Botulinum toxin has become a new treatment option for hyperhidrosis. Elan Pharmaceuticals says that it is working on a reformulation of Myobloc, its Type B toxin. Also, Ipsen, Ltd. of Great Britian has moved into phase 3 trials with a new form of Type A called Dysport.
"It'll probably be released in 2005 — a competitive challenge to Botox (Allergan)," Dr. Sadick notes.Cosmetic dermatologists have migrated south and now frequently use botulinum toxin to treat signs of aging on the lower third of the face (i.e. to angle the lips upward) as well as on neck bands. They are also combining the toxin with light therapies and fillers. Furthermore, new research indicates botulinum toxin can be reconstituted without being frozen first.
Says Dr. Sadick: "It can stay refrigerated for six weeks without losing much of its potency."
A vs. B Dr. Sadick, who is a clinical professor of dermatology at the Weill Medical College at Cornell University, estimates that he has administered hundreds of thousands of units of botulinum toxin. He describes Type A as the "gold standard" for treatment of hyperkinetic facial wrinkles. Full resistance is rare. Results last from 12 to 16 weeks.
Studies of Myobloc indicate that it has a very rapid onset, reaching efficacy in less than three days. The mean duration of action for doses of 2,400 units is 9.6 weeks, and preliminary results from a study evaluating doses of 3,000 units suggest a mean duration of 11.2 weeks.
"More studies of Myobloc are needed to evaluate the optimal dose in terms of efficacy, duration and side effects," Dr. Sadick says.
Potentially, Myobloc could be used in patients who are resistant to Type A botulinum toxin or for those who want rapid onset or seek a more diffuse, uniform freeze of the frontalis area. Because Myobloc doesn't have to be reconstituted, it can also be useful to have on hand for touch-up procedures.
Botox comes as a vacuum-dried preparation in vials of 100 units, requiring reconstitution. Myobloc, on the other hand, is premixed in three (overfilled) vial sizes. A 2,500-unit vial actually contains 4,100 units, the 5,000-unit vial has 6,800 units, and the 10,000-unit vial has 12,650 units.
"This means more bang for the buck," Dr. Sadick says.
Because Myobloc is less concentrated and tends to diffuse more, he tends to make fewer injections. When used in combination with Type A, the effect is additive, not synergistic.
Types A and B have similar side effects. Technique-related complications include ptosis of the brow or lid, diplopia, bruising, a decrease in tearing, infection and contour irregularities. Other adverse events include idiosyncratic reactions, such as transient numbness and headaches, muscle spasms, myasthenia and immunologic reactions.
The "golden rules" for avoiding complications, according to Dr. Sadick, are:
Disclosure: Dr. Sadick consults with many pharmaceutical and laser companies, including Allergan.