Psychopharmacology

The New Generation of Weight-Loss Drugs: Which Is Best?

You must talk to your physician about the side effects, too...

Posted Feb 01, 2015

Suddenly, for the people struggling to lose weight but are failing to do so with diets and exercise alone? They now have help.  The FDA has approved four drugs for the treatment of obesity over the last two years.  While they will not have the potency of tapeworm eggs, a sure way of losing weight promoted about a hundred years ago, the drugs may prevent many from developing Type 2 diabetes and/or the health risks of high blood pressure or elevated cholesterol levels.

Unlike wrinkle cream or Botox, available even to those who do not need it, physicians are not supposed to prescribe them for skinny people who want to get skinnier. If your mother-of-the-bride dress may be snug for that May wedding, don’t expect a reputable physician to give you a weight-loss medication so you can go from a size 10 to a size 8. That is, unless you stand under four feet and wear a size 10 dress; this would mean that you really are obese. 

Other limitations to the use of these drugs have been recommended as well by Dr. Caroline Apovian, a physician from Boston University School of Medicine. She chaired a group from the Endocrine Society; a group tasked with the job of providing guidelines for physicians prescribing these drugs. Endocrinologists tend to specialize in the treatment of diabetes, and thus would be likely to prescribe these drugs to help obese patients with Type 2 diabetes lose weight.  Although most of the advice centered on preventing drug-drug interactions, (avoiding weight-loss drugs that contain phentermine or buproprion if the patient has high blood pressure) Dr. Apovian stressed the importance of diet, exercise and counseling. Obviously one of these weight-loss drugs is the magic potion that will banish excess fat forever.

What are these drugs and how effective are they? The drugs are: BELVIQ (generic name: lorcaserin); QSYMIA (a combination of two drugs:the generic names are phentermine and topiramate); CONTRAVE (a combination of two drugs: the generic names are buproprion and naltrexone); and SAXENDA (generic name: liraglutide).

The drugs differ in how they bring about weight loss. They all affect the brain, but in different ways. BELVIQ works with serotonin to increase a sense of fullness before much food has been eaten.  OSYMIA relies on a combination of phentermine, a type of amphetamine that works on the brain chemical dopamine to decrease hunger, and topiramate, a drug originally prescribed as an anti-epileptic drug that also increases satiety or early fullness after eating.  However, regarding topiramate, according to an article on the web site Drugs.com, “the precise mechanism of action of topiramate on chronic weight management is not known.” The naltrexone in  CONTRAVE has been used to treat alcohol and opioid dependency and bupropion  (trade name Wellbutrin) treats depression and smoking cessation. It affects dopamine and thus may decrease hunger.  Some believe that naltrexone decreases the pleasure experienced in eating, so theoretically, the dieter will lose the urge to eat a piece of molten chocolate cake or a bacon cheeseburger with onion rings. Or if this Contrave user does give into temptation and eat these foods, they won’t get any pleasure from doing so.

Saxenda was just approved at the conclusion of 2014. Saxenda has the same composition as Victoza, a drug used to treat type 2 diabetes, but Saxenda has not been approved to treat diabetes, only obesity. This drug does not affect the brain directly, as do the other drugs. Saxenda’s composition is similar to a naturally found compound in the intestines called glucagon-like peptide-1 receptor agonist (this will not be on a test) or GLP-1. This GLP-1 and the drug combine to help cells in the pancreas make and release insulin so that blood sugar levels stay normal. This compound can get into the brain and may affect regions of the brain involved with appetite, but not too much more is known about how this drug makes people eat less.   

The first three drugs are taken in pill form. Saxenda must be injected daily.

In order to be approved as a weight loss drug by the FDA, 5% of pre-treatment body weight had to be lost by 12 weeks in clinical trials.  Based on these results, physicians prescribing these drugs are told that if this doesn’t occur with their patients, then the drug may not be suitable for them and should not be taken any longer and/or the dose should be increased. 

So who can get the medication? If a person is healthy except for obesity, which translates into that he or she must have a BMI (body mass index) of 30 or more. BMI can be calculated by dividing one’s weight in kilograms by height in meters squared. For the arithmetic challenged, charts that convert your weight in pounds and height in inches to these metric measurements are available on the Internet, along with highlighted areas indicating obesity. For example, a 5’5” woman who weighs 180 pounds has a BMI of 30. A 5’10” man who weighs 210 pounds also has a BMI of 30.  However, if another medical condition like high blood pressure is present, a weight-loss drug can be given if the person has a BMI of 27.

Alas, the side effects of weight loss drugs must be considered as well.  One consideration is whether other drugs are being taken that might interact with the weight-loss drug and lead to serious medical complications. Like the monotonous voice reciting the side effects of medications being advertised on television, the potential side effects list is long and for some of the weight-loss drugs, perhaps intolerable or dangerous. For example, someone with a family history of thyroid tumors cannot take Saxenda, and some may not tolerate the nausea it causes. Contrave must not be used in people with seizure disorders and contains a warning about an increased risk of suicidal thoughts and behavior. Qsymia can cause mood disorders as well as depression, and should be avoided by people with a history of depression. It also is associated with cognitive problems such as decrease in attention, memory and word retrieval.

Belviq comes with the warning that it must not be taken if the patient is on one of a long list of drugs or herbal supplements, including St John’s Wort and tryptophan, for mood disorders.

And yes, every one of the drugs will be effective only if...you know what is coming...the patient follows a diet and exercises regularly!

So which is the best for you?  The choice depends on your personal overeating profile: Is your hunger uncontrollable, or do you have difficulty stopping when you are full? Do you have addictive-like cravings? The choice also depends on your medical profile, which includes your current medications, and underlying health problems such as diabetes or depression. Your physician will be the best and only judge of this. But knowing something about these drugs before consulting your healthcare giver will make you a full participant in the decision.