The pill, called ubrogepant (Ubrelvy) is for the immediate treatment "of migraine with or without aura [a sensory phenomenon or visual disturbance] in adults," the agency said in a news release.
Ubrogepant is not to be used to prevent migraines, the FDA said, only to treat an attack once it strikes.
"Migraine is an often disabling condition that affects an estimated 37 million people in the U.S.," said Dr. Billy Dunn, acting director of the Office of Neuroscience in the FDA's Center for Drug Evaluation and Research. "Ubrelvy represents an important new option for the acute treatment of migraine in adults, as it is the first drug in its class approved for this indication."
According to the FDA, approval came after the results of two studies involving more than 1,400 adults.
"In both studies, the percentages of patients achieving pain freedom two hours after treatment [defined as a reduction in headache severity from moderate or severe pain to no pain] and whose most bothersome migraine symptom (nausea, light sensitivity or sound sensitivity) stopped two hours after treatment, were significantly greater among patients receiving Ubrelvy at all doses compared to those receiving placebo," the FDA said.
Ubrogepant belongs to a new class of medications called CGRP inhibitors that has come to the market in the past year.
CGRP is a small protein released by the trigeminal nerve during migraine attacks. It's believed to play a key role in generating migraine misery, explained Dr. Richard Lipton, who directs the Montefiore Headache Center at the Albert Einstein College of Medicine in New York City.
The three approved CGRP inhibitors are all injection drugs that are used regularly, to prevent migraine attacks.
Ubrogepant is different because it's a tablet that treats migraines in progress. Another oral "gepant," called rimegepant, is also in the pipeline. Data on both drugs have been submitted to the FDA for approval, according to the companies developing them.
Lipton's group published its own study on the drug, released last month.
The study involved nearly 1,700 patients and found that the pill worked better than a placebo pill at halting migraines in progress. Ubrogepant beat placebo treatment in easing pain and other migraine symptoms, such as nausea and sensitivity to light or sound.
Of patients who used the real drug to treat a migraine attack, 22% of those on a higher dose were pain-free within two hours. That compared with 14% of the placebo group. Similarly, 39% of ubrogepant users were free of their "most bothersome" symptom within two hours, versus 27% of placebo users.
The study, funded by drug's maker, Allergan, was published Nov. 19 in the Journal of the American Medical Association.
According to Lipton, the new gepants could make a "big difference" for certain migraine patients.
They include people who do not get relief from current acute treatments, and those who cannot take the medications because of side effects or safety concerns, Lipton said.
Right now, medications called triptans are the standard treatment for more severe migraine attacks. The drugs, which came out in the 1990s, stop migraines by stimulating receptors for the brain chemical serotonin, which reduces inflammation and constricts blood vessels.
Triptans also have side effects -- like numbness, dizziness and sleepiness -- that can make them difficult to take.
Gepants work through a "novel mechanism," Lipton said, which means they might help some patients who do not respond to triptans. And they do not constrict blood vessels.
Lipton has financial ties to both Allergan and Biohaven Pharmaceuticals, maker of rimegepant.
It will be "exciting" to have new options for patients who cannot take triptans, said a neurologist who was not involved in the study.
"There haven't been any new acute treatments in a long time," Dr. Rachel Colman, of Mount Sinai's Icahn School of Medicine in New York City, said in November.
Questions do remain, Colman pointed out. The latest trial tested the effects of only a single treatment, and it's not clear how consistent patients' responses will be over time, she said.
Long-term safety and side effects are also unknowns -- though, Colman said, "so far, the tolerability data looks good."
Nausea was the most commonly reported side effect in the JAMA study, affecting 2% of ubrogepant patients within two days of taking the drug.
In the United States alone, more than 37 million people suffer from migraines, according to the American Migraine Foundation. People with milder migraines may find relief with general pain relievers like naproxen and acetaminophen.
But for some migraine sufferers, Colman noted, "there's a significant need" for new tactics.