It's the first in a new class of long-acting drugs for preventing migraines. Three other shots are expected to win approval by next year, and several pills for preventing migraines are being tested.
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The drug erenumab works against migraines to block pain signals by targeting a receptor for calcitonin gene-related peptide (CGRP). This peptide, according to the American Academy of Neurology, is responsible for transmitting those migraine pain signals and inducing pain. Erenumab works to bind to the nerves to which the peptide would usually bind, blocking the pain.
To test the effectiveness of the drug, the researchers examined 246 people who are considered "more difficult to treat," study author Uwe Reuter said in a news release. The participants were given injections of either 140 milligrams of erenumab or a placebo once a month for three months.
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Of the 246 participants, nearly 40 percent had been unsuccessfully treated with two other medications for migraine, 38 percent with three medications and 23 percent with four medications.
Before the study, participants on average experienced nine migraine headaches per month and used a migraine drug to stop the attack five times per month, on average.
After the three months, those treated with erenumab were nearly three times more likely to have reduced the number of days with migraine by 50 percent or more than those in the placebo treatment group.
The erenumab group also experienced a greater average reduction in the number of days they had migraines at all and days they required medication to stop the headaches.
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None of the participants taking erenumab stopped taking the drug due to side effects, which is a primary reason many taking migraine medications typically stop treatment.
One limitation, researchers noted, is that they only followed the participants over a three-month period.
“Our results show that people who thought their migraines were difficult to prevent may actually have hope of finding pain relief,” Reuter said. “More research is now needed to understand who is most likely to benefit from this new treatment.”
According to the Global Burden of Disease Study, updated in 2013, migraine is the sixth highest cause worldwide for years lost due to disability, the World Health Organization reported. General headache disorders were third highest.
“There’s no current dedicated migraine prevention medication,” Dr. Michael R. Silver, an assistant professor in neurology at Emory University who was not involved in the study, told The Atlanta Journal-Constitution. “We borrow from other fields and use mostly anti-seizure medicines, blood pressure medicines or anti-depressants for migraine prevention.”
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To treat migraines, people usually take over-the-counter NSAIDs or dedicated triptans, a class of drugs first introduced in the 1990s. Side effects such as drowsiness, dizziness or slow-thinking, however, often stop individuals form continuing treatment.
But erenumabs are part of a very promising class of medicines, Silver said. “We’ve known CGRP have been involved in migraines for years and now, we’re finally coming out with medicines to address what is likely the root cause of migraine pain.”
While Silver worries the cost of the drug will be a huge problem, “this will hopefully usher in the new era of migraine treatment,” he said.
The long-term safety of Aimovig, also known as erenumab, hasn't been tested, and Amgen plans to track outcomes in women who become pregnant while taking it.
The Associated Press contributed to this report.