Question from: 7/28/97

by Kevin M. Holthaus, M.D.
(on left)

Answer: Redux, Fen-Phen, And Your Heart

I've been listening to all the news studies about Fen-Phen and wondered if Redux was in this same class ?

Redux (D-fenfluramine, Dexfenfluramine) and Pondimin (fenfluramine, D,L,-fenfluramine, "Fen") are very similar in structure and function. They work by increasing levels of a substance called serotonin in the central nervous system. Elevated levels of serotonin mimic a recent feeding, decreasing your urge to eat. Used alone without a well designed diet and behavior modification they are not terribly effective for successful long term weight reduction. The best results are obtained when the medication is given in a controlled fashion by physicians knowledgeable in its use and in the context of behavior modification, education, and continual reinforcement.

Dexfenfluramine (Redux, D-fenfluramine) comprises 50% of fenfluramine. The other 50% is L-fenfluramine, the optical isomer of D-fenfluramine. Optical isomers are compounds that may have the same sequence or chemical composition as each other, but the three dimensional relationship is opposite. If you look at yourself in the mirror and raise your RIGHT hand, the image in the mirror looks identical to you, but the figure in the mirror technically has their LEFT hand raised. Optical isomers are mirror images of each other. In three dimensions this would be akin to two mirror image keys; they look the same but only one will fit the lock mechanism, and so it is with molecules and receptor sites in the brain. Confusing isn't it?

Recently, There have been reports of possible injury to heart valves by either the combination of "Fen-Phen" or Redux. The changes in heart valves is similar to changes noted when the material in heart valves is "soaked" in serotonin or the "ergot" medications (chemically similar to serotonin) used for migraine headaches.

The information right now is very preliminary and has not been corroborated by outside sources. Given that there are reports of problems in 34 patients with heart valve problems or pulmonary hypertension out of an estimated 3 million people who have used the medication, the level of alarm in the press MAY be premature.

Being more than 30% overweight may be more risky than the medications, if used prudently.

My doctor says the drug is safe WITH exercise because with exercise you'll know if your heart is being affected by the drug.

Unfortunately, exercise will neither protect you nor warn you of the onset of heart or lung problems. We examine our weight loss patients every two weeks, including a cardio-pulmonary (heart & Lung) examination, and a review of ANY changes since their last visit. The presence of a NEW heart murmur is the best indicator at present of possible heart valve problems, as is the onset of breathlessness at rest, ankle swelling, or shortness of breath lying down. The best diagnostic tool is an echocardiogram that bounces sound waves off your heart structures and displays them on a television screen. The only problem here is that up to 20% of women in this country may have "mitral valve prolapse"(MVP) with similar echocardiographic and structural findings. Whether the use of serotonin elevating substances in people with MVP predisposes them to increased risk of heart valve degeneration is unknown. The sheer numbers of people who have used these drugs over the last twenty five years is encouraging. This is somewhat like lightning strikes; the likelihood of being hit is statistically small, but that is slight comfort when the hair on your neck is rising.

o what happens if I don't exercise? And if there's any chance this drug could affect my heart with or without exercise wouldn't I just be better off exercising and watching my diet?

Exercise will help with weight loss when used in conjunction with a reasonable diet. The pills by themselves will NOT make you lose weight. You may have success with diet and exercise alone, but keep in mind a few points:You must burn 4,000 calories a week more than you take in to lose one pound of fat.

The average female requires 14,000 calories per week (2,000 calories / day). Fasting will make you lose weight, but you'll lose as much muscle and water as fat. When you start eating again, you'll put on two pounds of fat for every pound of muscle, not counting water weight.Best bet is to eat 4 or more times a day with small feedings throughout the day.

TANSTAAFL! ("There Ain't No Such Thing As A Free Lunch)

See also: Exercise Nutrition for Healthy People

and Is It Time for a Weight Loss Program?



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