In that same year, FDA approved dexfenfluramine, and doctors rushed to combine it with phentermine. I ndividual health care providers observing individual patients triggered the events that eventually led to the drugs' being yanked off the market. The woman also had been taking fen-phen. Her surgeon had noted that her valves appeared glistening white, a telltale sign of injury by a migraine medication known as ergotamine. Yet the patient had never taken that drug.
Ergotamine is similar to the brain chemical called serotonin.
The Mayo researchers knew that fenfluramine and phentermine alter the way the body handles serotonin, and they wondered whether this could be the mechanism by which the diet drugs harmed the heart. Connolly, Crary, and their colleagues compiled 24 cases of women who had taken fenfluramine in combination with phentermine. Most were in their thirties and forties and had symptoms of heart valve disease, including shortness of breath, fatigue, and a heart murmur. Their echocardiograms showed they had leaky valves. Normally, heart valves allow blood to go in only one direction, but when damaged, they let some of the blood slosh backward into the heart.