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What is Botox®
Botulin toxin, sold commercially under the brand name Botox®, is an exceptionally potent neurotoxin that has found a variety of remarkable uses in modern medicine. It is also the most popular nonsurgical medical cosmetic treatment in the UK and USA.
A nerve with an enlarged view of the nerve endings, receptors on the muscle, and acetylcholine either released or blocked by Botox. Image courtesy of the FDA.
Botulinum (botulinus) toxin is the toxic compound produced by the bacterium Clostridium botulinum. The terms Botox® and Dysport® are trade names and should not be used generically to describe the neurotoxins produced by Clostridia species. There are seven serologically distinct toxin types, designated A through G; 3 subtypes of A have been described. The toxins incorporate an enzyme (a protease) that attacks one of the fusion proteins at a neuromuscular junction, preventing vesicles from anchoring to the membrane to release acetylcholine. By inhibiting acetylcholine release, the toxin interferes with nerve impulses and causes paralysis of muscles in botulism. The toxin is a two-chain polypeptide with a 100-kDa heavy chain joined by a disulphide bond to a 50-kDa light chain.
It is possibly the most acutely toxic substance known, with a lethal dose of about 200-300 pg/kg, meaning that somewhat over a hundred grams could kill every human on earth (for perspective, the rat poison Strychnine, often described as highly toxic, has an LD50 of 1 mg/kg, or 1 billion pg/kg). It is also remarkably easy to come by: Clostridium spores are found in soil practically all over the earth. Food-borne botulism usually results from ingestion of food that has become contaminated with spores (such as a perforated can) in an anaerobic environment, allowing the spores to germinate and grow. The growing (vegetative) bacteria produce toxin; ingestion of preformed toxin causes botulism, not ingestion of the spores or vegetative organism. Infant (intestinal) and wound botulism both result from infection with spores which subsequently germinate, resulting in production of toxin and the symptoms of botulism.
Researchers discovered in the 1950s that injecting overactive muscles with minute quantities of botulinum toxin type A decreased muscle activity by blocking the release of acetylcholine at the neuromuscular junction, thereby rendering the muscle unable to contract for a period of 4 to 6 months.
Alan Scott, a San Francisco ophthalmologist, first applied tiny doses of the toxin in a medicinal sense to treat crossed eyes and uncontrollable blinking, but a partner was needed to gain regulatory approval to market his discovery as a drug. Allergan, Inc., a small pharmaceutical company that focused on prescription eye therapies and contact lens products, bought the rights to the drug in 1988 and quickly received FDA approval in 1989. Allergan renamed the drug Botox®.
Currently, Botox® is finding enormous additional potential in several therapeutic areas including the treatment of migraine headaches, cervical dystonia (a neuromuscular disorder involving the head and neck), blepharospasm (involuntary contraction of the eye muscles), and severe primary axillary hyperhidrosis (excessive sweating). Other uses of botulinum toxin type A that are widely known but not approved by FDA include urinary incontinence, anal fissure, spastic disorders associated with injury or disease of the central nervous system including trauma, stroke, multiple sclerosis, or cerebral palsy and focal dystonias affecting the limbs, face, jaw, or vocal cords. It is also used off label for the treatment of TMJ, but a side effect in some patients is a jaw left too weak to chew solid food for about 3 months after the injection. Treatment and prevention of chronic headache and chronic musculoskeletal pain are emerging uses for botulinum toxin type A. In addition, there is evidence that Botox® may aid in weight loss by increasing the gastric emptying time.
At left, a patient with blepharospasm before injection with Botox is unable to open her eyes due to abnormal muscle contractions. At center, still pre-injection, she uses her fingers to keep her eyes open. At right, after injection, her eyes stay open without difficulty. Image courtesy of the FDA and Joseph Jankovic, M.D., professor of neurology, Baylor College of Medicine, Houston, Texas.
Cosmetic benefits of Botox® were quickly realized when the frown lines between the eyebrows appeared to soften following treatment for eye muscle disorders. The increased potential of Botox® as a cosmetic treatment led to clinical trials and subsequent FDA approval in April 2002.
Plastic surgery events known as Botox parties — also seminars, evenings and socials — are a key element of Botox marketing in much of the United States. The gatherings are thought to be a convenient means of providing Botox treatments more economically, and may help reduce the anxiety that normally goes along with getting an injection. Doctors are finding that treating people in groups allows them to make the procedure more affordable to their patients.
Here's how a "party" typically works: A group of often nervous, but excited, middle-aged men and women mingle in a common area. Sometimes refreshments are served. One by one, as their name is called, each slips away for about 15 minutes to a private exam room. He or she pays a fee and signs an informed consent agreement. Anesthesia is rarely needed, but sedatives and numbing agents may be available. The practitioner injects about one-tenth of a teaspoon of toxin into specific muscles of the forehead most often targeted for the effect. The person then rejoins the group.
The FDA is concerned that Botox has the potential for being abused. The ASAPS recently reported that unqualified people are dispensing Botox in salons, gyms, hotel rooms, home-based offices, and other retail venues. In such cases, people run the risks of improper technique, inappropriate dosages, and unsanitary conditions.
The FDA recommends that Botox Cosmetic be injected no more frequently than once every three months, and that the lowest effective dose should be used.
Sources: Wikipedia » Botox & "Botox Cosmetic: A Look at Looking Good" by Carol Lewis in FDA Consumer
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