162 Fenfluramine
monary hypertension and edema among users living or traveling in high al-
titudes. Phentermine is a monoamine oxidase inhibitor, and despite a lack of
reports about acute adverse interaction with fenfluramine, some researchers
noted that a more chronic interaction could cause the kind of heart and pul-
monary damage that was appearing. Researchers began reporting organic
brain damage from fenfluramine and dexfenfluramine in animal experiments.
Investigators now noticed many instances of psychiatric disturbance among
persons taking fenfluramine and noted that the disorders implied organic
brain damage. The drug was also linked to human angina pectoris (a fright-
ening sensation of pain and suffocation typically caused by insufficient oxygen
supply to the heart) and to a case of a gangrenous condition resulting in
amputation of fingers. As time passed, evidence appeared that the heart valve
and pulmonary hypertension disorders could stabilize and even improve after
patients stopped taking fen-phen. Scientific debate continues about fenflura-
mine’s role in heart ailments and pulmonary hypertension.
Despite the beating that fen-phen took from the news media and from many
scientists, researchers remain curious about whether the drug combination still
has a role in medicine. Even though fenfluramine can cause depression, in-
terest arose in possible psychotherapeutic uses. As the twenty-first century
began, experimenters reported that fen-phen can ease withdrawal fromco-
caine. Rat experiments find that fen-phen reducesalcoholintake and elimi-
nates alcohol withdrawal symptoms, findings that may be relevant to
treatment of alcoholism. Indeed in 1995 one medical practitioner reported suc-
cess in treating alcohol and cocaine addicts with fen-phen, sometimes substi-
tutingpemolinefor phentermine.
Cancer.Not enough scientific information to report.
Pregnancy.Experimenters who gave fenfluramine to pregnant mice found
no measurable effect on fetal development and no effect on offspring’s ability
to perform in learning tests. For primates evidence exists that the drug passes
into the fetus and reaches high levels there. The combination fen-phen has not
seemed to harm human fetal development.
Additional information.Dexfenfluramine (CAS RN 3239-44-9) is a stereoi-
somer of fenfluramine, meaning the two molecules have the same chemical
formula and the same atomic bonds, but the molecules look different (as a
person’s left and right hands look different even though both have the same
components). Studies comparing the two drugs find little or no difference in
effect, although dexfenfluramine was introduced with the hope that it had
fewer unwanted actions than fenfluramine when used for weight loss. A re-
port praising dexfenfluramine characterized its weight loss capability as equal-
ing that produced by the antidepressant fluoxetine (Prozac) or by a
combination ofephedrineandcaffeine. Diarrhea is noted as a dexfenflura-
mine effect, and concern arose that the drug can aggravate glaucoma. De-
pending on laboratory manipulations of circumstances, it can promote or
diminish panic attacks.
Additional scientific information may be found in:Davis, R., and D. Faulds. “Dexfenfluramine. An Updated Review of Its Therapeutic
Use in the Management of Obesity.”Drugs52 (1996): 696–724.