Weight Loss Medications - Stimulants
by Phillip Treadwell, PharmD

 

You may have already read about the fat-blocker , Orlistat (Xenical®). This article will focus on the most commonly used weight loss drugs- the stimulants. These drugs have been in clinical use for decades, and many different compounds and brand names are available. We will look at some of the similarities and differences within this class of agents and try to clarify the risks and benefits of these products.

These drugs all share the similarity of altering the way the body uses neurotransmitters, chemicals in the nervous system responsible for thought, feeling and the ability to move. All brain and nervous system function is mediated through neurotransmitters. Therefore, altering the function and fate of these chemicals can have profound effects on the mind and body. Some of these changes can be beneficial and some can be detrimental. The balance of these effects will be determined by the drug selected and the health status and body chemistry of the person taking the drug.

Many products are currently available including: phentermine (Fastin®, Adipex®, Bontril® and others), phendimetrazine (Bontril®, Prelu-2® and others), diethylpropion (Tenuate®) and sibutramine (Meridia®) among others. This group of drugs also included the notorious products fenfluramine (Pondimin®), and dexfenfluramine (Redux®) which are now banned by the FDA. Pondimin® and Redux® were pulled from the U.S. market because of pulmonary hypertension and heart valve disorders. These side effects were occasionally fatal, but seem to be extremely rare or non-existent with the agents still on the market. Even so, there are side effects that are very worrisome with this entire class of products. Chief among these is the risk of hypertension, or the worsening of this disorder in those already affected. This has the potential of causing strokes or heart attacks and has lead to lawsuits based on this premise. There is also the risk of irregular heartbeats, insomnia and anxiety. Addiction to these agents may also occur although it is thought to be less common with Meridia®. The major disadvantage of Meridia® is its higher price compared to other products in this class.

These drugs are all somewhat effective at assisting in weight loss. They work to decrease appetite and thereby decrease caloric intake. They may also cause some weight loss by increasing metabolism. The problem with this approach is that this type of weight loss is very difficult to maintain. It is based upon a “false” decrease in appetite that disappears when the drug is stopped. These drugs do not help teach new eating habits, unless the person taking them is very motivated to note the amount of calories consumed while taking the product and then to force himself or herself to continue this intake once the medication is stopped.

Based upon these problems, I would only recommend these products for overweight people who are young, otherwise healthy and very motivated to lose weight, but who need the psychological jump start of early, quick weight loss to get started with a program. These drugs should only be taken when you and your physician have, together, assessed the risks and benefits and determined if they are appropriate for you.