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Phentermine the Phoenix Rises Again


Oct 7, 2009

A combination of topiramate and phentermine fights weight gain on two fronts.

The demise of Fen-phen dealt a body blow to hopes for an obesity pill that is actually effective. Unfortunately, the fen in Fen-phen, fenfluramine, caused grave pulmonary hypertension and heart valve problems. The phen part of the drug, though, was apparently just an innocent bystander. And now phen (phentermine) has resurfaced in a new pill that has posted some amazing results in Phase III clinical trials. Patients who were treated for 56 weeks with the new drug, Qnexa, lost an average of 14.7 percent of their weight, or 37 pounds.

Qnexa, produced by Vivus, is a low dose formulation of immediate release phentermine combined with controlled release topiramate, otherwise known as Topomax. Topiramate, which was approved in 1996 for treating epilepsy, and more recently as a migraine preventer, increases satiety, or the sense of being full. Phentermine reduces appetite, and the combination of the two is apparently pretty potent.

Topiramate apparently increases satiety by enhancing the activity of GABA (gamma-aminobutyrate), a calming neurotransmitter that inhibits food intake.

Phentermine (pheny-tertiary-butylamine) is a sympathomimetic amine, which means that it produces effects similar to those caused by stimulating the sympathetic nervous system. By provoking the hypothalamus to release norepinephrine, a neurotransmitter that signals fight-or-flight, it reduces appetite, which is associated with the rest-and-digest response of the parasympathetic system.

The combination of a satiety increaser and an appetite reducer could be potent because, according to the New York Times, food consumption is a balance between a food-seeking  system, which says "eat," and a satiety system, which says ''stop eating.'' When either system is out of whack, weight control problems can result. The Chinese hamster, for example, which lives in the desert, completely lacks a satiety system. When it does manage to find some food, it keeps eating until the food is gone. Put that hamster in an environment with plenty of food, and you have one fat hamster.

Last month, Vivus announced the results of two year-long double-blind Phase III studies that evaluated the safety and effectiveness of Qnexa in more than 3,750 patients across 93 sites. The trials evaluated three doses of Qnexa: 15 milligrams of phentermine and 92 milligrams of topirimate; 7.5 milligrams of phentermine and 46 milligrams of topirimate, and 3.75 milligrams of phentermine and 23 milligrams of topirimate. The results demonstrated a favorable safety profile, improved glycemic control, and significant improvements in cardiovascular and metabolic risk factors. But the real kicker was the weight loss.

The average weight loss for patients who completed the first study was 37 pounds with full-dose Qnexa and 18 pounds with low-dose Qnexa, as compared to six pounds in the placebo group. Sixty percent of the full-dose patients who completed the study lost at least 10 percent of their baseline weight, and 43 percent lost at least 15 percent. The results of the second study were very similar.

There were no drug-related serious adverse events, and the most common side effects were tingling, dry mouth, altered taste and constipation.

An earlier Phase III clinical study showed that treatment with Qnexa not only lowered A1c's in diabetic patients, but also arrested the progression to diabetes by preventing increases in A1c in obese patients who were not yet diagnosed with type 2.

Vivus plans to file a New Drug Application with the FDA by the end of 2009. A New Drug Application, or NDA, is the means by which drug sponsors formally propose that the FDA approve their new pharmaceutical for sale and marketing.

* * *

Sources:

New York Times

Vivus press releases


Categories: A1c Test, Diabetes, Diabetes, Food, Medications Research, Pre-Diabetes, Type 2 Issues, Weight Loss



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Comments

Posted by Steve Parker, M.D. on 7 October 2009

I can't help thinking, "It's not nice to fool Mother Nature!"

-Steve

Posted by Anonymous on 14 October 2009

My doc absolutely refused to use Phentermine, I doubt he will prescribe this! But still, when the insulin makes you so darn hungry and you gain weight so easily...I'd like some more long-term health studies. :-)hope it goes well!

Posted by Pauline Barrett on 14 October 2009

I took the active ingredient topirimate, also called Topamax, for preventing migraine headaches for nearly two years. I did not lose any weight, though my headaches were reduced about 75%. However, my ability to recall my extensive vocabulary, play percussion in a concert band, or fully carry a thought in a conversation that was up to my standards (I'm a Mensan) really cut into my quality of life. After explaining this to my neurologist he changed me to Depakote that seems like a miracle drug. However it has side effects, too: weight gain for one.

To lose weight (as I have done) one has to eat less, remain active, and be positive.

Posted by Pauline Barrett on 14 October 2009

I omitted a very necessary word in my first posting....

I took the active ingredient topirimate, also called Topamax, for preventing migraine headaches for nearly two years. I did not lose any weight, though my headaches were reduced about 75%. However, my ability to recall my extensive vocabulary, play percussion in a concert band, or fully carry a thought in a conversation that was NOT up to my standards (I'm a Mensan) really cut into my quality of life. After explaining this to my neurologist he changed me to Depakote that seems like a miracle drug. However it has side effects, too: weight gain for one.

To lose weight (as I have done) one has to eat less, remain active, and be positive.

Posted by dorisjdickson on 14 October 2009

This "new" product contains Topamax. I have a herniated cervical disc for which I was taking Neuronton aka gabapentin as a nerve block but at night only because it made me sleepy. My neurologist suggested I try Topamax instead because it wasn't supposed to make you sleepy. Ironically, even though I was and have always been thin he commented "it even causes weight loss." OK but will it make me sick to my stomach. He ignored me. Well, I filled the script and proceeded to get violently ill taking it. I have never had a doctor apologize so vehemently for not listening to me. I was dizzy, sick to my stomach and unable to function for the duration of its half-life.

So ... sure, it might make people not hungry but it isn't the way I choose to lose my appetite!

Doris J. Dickson

Posted by Anonymous on 14 October 2009

I know I am lucky that I didn't suffer the bad side effects, but I had a wonderful experience with fen-phen. After I got used to the 'speed' effect, it was like a switch had been flipped and I didn't have the compulsive eating problem and food obsession I had before! It really worked well for three months and not as well for the next three, but well enough that my good eating habits became ingrained. I stopped taking the drugs then and concentrated on better food choices and exercising more.
I think the Phen is a good stepping stone and I hope it helps more people control their blood sugars and get to their healthy weight. It isn't something to be used forever, but a good boost.

Posted by Anonymous on 20 October 2009

My Phentermine expereince has been nothing but positive.

I'm a Type 2 Diabetic that had high blood pressure, high "bad cholesterol" and high triglycerides. I took Meridia for one month and it worked wonderfully in curbing my appetite, but after one month my insurance stopped covering it and I couldn't afford the full price. So my doctor prescribed Phentermine with strict instructions that if my heart started racing or I felt anything off to stop immediately and call her. She checked my blood pressure on a weekly basis for about three weeks.

Now 5 months later, my blood pressure is low-to-normal, my triglycerides are low, my "bad cholesterol" is excellent and most importantly I've lost 20 lbs.

Posted by shosty on 8 November 2009

Note to Doris: your dose was probably too large; if you ever want to try Topamax again, get the sprinkles (15mg) and take 1/3 at first, then 1/2, which could even be enough, and ramp up slowly as needed.


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