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Butterbur for migraine prophylaxis.

History of Use

Medicinal properties have been ascribed to the peculiar plant Petasites hybridus, common butterbur, since the first-century Greek physician Dioscurides used its pounded leaves to treat skin ulcers. The leaves can reach a diameter of 3 feet and were said to resemble the large felt hat (Greek petasos) worn by shepherds.

Powder made from the roots was used to treat fevers and plague, as was noted by John Gerard in his Herball (1633): "The roots of Butter-burre stamped with ale, and given to drinke in pestilent and burning fevers, mightily cooleth and abateth the heat therof. The roots dried and beaten to powder, and drunke in wine, is a fouraigne medicine against the plague and pestilent fevers, because it provoketh sweat and driveth from the heart all venome and ill heate ..." The English name butterbur is thought to derive from the practice of wrapping butter in the leaves during warm weather.

Other traditional uses for extracts of P. hybridus include dysmenorrhea, back pain, cough, asthma, and pain in the urinary and gastrointestinal tracts.

In Germany, a standardized extract, Petadolex (Weber & Weber, Inning, Germany) is regulated by the government health authority as a drug. In the United States, petasites extract is marketed as a dietary supplement and therefore is unregulated.

Actions and Effects

Extracts of petasites are thought to exert anti-inflammatory and analgesic effects through inhibition of prostaglandin and leukotriene synthesis. Leukotrienes have been implicated in the migraine inflammatory cascade, as was suggested by a reduction in attacks among patients with comorbid asthma given the leukotriene inhibitors montelukast and zafirlukast.

The sesquiterpene ester petasine also inhibits the intracellular release of calcium, which may have vasodilating and relaxing effects on smooth muscle.

Clinical Findings

Because anecdotal reports and a small study of 60 patients suggested efficacy in migraine prophylaxis, researchers in New York and Germany undertook a double-blind, randomized, placebo-controlled study comparing two doses of petasites extract with placebo.

Patients were aged 18-65 years and met the criteria of the International Headache Society for migraine with or without aura. They had two to six attacks per month but took no prophylactic medications for the 3 months prior to study entry.

Of the 233 patients who were randomized to 50 mg or 75 mg petasites extract twice daily or placebo, 202 completed the 16-week study.

The primary end point was the reduction in the mean number of migraine attacks per month. In the 75-mg petasites group there was an average reduction of 45% in the number of attacks per month, compared with 28% for the placebo group, a difference that was statistically significant (Neurology 2004;63:2240-4). The 32% decrease in the 50-mg petasites group was not statistically different from placebo.

Patients who experienced a 50% reduction in mean attack frequency per month were considered responders. In the 75-mg petasites group, 54% of patients achieved this by week 4, as did 60%, 71%, and 68% by weeks 8, 12, and 16, respectively, percentages that all differed significantly from placebo.

The authors noted that the magnitude of the treatment effect was "substantial" and "broadly comparable with results obtained with prescription preventive medications." Lead author Richard B. Lipton, M.D., professor and vice chair of neurology, Albert Einstein College of Medicine, New York, told this newspaper, "we were pleased and surprised by the strong effects."

Another herbal product, feverfew, also is commonly used by migraineurs. While there have been no head to head studies comparing petasites to feverfew for migraine prophylaxis, Dr. Lipton said, "in my judgment the evidence for the efficacy of petasites is better than the evidence for feverfew."

Safety Concerns

The most common adverse event seen in Dr. Lipton's double-blind trial was a gastrointestinal disturbance (burping). There were five serious adverse events, including food poisoning and basal cell carcinoma, none of which were considered to be related to treatment. No changes were seen in blood pressure, heart rate, or liver function tests throughout the study.

Commercial petasites extract has been available in Germany since 1988, and an estimated 500,000 patients have used the product. Post-marketing assessments and a long-term database maintained by the manufacturer have identified 115 suspected adverse events, representing an overall event frequency of 0.02%. No new long-term events, other than those found in the short term studies, have been reported.

The most important safety concern with butterbur is that patients never consume any part of the plant except as a commercial preparation such as Petadolex. The plant contains pyrrolizidine alkaloids, which are bitter tasting and serve to protect the plant from being eaten by animals.

These alkaloids can be metabolized to toxic or carcinogenic intoxicants that, in severe cases, can cause Budd-Chiari syndrome and malignant epithelial hepatic tumors (Bioforce Monograph, Roggwil, Switzerland, May 2002). Commercial preparation involves extraction with liquid carbon dioxide that removes the pyrrolizidine alkaloids to a detection level below 0.1 parts per million, a process meeting the requirements of the German Health Authority

Dr. Lipton also pointed out that there is no evidence that petasites extract works in the acute migraine setting. No formal interaction studies have been done between petasites and standard rescue medications such as analgesics and triptans, but patients using the herbal preparation for prophylaxis commonly also use these rescue medications, Dr. Lipton said.

* Extracts of Petasites hybridus have a long history of use for applications that range from plague to asthma and migraine.

* A recent blinded, randomized trial found substantial, statistically significant decreases in frequency of migraine attacks among patients taking a standardized extract.
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Title Annotation:Alternative medicine: an evidence-based approach
Author:Walsh, Nancy
Publication:Family Practice News
Date:Mar 15, 2005
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