From This months Skin & Allergy News.
Dry mouth, dry eyes
Botulinum Toxin B Not Panning Out as Wrinkle Treatment
Kathryn DeMott
Senior Writer
PARIS — Evidence continues to mount that Myobloc may not be an efficient treatment for wrinkles.
Instead it appears that Botox (botulinum toxin A), the only botulinum toxin approved in the United States for cosmetic purposes, lasts longer, is less expensive,
and involves fewer side effects than does Myobloc (botulinum toxin B).
All of which bodes poorly for dermatologists and patients hankering for some healthy market competition to help drive down the costs of toxin.
In a placebo-controlled study presented at the 20th World Congress of Dermatology, 15 patients had their crow's-feet treated with 1,500 U of Myobloc; 5
patients received an equal number of injections of placebo.
After 30 days, placebo-treated patients were treated with Myobloc and followed under the same protocol as the active treatment group, reported Dr. Leslie S.
Baumann, director of cosmetic dermatology at the University of Miami.
The peak effect of Myobloc was seen at 30 days, but by 49 days, patients reported seeing wrinkles start to reappear. Investigators evaluating patients at
30-day intervals confirmed a loss of correction at 60 days of follow-up, and all patients had returned to baseline between days 90 and 120.
By contrast, in the clinical trial on which Botox's cosmetic indication was approved, injections for glabellar lines took 1 week to reach their peak affect, and
correction results were still reported up to 4 months later.
In the Myobloc study, dry mouth was reported by 45% of participants (9 of 20); 80% of these events were most likely related to the study drug.
Dry eyes were reported by 25% of study participants (5 of 20), a side effect that was thought to be related entirely to the study drug. One patient experienced
impaired eye motion.
The dry mouth was particularly acute among patients, Dr. Baumann told SKIN & ALLERGY NEWS.
These patients constantly reported wanting to drink water and actually had severe sensations of burning in their throat and on their lips. Most patients who
experienced the dry mouth said that they would not have the treatment again because it wasn't worth it. None of the patients taking placebo reported this side
effect.
Dr. Baumann added that none of the patients she treats with Botox have experienced such dry mouth problems.
Instead, headache is the most commonly associated side effect of Botox, occurring among about 13% of recipients, followed by temporary drooping of the
eyelid with a 3% incidence, and flu symptoms in 2%.
Interestingly, the same mechanism that causes dry mouth may explain its effectiveness for hyperhidrosis, she said. Dr. Baumann is conducting another study for
its use among patients with excessive sweating and saliva production.
And then there's the issue of expense.
At the 1,500-U dose used in the study, the cost to the physician for treating crow's-feet worked out to about $111 per side of the face, compared with $47 for
the same treatment with Botox, Dr. Baumann said, based on a cost of 7.4 cents/U for Myobloc versus $3.90/U of Botox.
In general, the cost of treating a patient with either product balances out when the ratio of units used is about 1:50, Botox to Myobloc.
Yet to achieve wrinkle correction in this study, a ratio of more like 1:250 was needed, she commented.
This study was funded by an educational grant from Elan Pharmaceuticals, manufacturer of Myobloc.
Dr. Baumann accepts research funding from and is on the advisory boards of both Elan Pharmaceuticals and Allergan Inc., the manufacturer of Botox. |
