FDA which caused the warnings to be issued involved children who received injections in order to treat spasms associated with cerebral palsy. This use of the drug is not currently FDA approved, and the dosage is generally about 10 times more than the usual cosmetic dose. .

Matthew Avram is skeptical of linking this study to the previous problems with the FDA. He stated, “Those tend to be very young children with massive doses. I don’t know that this study relates to that.”

On the Net:

Allergan Incorporated

Journal of Neuroscience

Massachusetts General Hospital