To address those worries, Qnexa’s maker, Vivus Inc., had suggested approval of drug only for use in men and in women of non-childbearing age. That type of labeling work-around didn’t satisfy the FDA, however, and the agency asked the company to figure out a way to prevent pregnant women from using it.
Qnexa is not the first, nor will it be the last weight-loss pill to seek approval from the FDA. The market is ripe for a new drug to help Americans lose weight: “We really go from Weight Watchers to bariatric surgery when it comes to treatment options,” said Joseph Nadglowski, president of the Obesity Action Coalition, a patient advocacy group in Tampa, Fla., in an interview with Bloomberg. “For many, that’s a pretty big gap.”
But the FDA has a spotty history with diet drugs and an ever-rising bar for new weight-loss remedies. Following is a brief history of the diet drug industry’s successes, failures and near misses.
The original diet drugs date back to the 1950s. Amphetamines worked simply by boosting metabolism all around, driving the body to burn more calories faster. The problem — as with any energy system pushed to its limits — was that cells aren’t made to burn, burn, burn. They eventually burn out, leading to heart problems, chest pains, palpitations, insomnia and other health issues.
Amphetamines, which boost energy and mood, are also addictive, since they tap into the brain’s reward system. After their potential for misuse emerged, U.S. and European officials banned most amphetamine-based medications, but the drug is still available, often hidden in South American diet remedies.
Fen-phen and Redux
A new combination of the existing appetite-suppressing drugs fenfluramine and phentermine, fen-phen was all the rage in the mid-1990s, leading to weight loss in hundreds of thousands of Americans. In 1996, after much media attention, the FDA approved a related drug, dexfenfluramine, as Redux, which did the same thing as fen-phen but with fewer side effects. Yet the side effects were still severe: in the summer of 1997, the FDA revealed that 82 patients had developed defects in their heart valves while on fen-phen, and that seven patients had come down with the same condition on Redux. Other patients developed pulmonary hypertension, a sometimes fatal lung condition, and a JAMA study confirmed earlier reports that both fen-phen and Redux caused brain damage in lab animals. After millions of prescriptions written, in 1997 both fenfluramine and Redux were pulled from the market.
Since amphetamines carried too many risks of addiction and other side effects, researchers began focusing on ways to trick the brain into wanting less food. Sibutramine, approved in 1997, worked on brain chemicals that affect appetite: by blocking the reuptake of neurotransmitters such as norepinephrine and serotonin, the drug could suppress the desire to eat and convince the body that it was full, helping dieters lose 5% to 10% of their body weight in a few months. After studies showed users were at higher risk of developing heart problems and stroke, however, the medication was withdrawn from the market in 2010.
Like sibutramine, lorcaserin focused on altering brain chemicals, specifically serotonin, to convince the body it was full. But an FDA panel recommended in 2010 against approving the drug because of studies in which female rats taking the drug developed a disturbing number of mammary tumors. The panel also asked Lorqess’s maker, Arena, to conduct additional tests on the drug’s effect on users with diabetes and heart disease, conditions that commonly affect those who are overweight.