History Phentermine is the most commonly prescribed prescription appetite suppressant,
accounting for 50% of the prescriptions. Part of this reason is because it's
significantly cheaper than the other major FDA-approved diet drugs, Meridia and
Xenical.
Phentermine first received approval from the Food and Drug Administration (FDA)
in 1959 as an appetite suppressant for the short-term treatment of obesity.
Phentermine resin became available in the United States in 1959 and
Phentermine Hydrochloride in the early 1970s.
In the US, Phentermine is currently sold under the brand names Ionamin®
(Medeva Pharmaceuticals) and Adipex-P® (Gate Pharmaceuticals). It is also
available as a generic medication, known as 'phentermine'.
Previously, it was sold under the name Fastin® (formerly produced by King
Pharmaceuticals for SmithKline Beecham). In December 1998, SK-Beecham withdrew
Fastin from the market.
As Phentermine is an older drug, no new efficacy trials have been conducted.
The one notable exception, are several trials on the combination of Phentermine
and Fenfluramine in the early and mid 1990s.
Fen-Phen (or Phen-Fen) and Dexfen-Phen - two passing trends
Fen-Phen refers to the combination, or cocktail, of Fenfluramine or Pondimin
(the "Fen") and Phentermine (the "Phen"). Fenfluramine received FDA approval in
1973 for the short-term treatment of obesity. Together, Phentermine and
Fenfluramine produced a powerful diet drug cocktail.
The FDA never approved the Fen-Phen combination, but once the agency has
approved a drug, doctors may prescribe it at will. Their use, together, was
considered "off-label".
In 1992, Dr. Michael Weintraub of the University of Rochester and several
colleagues published a study citing Fen-Phen as a more effective method than
dieting or exercise in reducing the weight of the chronically obese. Even
better - Fen-Phen, unlike an earlier generation of speed-laden diet drugs,
seemed to be without immediate side effects.
The Fen-Phen cocktail became an overnight sensation. 1996 saw 6.6 million
prescriptions of Fen-Phen in the U.S.
Dexfen-Phen refers to the combination, or cocktail, of Dexfenfluramine or
Redux (the "Dexfen") and Phentermine (the "Phen"). Dexfenfluramine received
FDA approved in 1996 for use as an appetite suppressant in the management of
obesity.
Like Fen-Phen, Dexfen-Phen, too, became an overnight sensation.
Neither combination, however, was ever tested for safety ....
By the summer of 1997, the Mayo Clinic reported 24 cases of heart valve
disease. All 24 people had taken the Fen-Phen cocktail. The cluster of unusual
cases of heart valve disease in Fen-Phen users suggested a co-relation between
Fen-Phen use and heart valve disease.
On July 8, 1997 the FDA issued a Public Health Advisory to report the Mayo
findings (which were later published in the August 28 issue of the New England
Journal of Medicine). Please click here to read the FDA Health Advisory.
The FDA continued to received additional reports of heart disease, including
reports from patients who had taken only Fenfluramine or Dexfenfluramine.
Further evaluations of patients taking Fenfluramine or Dexfenfluramine, showed
that approximately 30% had abnormal valve findings. This figure is much higher
than expected for abnormal test results and suggest Fenfluramine and
Dexfenfluramine as the likely causes of Primary Pulmonary Hypertension (PPH) and
valvular heart disease.
The FDA responded promptly to the alarming findings, and in September 1997,
requested drug manufacturers to voluntarily withdraw Fenfluramine and
Dexfenfluramine. At the same time, the FDA recommended that patients using
either Fenfluramine or Dexfenfluramine stop taking them. To view the FDA
September 1997 statement regarding the withdrawals, please click here.
The FDA did not, however, request the withdrawal of the third drug involved in
the cocktails, Phentermine.
Phen-Pro
The newest cocktail involving Phentermine is "Phen-Pro" - the "Pro" standing for
Prozac. Any one of the following antidepressants: Zoloft, Celexa, Luvox,
Trazadone or Effexor may be used in lieu of Prozac.
The use of the antidepressant in the Phen-Pro cocktail is unrelated to depression.
The cocktail is necessary because the effects of Phentermine, when used alone,
lessen over time. The Phen-Pro cocktail enables Phentermine to work better and
for a longer period of time. The cocktail does not appear to cause the problems
that resulted from the usage of Fen-Phen.
The combination of Phentermine and Prozac is considered an "off-label" use,
meaning that the FDA, who often voice concerns regarding the mixing/combining
of medications, does not approve it. However, once the agency has approved a
drug, doctors may prescribe it at will.
For further information on Phen-Pro, we suggest the
following article from
the American Medical Association (AMA).
Phentermine is the most commonly prescribed prescription appetite suppressant, accounting for 50% of the prescriptions. Part of this reason is because it's significantly cheaper than the other major FDA-approved diet drugs, Meridia and Xenical.
