Health and Human Services.Federal Register. 68, no.
133 (July 11, 2003). [cited May 7, 2007].http://
[http://www.cfsan.fda.gov/acrobat/fr03711a.pdf.](http://www.cfsan.fda.gov/acrobat/fr03711a.pdf>.)
Higdon, Jane. ‘‘Essential Fatty Acids.’’Micronutrient Infor-
mation Center. Linus Pauling Institute, Oregon State
University. December 7, 2005. [cited May 7, 2007].
http://lpi.oregonstate.edu/infocenter/othernuts/
omega3fa/.
Larsen, Joanne. ‘‘Fatty Acids’’.Ask the Dietitian. [cited May
7, 2007].http://www.dietitian.com/fattyaci.html.
Deborah Lycett, BSc(Hons) RD MBDAFeingold dietseeDr. Feingold diet
Fen-Phen
Definition
Fen-Phen was an anti-obesity regimen composed
of fenfluramine or the closely related drug dexfenflur-
amine (marketed under the brand name Redux) and
phentermine (sold under several brand names includ-
ing Adipex-P, Anoxine-AM, Fastin, Ionamin. Obe-
phen, Obermine, Obestin-30 and Phentrol). The
combination was found to cause damage to heart
valves, and fenfluramine and dexfenfluramine were
removed from the United States market in 1997.
Purpose
The combination of these two drugs had been
reported to be significantly more effective than pla-
cebo in promoting weight loss when used in combina-
tion with diet, exercise and behavior modification.
Description
Phentermine was first approved for use by the
United States Food & Drug Administration (FDA) in
- It’s claimed advantage over other appetite sup-
pressants available at the time was a reduced risk of
abuse. While the drug was chemically related to the
amphetamines, with the same side effects, the inci-
dence of these side effects was reportedly lower than
with the amphetamines.
Fenfluramine was approved by the FDA in 1973
and dexfenfluramine (Redux) was approved for use in
- Fenfluramine is the racemic form of dexfenflur-
amine. The drugs were approved for short term use as
part of a program of diet and exercise. Although fen-
fluramine is chemically related to the amphetamines,
its action appears to be based on increasing levels of
serotoninin the brain and blood stream. Ddexfenflur-
amine had been marketed in Europe for over a decade
without detection of an association between dexfen-
fluramine and heart valve problems, however the
FDA noted that the number of patients having heart
valve problems was very low compared to the total
number of patients using the drug, and heart valve
screening is not a routine part of drug monitoring.
Neither fenfluramine nor phentermine had been
approved for use in long term treatment or combina-
tion therapy. The drugs were indicated only as short
term adjuncts in patients withobesity.
In 1992, a research group from the University of
Rochester published reports indicating that the combi-
nation of fenfluramine and phentermine might be a
valuable adjunct to diet and exercise in a controlled
program of weight loss. A total of 121 patients were
initially enrolled in the study, and 9 dropped out during
the active study period. After the first 34 weeks of the
study, patients on the fen-phen regimen had lost an
average of 14.2 Kg, compared with a 4.9 Kg. weight
loss in the placebo control group. The researchers noted
that upon discontinuation of the drugs, patients
regained most of the weight lost during the study, and
after 210 weeks, the agerage weight loss was only 1.4 Kg
below the baseline. Patients who had received active
drug tended to regain weight more rapidly than those
who received placebo. The authors concluded that
despite long periods of time at weights much lower
than baseline, permanent resetting of weight control
mechanisms could not be shown for most participants.
In spite of the disappointing long term results,
these reports lead to the wide use of the fen-phen
regimen for people attempting to lose weight. InPhen-fen pills in a nonprescription herbal form.(Leonard
Lessin/Photo Researchers, Inc. Reproduced by permission.)Fen-Phen