New Anti-Obesity Drug OK'd
WASHINGTON - Chronically fat Americans may get help in losing weight this summer when the nation's first new anti-obesity drug in more than 20 years goes on sale.
The Food and Drug Administration approved dexfenfluramine yesterday - despite objections of consumer advocates and some doctors, who fear it could cause brain damage or a dangerous lung disorder.
"These serious concerns have not been adequately addressed," Dr. Sidney Wolfe of the advocacy group Public Citizen wrote the FDA just hours before it cleared the drug.
But the FDA concluded that the brain damage so far has been found only in animals, and the lung ailment is very rare. Consequently, obese Americans can use dexfenfluramine by prescription longer than any other appetite suppressant, the agency ruled.
"It's a controversial issue," acknowledged Dr. James Bilstad, FDA chief of metabolic drugs. But "we believe the benefits outweigh the risks."
Obesity is defined as more than 20 percent over ideal weight. Related diseases such as high blood pressure, heart disease and diabetes kill 300,000 Americans a year.
Doctors typically urge patients to diet and exercise. But many who drop weight regain it.
Until now, patients could take amphetamines, which can be addictive, or the drug fenfluramine - but none are supposed to be used for more than several months because of potential side effects.
Fenfluramine was the last anti-obesity drug to gain government approval, in 1973.
Dexfenfluramine, a close chemical relative of fenfluramine, can be used indefinitely, although its label will warn that its safety and effectiveness hasn't been studied beyond a year's use.
The drug alters the brain chemical serotonin to make people feel full even if they're not. But it won't work for everybody, the FDA warned.
In one study, six of 10 patients who lost at least 4 pounds in the first month of dexfenfluramine treatment went on to lose up to 10 percent of their body weight by year's end.
But those who hadn't responded within a month were never helped.
And diet and exercise alone helped three out of 10 patients lose as much weight.
Dexfenfluramine patients lost an average total of just 7.5 pounds more than dieters who didn't take the drug, Wolfe noted.
The drug should be used only under a doctor's close supervision because of the risk of primary pulmonary hypertension (PPH), a rare but sometimes fatal disorder that blocks the lungs' ability to get oxygen to the heart, the FDA said.
Some studies indicate people who take dexfenfluramine and similar drugs are nine times more likely to get PPH than the general public, but the disease strikes just one to two out of every million people, Bilstad said.
A bigger question has been brain damage.
When animals received 10 times the human dose, dexfenfluramine crippled their ability to make serotonin naturally.
Although there is no proof that people are similarly affected, 22 neurologists wrote the FDA in December to ask that it not allow dexfenfluramine for sale until the safety question is answered.
But the FDA concluded that Americans could take dexfenfluramine while its maker studies brain damage.
No studies in people, however, have signaled a problem so far, Bilstad said.
Dexfenfluramine will be sold by Wyeth-Ayerst Laboratories under the name Redux. It will hit pharmacy shelves this summer and cost about $2 per day.
Dexfenfluramine should be used by patients whose body-mass index - a calculation of height to weight - is at least 30, the FDA said.
Someone who is 5-feet-6 and weighs at least 186 pounds would qualify. However, dexfenfluramine may be used for people with a body-mass index as low as 27 - 5-feet-6 and 167 pounds - if the patient already has diabetes or another obesity-related illness, the FDA said.
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