Qsymia is Not Fen-Phen

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If there is one medical area where drug development has been hampered by extreme caution, it is obesity. Despite the "epidemic" of obesity and its associated type II diabetes we hear so much about, new weight loss candidates have been handled by pharmaceutical companies and the FDA as if they were Kryptonite.

This is clearly due to the fallout from the fen-phen debacle of 1997, when Wyeth was forced to withdraw the two-drug combination pill called Redux because of serious side effects heart valve damage and, in rare cases, a fatal lung condition called primary pulmonary hypertension. In addition to the people who suffered or died from these side effects, the withdrawal of Redux was a major blow to patients struggling to control their weight, since it was pretty much the only effective weight loss drug available at that time. Even after the withdrawal was announced, some people desperately tried to buy the remaining inventory, since it was the only drug that ever worked for them.

The unfortunate legacy of Redux was a visceral association between diet drugs in general and heart problems. This resulted in extreme caution in the field, and is a major factor behind the 13-year interval between the withdrawal of Redux and the recent approval of two new weight loss drugs, Belviq (lorcaserin) and Qsymia (formerly called Qnexa).

Although the two new drugs both have frightening warning labels, there is no scientific reason to expect that either should have the same side effect profile or risks associated with Redux. This is due to differences in the chemical structures between both drugs.

Fen-phen was an abbreviation for fenfluramine, a stimulant and phentermine, an appetite suppressant, which has been used for more than forty years. All of the adverse effects of Redux were attributed to the "fen" component. And it wasn't actually the fenfluramine itself that was the problem-- it was the major metabolite, norfenfluramine, which is formed by breakdown of the parent drug in the liver.

Norfenfluramine then binds to a subtype of serotonin receptors in the heart, causing an over-proliferation of cells in cardiac valves which leads to fibrosis and subsequent valve damage. Phentermine cannot form norfenfluramine and has not been implicated in the cardiotoxicity from Redux.

Therefore, Qsymia, which contains phentermine and another drug, topimerate (an anti-seizure medication), in place of fenfluramine should be no more likely to cause heart damage than any other new drug.

Yet this did not stop the anti-drug group Public Citizen, formed in 1971 by Ralph Nader, from using their now-familiar scare tactics.

Spokesman and perennial drug-hater Dr. Sidney Wolfe declared it to be "magical and delusional thinking for anyone to believe that a drug will turn off hunger without hitting other targets where it will do harm, usually to the cardiovascular system."

Well, I may be delusional, but I disagree. There is no reason that an appetite suppressant should necessarily cause cardiac toxicity. The problems caused by Redux were caused by a specific metabolism of the fenfluramine component--not the fact that it happened to affect one's appetite. The linking of these two phenomena is scientifically illogical.

As with any drug, Qsymia will have side effects in some people. But to focus simply on the risk without considering its benefit is the typical scare-mongering technique of anti-pharmaceutical activists.

Obesity is a serious problem, with its own long list of serious health effects. To dismiss any new pharmacological therapy because of problems with past drugs is foolish and does a disservice to the millions of people in this country who are struggling with serious weight problems.

Qsymia is Not Fen-Phen (Medical Progress Today)