March 22 (UPI) -- An affordable weight-loss drug that hit the market 60 years ago for short-term use may now also help over an extended period of time, a new study says.
Researchers say that phentermine is a safe, effective drug for long-term weight loss, according to research published Friday in the journal Obesity. And they say the longer a person stays on the drug, the more weight they can lose. Long-term use was not associated with a spike in blood pressure or elevated risk of heart attack or stroke.
"Although diet and exercise are critical components of any weight-loss program, up to half of patients don't have long-term success with lifestyle changes alone," said Kristina H. Lewis, a researcher at Wake Forest Baptist Health and study first author, in a news release.
According to the researchers, phentermine is FDA-approved for up to three months.
"In those cases, medications or surgery can help. Generic phentermine is an effective and affordable option, but now that we view obesity as a chronic disease, it's important to have medications that can be used indefinitely. Most new weight-loss drugs are approved for long-term use, but unfortunately the newer drugs can be expensive if they are not covered by insurance," Lewis said.
The researchers compared health records for nearly 14,000 adults who received phentermine prescriptions: those patients who used it short term and those who took it for long-term use. They examined weight changes and blood pressure for up to two years, as well as risk of stroke, heart attack or death for as many as three years, based on the length of time a patient used the drug.
The researchers warn that people with heart disease, stroke or uncontrolled high blood pressure should not use phentermine, although it could be a good option for people with high blood pressure and low cardiac risk.
In the mid-90s, the combination drug of phentermine and fenfluramine, commonly referred to as Fen-Phen, became a popular weight-loss solution for millions in the U.S. The drug was banned, however, by the Food and Drug Administration after many dieters reported heart valve damage.
Nearly 40 percent of all Americans are obese, according to the Centers for Disease Control and Prevention.
"For patients who respond to and tolerate it, phentermine may be a safe and affordable way to achieve greater and longer lasting weight loss, but we need clinical trials to provide more certainty," Lewis said. "At the moment, there is no change to the FDA labeling so doctors should use caution with the decision about prescribing it longer-term."