Fenfluramine 161that purpose. One study found it comparable todextroamphetaminein pro-
ducing weight loss.
Drawbacks.Fenfluramine tends to dry out the mouth, a condition promot-
ing tooth decay. Other unwanted actions can include headache, peevish feel-
ings, dizziness, tiredness, nausea, vomiting, diarrhea, and frequent urination.
Experience indicates that persons need to be weaned off the drug; cold turkey
cessation can cause depression or even a medical emergency called “serotonin
syndrome.” That syndrome may include hyperactivity, confusion, nervous-
ness, vomiting, too-rapid heartbeat, excessive body temperature, shivering,
tremors, weakness, or passing out.
Abuse factors.Experimental animals have shown little interest in receiving
fenfluramine doses, a classic sign of small addiction potential. Human am-
phetamine addicts have found fenfluramine to feel like a placebo.
Drug interactions.If the compound is taken along with migraine headache
remedies or antidepressants (particularly monoamine oxidase inhibitors—
MAOIs) serotonin syndrome can arise.
Researchers discovered that fenfluramine could be administered in combi-
nation withphentermine, an anorectic that works in a different way. The
combination became known as fen-phen (or phen-fen). Rat experiments
showed that fen-phen reduces food intake far more than either drug can do
alone, and experience confirmed the same kind of multiplier effect in humans.
Such impact allows persons to take lower doses than would be necessary with
either drug alone, thereby minimizing any undesired actions of the drugs.
Phentermine counteracts fenfluramine’s common sedative quality, allowing
users to function more normally.
Weight control is one of the most challenging conditions encountered by
medical practitioners, and fen-phen became tremendously popular. One study
found that almost 90% of 88 obesity patients taking fenfluramine or the closely
related drug dexfenfluramine were also taking phentermine and that almost
33% of the 88 patients lacked obesity levels for which these or other anti-
obesity drugs were an appropriate treatment.
Suddenly, after many years of wide use without much report of alarming
adverse effects, in 1997 accounts began associating fenfluramine with rapidly
developing fatal heart valve disorders. The U.S. Food and Drug Administra-
tion asked the manufacturer to withdraw fenfluramine and dexfenfluramine
from the market. In that litigious era the manufacturer instantly and volun-
tarily complied. Hot debate then erupted in medical circles about whether
heart disease was caused by fenfluramine, phentermine, or the two drugs in
combination. Studies purported to confirm that the drugs alone or in combi-
nation really did create heart valve affliction. Other research purported to find
no evidence of the drugs’ involvement. Highly knowledgeable and distin-
guished medical authorities took differing stances on the question and raged
at one another in scientific journals. An issue also arose of whether fen-phen
caused fatal pulmonary hypertension (high pressure in blood circulation to
lungs), with researchers reminding fellow scientists that fenfluramine works
in ways similar to the anorectic drug aminorex, which had been linked to
pulmonary hypertension in the 1960s and was thereafter withdrawn from the
market. Particular concern was expressed about fenfluramine’s impact on pul-