Dear DOCTOR Owen:

I bought an over-the-counter appetite suppressant from the drugstore and found that it works! I was surprised at this and thought that maybe my mind was playing tricks on me—possibly the “thought” of taking a pill makes it work. Do these medicines work, and how? Are they safe? Does the effect last?

Tricked?

Dear “Tricked”:

Yes. The effect you have noted is real. These pills do have an appetite-suppressant effect—more on some individuals than on others. What you took was no doubt phenylpropanolamine, under the trade name Dexatrim® at most stores. This decongestant medication has been available commercially since 1930, and has been used to elevate low blood pressure.

Phenylpropanolamine is a non-methylated form of Ephedrine (also derived from a popular weight-loss agent known as the herb Ma Haung—which is the herb Ephedra). The Food and Drug Administration (FDA) approved phenylpropanolamine in 1976 as a safe and effective non-prescription appetite suppressant. The molecule is the same basic chemical structure from which amphetamine is derived. The only difference is a single hydroxyl molecule, which often has stimulatory effects like amphetamine and can elevate blood pressure and pulse. Phenylpropanolamine appears to stimulate the Beta-III nerve receptor, which may play a role in metabolism.

Like amphetamines, the appetite-suppressing action of Dexatrim® seems to diminish with time. Recent studies suggest that the metabolism-enhancing effect may remain, however. The maximum dose for decongestant effects is 150 milligrams; maximum weight-loss dose recommended is 75 milligrams.

An article in Obesity Research, Vol. 7, No. 4, reported on studies conducted at Pennington Biomedical Research Center in Baton Rouge, Louisiana. The researchers there reported that phenylpropanolamine was effective at about 0.5 kilograms (1 pound) of weight loss/week, for a total of 5 kilograms (10 pounds), and kept the weight off after stabilization. Furthermore, the dose used (37milligrams) was half that found in commercial preparations, yet was just as effective. No side effects were seen at these lower doses, compared to the placebo.

Many prior studies have found similar results at higher doses. Phenylpropanolamine is the most frequently prescribed diet medication in South America, and recommendations are to use it over a period of many years. Also, Latin countries have a much more liberal policy than the Anglo countries regarding diet treatments.

As with any medication used for a chronic condition, I always ask patients: “Are you willing to take this medication forever?” If the answer is “no,” it is useless to start in the first place. If the answer is “yes,” though, then I always recommend combining behavioral and exercise methods to improve results.

Over the next 10 years, more and more agents will become available to stimulate the Beta-III receptor of the nervous system, as a true metabolic effect can be seen. It remains to be proven if these newer agents are any more effective than they were in 1930. They certainly will be more expensive! It now takes about $500 million of research to get a drug approved by the FDA and on the market.

People still ask me what they can take to lose weight, but few ever ask me what they can remove! Here is a drug that you can take. While it may aid in weight loss, do not expect it to make you thin, as that will require removing calories.

Author’s Note: During editing of this article, the FDA recommended the removal of phenylpropanolamine from all available medication, as several deaths occurred which may have been linked to its use. The deaths were from cardiac rhythm disturbances. Since that recommendation (October 2000), many other countries have recalled all products containing phenylpropanolamine. If you have these compounds at home, it is recommended that you dispose of them.