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Qnexa, Contrave, and Lorcaserin - Three New Diet Pills seeking FDA approval

Updated on January 29, 2014
Photo courtesy of
Photo courtesy of


I found out about these three new potential diet pills Qnexa, Lorcaserin and Contrave when I was carrying out the research for my hub Hemopressin - A natural way to curb appetite? These three drugs are currently seeking FDA approval this year and it is causing something of a stir.

So why the stir?

You might well be asking why this is as we all know that FDA approval is needed before any drug can be marketed. Well the reason is two-fold. Firstly these three drugs are the first diet pills to seek FDA approval in a decade and secondly if approved these drugs stand to make millions of US dollars for the companies and their shareholders. The market for the treatment of obesity is huge and pharmaceutical companies from around the globe are all seeking the alchemy formula that will turn the base chemicals into gold! One estimate I’ve seen puts the global diet pill market at over $10 billion(US) by 2018. The News Update Video to the side provides details of a deal struck by one of the developers of the three drugs and the sums involved are not insignificant.

Photo courtesy of Janine on Flickr
Photo courtesy of Janine on Flickr

California Connection


What is also surprising is that the three companies each seeking approval for their drug Vivus Inc (Qnexa), Orexigen Therapeutics Inc (Contrave) and Arena Pharmaceuticals Inc (Lorcaserin) are all US companies and they are all based in California.  Vivus is based in Mountain View and Orexigen and Arena are both based in San Diego and none are what you would consider to be amongst the bigger players in the industry.

So what exactly will the FDA do

 The FDA will make a balanced judgement on the suitability of each drug in a number of key areas.

  1. Is the drug effective and safe?  They will weigh the drugs ability in providing weight loss against the side effects it may produce.

  2. Are the methods that will be used in manufacturing the drug and the controls that will be in place sufficient to ensure the drug's strength, quality, and purity?

  3. Is the drug's proposed labeling appropriate, and does it contain the necessary information?


Side Effects

We have all heard about the side effects of drugs and those readers, who are old enough to remember the horrendous problems of the diet pill Phen-Fen, will know that diet drugs can produce very serious side effects. Phen-Fen was taken off the market in October 1997 because of the serious and sometimes fatal damage it caused to heart values.

Whilst I would not expect any sympathy for the companies involved the side effects can cause serious financial damage to the pharmaceutical company. Wyeth has advised that it has set aside $21.1 billion (US) to cover the cost of the lawsuits arising from the damages caused by Phen-Fen.


Qnexa is a once-a-day, orally taken drug which provides a controlled release of two existing approved drugs phentermine and topiramate. Phentermine is a widely prescribed appetite surpressant and was the Phen in Phen-Fen and topiramite is an anticonvulsant drug. The combination of these two drugs in low doses to reduce the severity of the side effects has produced some very impressive weight loss in patients on the trial. Those who took Qnexa lost almost 9% more weight than those taking the placebo sugar pill so it comfortably meets the 5% measure that the FDA recommends for medical weight loss products.  The news video to the side gives details of two successful patients losing weight using Xnexa.

High doses of topiramate are known to cause birth defects in animals and those patients in the trial who were taking high doses of Qnexa reported three times as much anxiety and depression as the control group and also reported problems with memory, concentration and speech. Qnexa also appears to increase heart rate.


Like Qnexa Contrave is a combination of two existing approved drugs. Naltrexone which is used to treat addictions and Bupropion which is used to treat depression. In the trials Contrave also easily met the FDA 5% measure with patients typically losing between 9% and 15% of their body weight.

So far the only side effects I’ve seen reported are for nausea, headaches and constipation so the side effects do seem to be less serious than those for Qnexa.


Lorcaserin is a totally new drug but it has a similar chemical make up to Fenfluramine, the notorious Fen in Phen-fen. However in trials no heart value problems have been reported and it appears that of the three drugs it is the one with the least side effects. It is unfortunately ist is the least effective at producing weight loss although it does still meet that FDA 5% measure.

The side effects reported are headaches, nausea, dizziness, fatigue and a driness in the mouth and as it does not provide a feeling of elation it has a lower probability of producing addiction and abuse.


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    • Amber Allen profile image

      Amber Allen 7 years ago

      Hi Pamela

      Thanks for commenting on my hub. Unfortunately all drugs have side effects to one degree or another.


    • Pamela99 profile image

      Pamela Oglesby 7 years ago from United States

      Amber, This is an interesting article as I heard this drug mentioned on TV and was wondering if it had side effects like so many do. Good article.