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Qnexa’s Side Effect Profile has Critics Concerned

With the obesity epidemic on a collision course with no stop in sight, the FDA and drug developers are feeling the pressure to approve and develop weight loss drugs at a fast clip. Qnexa could be approved by the FDA by April but some people are wondering how this could happen when it was initially rejected by the FDA advisory committee a couple years ago.

Qnexa, which is a combination drug of phentermine and topiramate, was initially brought to the FDA advisory committee’s attention in 2010. The committee basically told the drug maker Vivus to go back to the drawing board and give them more concrete data about the phentermine portion of Qnexa would not lead to cardiac events like heart attacks even with its side effect of increased blood pressure. The committee also wanted a plan in place to prevent women of childbearing age from being exposed to topiramate’s birth defect potential if they became pregnant while on Qnexa.

When Vivus brought Qnexa back to the committee they found the slight rise in blood pressure had no effect on cardiac outcomes and they made Qnexa contraindicated, or not allowed to be prescribed in any woman of childbearing age. The advisory committee felt the restriction was too strict and asked instead for a precaution stating that woman of childbearing age should use caution with this medication and should stop taking it if they become pregnant. This leaves the physician in the driver’s seat as far as who are good candidates for Qnexa.

The fact remains that both of these drugs are already available individually and doctors do prescribe them for weight loss. I do have a suggestion for the makers of Qnexa that may help with the child-bearing age female demographic: why don’t we enforce mandatory monthly pregnancy tests before refills are allowed? I know it sounds a little extreme but this is exactly what is done with another medication that can cause major birth defects called isotretinoin or Accutane.

The program is called iPledge, not to be confused with anything from the Apple brand family. The patient has to have a negative pregnancy test result every month along with the physician and patient filling out patient counseling questionnaires that they understand the risks of taking and prescribing the medication. The patient must also agree to use two forms of contraception while taking the medication. As I’ve previously mentioned, topiramate or Topamax can interact with contraceptives like birth control pills, so another form of birth control, like a condom, should be used.

It’s the FDA’s job to protect consumers and make sure that drugs are vigorously tested before they go on the market. Even if Qnexa gets approved, if the FDA sees any trends with increases in cardiac events or birth defects and makes the connection that Qnexa is the culprit, you can kiss Qnexa goodbye.

March 5th, 2012

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(Page 1 of 1, 2 total comments)

Mark

Blood pressure isn't the issue here. The issue is that topiramate is a debilitating sedative that causes severe neuromuscular and cognitive impairment.

posted Mar 6th, 2012 4:41 am


Jared

what data do you have that states Qnexa increased blood pressure??? I dont have that information from any of their studies! In fact, every study I have shows a decrease in both systolic and diastolic blood pressure. I suspect you mean there was a small increase in heart rate.

posted Mar 6th, 2012 3:04 am



   
 

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