It has been 13 years since the last weight loss drug was approved by the FDA. This summer, we have two.
To date, not many weight loss drugs have been made available by prescription. Phentermine has been on the market since 1959. Although most of you would better remember when it was combined with Wyeth’s fenfluramine in the 1990’s to become the much sought after fen-phen. The drug was pulled in the late ’90’s after it was discovered that fenfluramine could cause fatal heart valve damage. While phentermine is still available singularly, and is now a component of the newly approved Qsymia, it does not come without its’ own potential side effects, like increased blood pressure.
Then we had Roche’s Orlistat (AKA Xenical), which ultimately became available over the counter by GlaxoSmithKline as Alli. This drug works by inhibiting fat digesting pancreatic enzymes, which in turn blocks fat absorption from the gastrointestinal tract. As far as Alli’s side effects, let’s just say that eating a high fat meal without being in close proximity to a rest room could be disastrous!
Vivus’ Qsymia is a once-a-day pill combining two previously FDA approved drugs, phentermine and topiramate. Topiramate was originally approved in 1996 as an anticonvulsant/antiepilepsy drug, and has a lofty list of potential side effects including paresthesia (numbness and tingling), upper respiratory tract infection, memory problems, and anorexia (hence, the weight loss). The recommended daily dose is 7.5 mg phentermine and 46 mg topiramate, but there is a higher dose available which combines 15 mg of phentermine and 92 mg of topiramate for “select” patients, per the FDA.
Two placebo-controlled trials were conducted using the highest dose available, and treated 3700 obese or overweight participants for one year. Weight loss for the two studies averaged 6.7% and 8.9%, respectively, over treatment with placebo. Participants treated with the drug who did not lose 3% of their body weight within 12 weeks were not likely to have further success continuing in the trial, so it looks like some people just did not respond well at all. Whether or not this drug increases risk for cardiac events is not known at this time, as Vivus will be conducting trials while the drug is already on the market.
Belviq works by increasing serotonin. In three randomized placebo controlled trials, 8,000 overweight or obese participants (some with type 2 diabetes) were treated from 52-104 weeks. Weight loss with Belviq after one year averaged from 3% – 3.7%, and overall, better glycemic control was found in the type 2 diabetic participants. The most common side effects were headache, dizziness, fatigue, nausea, dry mouth, and constipation. Six studies are in progress to assess cardiac event risk.
Both Qsymia and Belviq are meant to be taken as an adjunct to healthy lifestyle changes, including a low calorie diet and regular exercise. These drugs are only recommended for adults who are obese (BMI >30) or overweight (BMI >27) with at least one weight related disease such as high blood pressure or type 2 diabetes, and are meant for lifelong use, unless side effects develop that would prevent the individual from taking the drug safely.
If you are considering Qsymia or Belviq, discuss your options thoroughly with your doctor, and proceed with caution. These drugs are new, and while they may have their place for some individuals, they are not a magic bullet, and do not have an endpoint. Doctors prescribing diet drugs may now have a few more tools in their chest, but there is still no substitute for plain old healthful eating and exercise.
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