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Phentermine

Phentermine is a phenethylamine primary used as an appetite suppressant. It is typically prescribed for individuals who are at increased medical risk because of their weight, as opposed to cosmetic weight loss. more...

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Phentermine is sold either as an immediate-release formulation (Adipex®) or as a slow-release resin (Ionamin®, Australia:Duromine®).

History

Phentermine is one of two drugs in the Fen-phen anti-obesity medication, the other being fenfluramine or dexfenfluramine. Fenfluramine was withdrawn from the U.S. market in 1997 after reports of valvular heart disease and pulmonary hypertension.

Phentermine is still available by itself in most countries, including the U.S. However, because it is similar to the amphetamines, individuals may develop an addiction to it. Hence, it is classified as a controlled substance in many countries. Internationally, phentermine is a schedule IV drug under the Convention on Psychotropic Substances (PDF file). In the United States, it is classified as a Schedule IV controlled substance under the Controlled Substances Act.

Mechanism of action

Phentermine, as many other prescription drugs, works with neurotransmitters in the brain. It is a centrally-acting stimulant chemically related to the amphetamines. It stimulates neuron bundles to release a particular group of neurotransmitters known as catecholamines; these include dopamine, epinephrine (also known as adrenalin), and norepinephrine (noradrenaline). This is the same mechanism of action as other stimulant appetite suppresants such as sibutramine, diethylpropion, and dextroamphetamine.

The neurotransmitters signal a fight-or-flight response in the body which, in turn, puts a halt to the hunger signal. As a result, it causes a loss in appetite because the brain does not receive the hunger message.

Clinical use

Generally, it is recommended by the FDA that phentermine should be used short-term (usually interpreted as 'up to 12 weeks'), while following nonpharmacological approaches to weight loss such as healthy dieting and exercise. However, recommendations limiting its use for short-term treatment may be controversial. One reason given behind limiting its use to 12 weeks is drug tolerance, whereby phentermine loses its appetite-suppressing effects after the body adjusts to the drug. On the contrary, it has been shown that phentermine did not lose effectiveness in a 36-week trial (PMID 11054601). However, the risk of drug addiction may be a significant reason in limiting phentermine for short-term use.

Due to the risk of insomnia, it is generally recommended that the drug be taken either before breakfast or 1-2 hours after breakfast.

Side effects

Because phentermine acts through sympathomimetic pathways, the drug may increase blood pressure and heart rate. It may also cause palpitations, restlessness, and insomnia. Additionally, individuals taking this drug on a long-term basis may develop euphoria and a psychological addiction to it. Heart valve damage and pulmonary hypertension, severe enough to cause permanent disability or death have been seen with phentermine alone.

Read more at Wikipedia.org


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The fen-phen summer: weight loss brings unexpected results - weight-loss drugs fenfluramine-phentermine
From Communication World, 4/1/98 by Shelly Plutowski

Mayo Rochester Cardiologist Michael McGoon had called a few days earlier to let me know that he was going to send me a manuscript with the potential to attract a lot of media attention. It was a series of case reports that concluded there may be an association between taking the weight-loss drugs fenfluramine-phentermine (fen-phen) and developing valvular heart disease. Dr. McGoon's colleague, Dr. Heidi Connolly, was the primary author of the manuscript. It was scheduled to be published in the New England Journal of Medicine in several weeks, so we had some time to plan our communication effort.

While I waded through the 24-page paper, several facts leaped off the page.

* In 1996, physicians wrote more than 18 million prescriptions for a 30-day supply of fen-phen.

* Twenty-four patients with no known heart disease developed valvular problems after taking fen-phen.

* Five of the 24 required surgery to correct the problem.

As I read on, the paper described how a team of physicians, surgeons and allied-health staff from Mayo Clinic and MeritCare Medical Center in Fargo, N.D., had pieced together preliminary evidence linking fen-phen to heart disease:

A 41-year-old woman on fen-phen who underwent valve repair surgery at Mayo Clinic had a very unusual glistening white, thickened heart valve. The same woman later developed a second thickened valve with similar characteristics. Another young woman with previously normal heart function was found to have newly documented valvular problems after taking fen-phen. Twelve patients from North Dakota had the same unusual valve disorder - all had been on fen-phen.

Preparing for a Public Response

Unusual event + many people + significant impact = big news, my PR brain calculated. But my initial equation didn't factor in several events that would take place over the next weeks and months that would make this case series even more significant.

First, a New England Journal of Medicine editor called Dr. Connolly with a rare request that was a strong departure from normal journal policy: Would Mayo be willing to make a statement prior to the publication of the report? Perhaps within the next few days? The journal's editorial board had decided the material in the article had public health implications and needed to be reported early.

After careful consideration, Dr. Connolly and the team of authors - Drs. McGoon, Donald Hensrud, Brooks Edwards, William Edwards, Hartzell Schaff and Jack Crary of MeritCare - agreed. But communicating the study results without a formal scientific publication created a new set of challenges for us.

How could we reach physicians with these findings so they could be prepared for patients' questions? How could we get in touch with the proper people at key governmental agencies such as the U.S. Food and Drug Administration (FDA)? How could we provide accurate information and recommendations to concerned patients who were taking these medicines and would look to us for answers?

We found the answers in another act of Mayo teamwork. Representatives from Video Communications, Mayo's health information web site (www.mayohealth.org), Mayo's institutional web site (www.mayo.edu), Visual Information, Patient Education, Communications, Administration, Nursing and Cardiovascular Diseases gathered to strategize and implement a plan that included the following:

* Work with the FDA to use their existing procedures and vehicles for communicating with physicians before any formal media announcement.

* Use the Internet/intranet and electronic media to quickly communicate our findings to staff and the lay public.

* Hold a live news conference via satellite to communicate consistent messages to major media.

* Develop a mechanism to handle e-mail and telephone inquiries from patients with the goal of quelling panic and emphasizing that the findings are preliminary.

Executing the Plan

Tuesday, July 8, was D-day. Our carefully prepared plans were executed, and the response was astounding. That day, we received hundreds of calls from news media throughout the United States and the world, resulting in articles and broadcasts that reached an estimated 200 million people.

On the day after the announcement, more than 6,000 visitors logged on to our external web site, which contained the unedited manuscript and other information for both physicians and patients.

Mayo Health Oasis, an Internet information resource operated by Mayo Medical Ventures, posted several articles about the fen-phen findings and other weight-management issues. Traffic to that site also was at an all-time high.

But the most telling reaction to our statement was - and is - the flood of phone calls and e-mail we've received from frightened patients. Sue Tointon, the cardiovascular nurse designated to respond to the calls, received more than 350 inquiries in the days following the July announcement. That has grown to nearly 1,000 to date.

It's odd. Looking back on the summer that I spent "fen-phening," it isn't the media hoopla and logistical details that I think of. It's the people that our announcement affected, such as the woman who wrote the following in an e-mail note:

"Thank you so much for all that you're doing in the field of medicine."

Of course she wasn't thanking me personally - I had nothing to do with the science of the study. But I do believe that she was expressing appreciation to the collective us who form the face of Mayo Clinic. Because - as I discovered this July - it is truly through all of our efforts that we fulfill our mission of healing the sick and advancing the science.

The Fall of Fen-phen

July 8 - Mayo announces a potential association between fen-phen and valvular heart disease.

Aug. 28 - New England Journal of Medicine publishes Mayo/MeritCare study. A journal editorial calls for a moratorium on the use of diet drugs for cosmetic weight loss.

Since Mayo's July 8 announcement, 58 more cases of heartvalve damage in patients on fen-phen have been reported to the FDA, including seven patients taking only dexfenfluramine (Redux) and two taking only fenfluramine. The agency calls for new drug labels warning patients of potential danger.

Mayo and Wyeth-Ayerst announce plans to coordinate a new, multi-center fen-phen study.

Sept. 8 - The state of Florida issues a temporary ban against fen-phen until it can develop specific rules for its use.

Sept. 15 - The manufacturers of fenfluramine and dexfenfluramine withdraw the drugs from the market at the request of the FDA after new information indicates that they might cause valve damage in as many as 30 percent of users.

Shelly Plutowski is a member of Mayo Clinic's division of communications, Rochester, Minn.

COPYRIGHT 1998 International Association of Business Communicators
COPYRIGHT 2004 Gale Group

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