To print: Select File and then Print from your browser's menu --------------------------------------------------------------------------------------- Title: WCN: Zanaflex (Tizanidine) Provides Well-Tolerated, Effective Treatment for Chronic Headache URL: http://www.pslgroup.com/dg/1FEB86.htm Doctor's Guide June 20, 2001
LONDON, ENGLAND -- June 20, 2001 -- Results from a recent randomized double-blind, placebo-controlled clinical study may provide hope for millions of people who suffer from frequent or daily headaches. The data, presented today at the World Congress of Neurology, show that the drug tizanidine (Zanaflex®) significantly reduced the frequency, intensity, and duration of headaches in patients experiencing an average of 23 days of headache/month. Most (75 percent) had been suffering with chronic daily headache for three years or longer, and experienced a combination of both frequent migraines and chronic daily pain. Overall headache frequency for the group receiving tizanidine declined by an average of eight days/month (P<0.02), and severe headaches dropped by 55 percent (P<0.02). Average headache intensity (P<0.01), peak intensity (P<0.002), and mean headache duration (P<0.01) each declined by at least 33 percent, with mean duration dropping from 6.8 to 4.4 hours/headache. Based on a headache index combining frequency, average intensity, and duration, the average percentage improvement was 51 percent for those receiving tizanidine, compared to 34 percent for placebo (P<0.0025). Patients were only allowed to use a limited amount of analgesic and abortive medication, and could not add new abortives once they entered the single-blind baseline phase of the study. Changes in headache intensity and duration were not due to more frequent use of abortives, which actually declined during the course of the study. Patients receiving tizanidine also rated their overall headaches as significantly better at the end of the study than those who received placebo (P<0.007). "Medical literature focused on chronic daily headache (CDH) is limited, so most of what we know about treatment strategies is based on anecdotal information," says Alvin E. Lake III, Ph.D., Director of the Behavioral Medicine Division at the Michigan Head Pain and Neurological Institute and study co-investigator. "This study is important because it gives clinicians scientific evidence regarding a new approach to treating an often difficult-to-treat condition." The multicenter study involved co-investigators including Joel R. Saper, M.D., FACP (Director of the Michigan Head Pain and Neurological Institute), Alvin E. Lake III, Ph.D. (Division Director, Behavioral Medicine, Michigan Head Pain & Neurological Institute), Paul K. Winner, D.O. (Director, Premier Research Institute/West Palm Beach Headache Center, West Palm Beach, Florida), and others. Tizanidine hydrochloride is an alpha(2)-adrenergic agonist that inhibits the release and effectiveness of norepinephrine at both central sites (e.g., the locus coeruleus) and the spinal cord. It acts as a central muscle relaxant and exhibits antinociceptive effects with little or no interaction with serotonin, dopamine, or GABA receptors. Ninety-two patients completed a four-week single-blind placebo baseline, with 45 then randomly assigned to tizanidine and 47 to placebo. Forty-four of the tizanidine group and 41 who were given placebo then completed all 12 weeks of planned treatment. Dosing was titrated from 2mg at bedtime to a median daily dose of 20mg during the treatment weeks 9-12 (mean = 18.4, SD = 6.4, range = 2-24, divided over three doses per day). "Not only did treatment with tizanidine reduce the amount of analgesic required by patients, it seemed to work more effectively on reducing the frequency of the most severe headaches, which dropped by 55 percent compared to a 32 percent decline in the overall frequency of headaches," said Dr. Lake. "A post-hoc analysis found that those who unquestionably met IHS criteria for migraine were just as likely to be treatment responders as those with chronic tension-type headache." Mild-to-moderate adverse events reported by more than 10 percent of the patients that were significantly more common in the tizanidine group included somnolence, dizziness, insomnia, dry mouth, and asthenia. Past research with tizanidine has shown elevated liver enzymes in a small minority of patients, which return to normal when the drug is discontinued. Liver enzymes should be monitored. The complete analysis of this data supports recently published preliminary results from an open-label study (Saper JR, Winner PK, Lake AE. An open-label dose-titration study of the efficacy and tolerability of tizanidine hydrochloride tablets in the prophylaxis of chronic daily headache. Headache 2001; 41:357-368).
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