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Three New Weight Loss Drugs Up for FDA Approval


While obesity rates in the US continue to rise, pharmaceutical makers are creating new drugs that will help Americans finally lose weight. Three new drugs have finalized their clinical trials and are now awaiting FDA approval – Qnexa (Vivus Inc), Contrave (Orexigen Therapeutics), and lorcaserin (Arena Pharmaceuticals).

The FDA posted a review of Qnexa Monday and will hold a public meeting later this week to review the data. Contrave will be reviewed in October and lorcaserin in December. To be considered “effective”, obesity drugs should reduce total body weight by at least 5% after one year, according to the FDA guide to drug companies.

According to one recent report, none of the three medicines represents a breakthrough in research because drug makers have made little headway in understanding and treating the causes of overeating. Two of the drugs submitted for approval simply combine existing drugs, but have worrying side effects. The third, a new medication, is safer but less effective.

"We're using combinations of old drugs with a very broad spectrum of pharmacotherapy. It's very much the shotgun approach," said Jason Halford, a University of Liverpool professor and health psychologist who has consulted for drug companies on obesity treatments. He states that companies are trying multi-pronged approaches to obesity therapies because of the multiple brain signals that drive food intake.

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Qnexa has shown the best weight loss results in clinical trials. It is a combination of phentermine, an amphetamine which suppresses appetite, and topiramate, an anticonvulsant drug better known as Topamx which helps patients feel more satisfied. The FDA found that those taking the highest dose of Qnexa lost an average of 10.6% of their starting body weight.

Unfortunately, the drug also had the highest rate of patient dropouts due to side effects, which include memory and concentration problems. In the safety review of Qnexa, the FDA said that it found increases in heart rate among patients taking the drug and a number of patients who experienced heart palpitations, but the clinical significance of the finding is unknown. The agency also saw an increase in anxiety, sleep disturbances, and depression in patients taking Qnexa. Overall, the drug appears to be both safe and effective.

Contrave mixes an antidepressant (bupropion) with a drug that is normally used to treat alcohol and drug addiction (naltrexone). The drug has shown a weight loss between 5 and 10% with side effects such as nausea. The studies found that the drug is most effective when accompanied with lifestyle counseling.

Lorcaserin is a new drug that acts on serotonin, a brain chemical associated with feelings of well-being and satiation. There were few side effects, but unfortunately, patients only lost 5% of body weight.

Safety is the key issue in the FDA’s review of weight loss drugs. In the past, several anti-obesity medications have been discontinued due to severe side effects. Fenfluramine (half of fen-phen) was withdrawn in 1997 after it was linked with heart damage. Two years ago, Sanofi-Aventis SA discontinued studies of Acomplia due to psychiatric side effects, including depression and suicidal thoughts. Currently, Meridia and the over-the-counter weight loss pill alli are under scrutiny due to their link with heart and liver risks, respectively.