Petasites, tizanidine may prevent headache. (Herbal Product, Muscle Relaxant).
Also garnering attention were open-label studies of headache prevention using botulinum toxin type A injections, the antiepileptic agent topiramate, and the atypical antipsychotic agent quetiapine.
* Petasites. Dr. Richard B. Lipton, professor of neurology at Albert Einstein College of Medicine in New York, presented a 202-patient double-blind randomized trial of petasites, an extract from the plant Petasites hybridus, for migraine prophylaxis. After 4 months, patients receiving the herbal therapy had statistically significant reductions in the mean frequency of headaches, compared with baseline: The rate was 48% lower with petasites 75 mg b.i.d., 34% lower with petasites 30 mg b.i.d., and 26% lower with placebo.
Petasites is believed to prevent migraine by inhibiting peptidoleukotriene biosynthesis, possibly via calcium channel regulation. Petasites is marketed in the United States as Petadolex. Weber & Weber Biologische Arzneimittel, the German manufacturer of the herbal, sponsored the clinical trial. Dr. Lipton is a consultant to the company
* Tizanidine. This [[alpha].sub.2]-adrenergic agonist proved significantly more effective than placebo for headache prophylaxis in an 8 to 12-week double-blind trial involving 92 patients with chronic daily migraine, migrainous, or tension-type headache.
Headache index was the primary study end point. The index takes into account the number of headache days per month, the average headache intensity, and headache duration in hours. The index declined by 54% in the tizanidine group, compared with 19% with placebo, reported Alvin E. Lake III, Ph.D., of the Michigan Head Pain and Neurological Institute, Ann Arbor.
The median dosage of tizanidine used was 20 mg/day divided into three dosage intervals. But tolerability of the drug varied widely, ranging from 2 to 24 mg/day. And although the drug is usually thought of as a muscle relaxant, Dr. Lake doesn't believe that's the reason it helps prevent chronic daily headache. The relevant mechanism more likely involves inhibition of central [[alpha].sub.2] sensitization, he said.
The clinical trial was sponsored by Elan Pharmaceuticals, a company for which Dr. Lake has served as a consultant.
* Botulinum toxin. Dr. Eric J. Eross presented a pilot study in which 48 patients with episodic or chronic migraine headaches received botulinum toxin type A (BTX-A) in the standard 25-unit injection protocol used to treat facial wrinkles, supplemented by another 25-75 units injected into the cervical paraspinal muscles if tenderness was present.
At least a 50% reduction in disability was seen in 58% of patients at 3 months following the injections. In 40%, response was excellent, defined as a 75% or greater reduction in headache-associated disability. And 20% had a greater than 90% improvement in disability, reported Dr. Eross of the Mayo Clinic, Scottsdale, Ariz.
The best predictor of therapeutic response was the overuse of analgesics. Treatment response rate was 22% among the 20 migraine patients who overused analgesics, and 78% in those who did not.
The response rate was independent of the amount of BTX used. Moreover, injection of the cervical paraspinous muscles in patients with underlying tenderness didn't affect the response rate, a finding at odds with one popular theory of head pain.
Discussant Dr. Ninan T. Mathew, director of the Houston Headache Clinic, said a subset of migraine patients probably respond to BTX, but the treatment really isn't ready for prime time. Key unresolved issues include optimal dosing and injection placement. Dr. Eross agreed; based upon the favorable pilot study results, he and his colleagues at the Mayo Clinic are planning a placebo-controlled trial in more than 100 migraine patients.
* Topiramate. This broad-spectrum antiepileptic drug proved safe and effective for migraine prophylaxis in a 56-weeklong, 29-patient, open-label extension of a 20-week randomized placebo-controlled double-blind trial. The mean dosage of topiramate used in the open-label phase was 127 mg/day.
The mean monthly headache frequency in patients who'd been on topiramate through both the double-blind and openlabel phases fell 64%, from 4.67 to 1.77. For patients on the drug only for the 56-week open-label phase, headache frequency decreased by 46%, said Dr. David E. Hart of Upstate Neurology Consultants, Albany, N.Y.
The study was sponsored by Ortho-McNeil Pharmaceutical.
Elsewhere at the meeting, Dr. Mark Green said that although topiramate in the doses used for epilepsy typically results in weight loss, migraine prophylaxis doses are low enough that the drug usually winds up being weight-neutral.
Still, a weight-neutral drug for migraine is attractive. Virtually all other antimigraine drugs have weight gain as a prominent side effect, according to Dr. Green, codirector of the headache center at the Columbia-Presbyterian Headache Center in New York.
* Quetiapine. Seven of 17 patients with severe migraine reported decreased headache severity during 3 months of open-label quetiapine at an average dosage of 75 mg/day An equal number of patients reported decreased migraine frequency Nine experienced shorter duration of attacks. Six patients had a significant reduction in disability because of their headaches as evidenced by a marked decline in their Migraine Disability Assessment Score.
On the other hand, six patients discontinued quetiapine because of adverse events, mostly somnolence, reported Dr. Jan L. Brandes of the Nashville (Tenn.) Neuroscience Group.
Quetiapine is a new atypical antipsychotic agent that acts as an antagonist to multiple neurotransmitters in the brain, some of which may figure in migraine. Unlike traditional antipsychotics, quetiapine has less than a 1% incidence of extrapyramidal symptoms. It doesn't have any significant effect on cardiac QT interval either, she noted, adding that placebo-controlled double-blind studies on quetiapine for migraine prophylaxis seem warranted by the limited experience to date.
Dr. Brandes is a consultant to and member of the speakers' bureau for AstraZeneca, sponsor of the open-label study
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|Publication:||Clinical Psychiatry News|
|Date:||Jan 1, 2003|
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