Another Look at Two Weight Loss Medications

Lorcaserin and Phentermine Topiramate make the short FDA list of antiobesity medications

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) The FDA has approved very few medications to treat obesity. Serious side effects have forced medications like fenfluramine (Pondimin) and sibutramine (Meridia) to be withdrawn from the market.

Faced with a growing need for anti-obesity medications, two medications introduced in 2012 — Belviq (lorcaserin) and Qsymia (phentermine/topiramate ER) — have proven effective in causing weight loss without serious side effects.

Researchers recently updated the information now available for these two medications.

"Discuss weight management options with your doctor."

The lead author of this review of anti-obesity medications was Grace Shyh, BS, PharmD, from the Department of Pharmacy at Kingsbrook Jewish Medical Center in Brooklyn, NY and Montefiore Medical Center in Bronx, NY.

Dr. Shyh and Angela Cheng-Lai, PharmD, BCPS, reviewed the effectiveness and safety of Belviq and Qsymia and compared them with other available medications to treat obesity.

Drug manufacturers know that the serotonin receptor in the brain can be a target of medications to cause weight loss. Belviq works to block one of the types of serotonin receptors. Belviq works differently from other medications used to block serotonin in the past because it blocks a very specific serotonin receptor. Blocking this type of serotonin receptor does not cause hallucinations or heart and lung effects that other anti-obesity medications have. Belviq has been shown to decrease food consumption and increase weight loss.

Three advanced clinical trials testing Belviq have been done. These were named BLOOM, BLOSSOM and BLOOM-DM. During the first year of the BLOOM study, 3,182 patients received either 10 mg Belviq twice a day or a fake placebo pill. At the end of a year, some Belviq patients continued taking the medication or were given placebo. All patients ate a standard diet and had required exercise.

At the end of two years, 47.5 percent of the patients in the Belviq group and 20.3 percent who took placebo had lost over 5 percent of their body weight.

There was an average weight loss of about 12.8 pounds in the Belviq group and 4.8 pounds in the placebo group after one year. Over 22 percent of patients in the Belviq group lost more than 10 percent of their body weight, compared to 7.7 percent of patients who took placebo.

Patients in the BLOOM study had a significant decrease in blood pressure, total cholesterol, low density lipoprotein (LDL) and hemoglobin A1C, an important marker of diabetes status. By year two, however, cholesterol, LDL and triglycerides increased in both study groups, and those patients who continued to take Belviq in year two of the study did not lose additional weight.

In the BLOSSOM trial, 4,008 patients were given either 10 mg Belviq twice a day, 10 mg Belviq once a day or placebo. Patients in this study had heart valve disease. At the end of a year, weight loss of at least 5 percent body weight was seen in 47.2 percent of those who received the medication twice a day, 40.2 percent who took 10 mg once a day and 25.0 percent of patients who took placebo.

The BLOOM-DM trial enrolled patients with diabetes. The weight loss results were similar to the BLOOM and BLOSSOM studies. More patients lost more than 5 percent of their body weight with Belviq twice daily (37.5 percent) and Belviq once daily (44.7 percent) when compared with placebo (16.1 percent). This study showed that Belviq could cause weight loss and help control glucose in patients with type 2 diabetes.

Some patients who took Belviq had side effects from the medication. Inflamed nose and throat was experienced by 16.4 percent of patients, upper respiratory infections by 14.5 percent, headache by 7.2 percent, nausea by 3.5 percent and dizziness by 1.7 percent.

Since other medications used to treat obesity caused heart disease, the researchers looked at rate of heart valve disease and found that it did not differ from that found in the groups of patients taking placebo. They concluded that, “In general, [Belviq] poses a relatively good safety profile and is well tolerated.”

Because of the number of people who also take medications that work with the serotonin system, consideration must be given before Belviq is taken with medications such as antidepressants, tryptophan, dextromethorphan and St. John’s Wort.

Qsymia (phentermine/topiramate ER) was studied in four trials, called CONQUER, SEQUAL, EQUIP and EQUATE.

In the CONQUER study, 2,487 overweight or obese patients took medications at doses of 7.5 mg phentermine/46 mg topiramate ER (lower dose of Qsymia), 15 mg phentermine/92 mg topiramate ER (higher dose of Qsymia) or placebo for 56 weeks.

At the end of the study, the average weight loss with placebo was 1.2 percent of body weight. The patients who took the lower dose Qsymia had an average weight loss of 7.8 percent and the patients taking the higher dose of Qsymia lost 9.8 percent of their body weight.

The SEQUAL study enrolled 676 people who had already completed the CONQUER study. They were treated for another year.

The SEQUAL study showed that weight lost in the CONQUER study continued for the next year with weight losses of 1.8 percent of body weight in the placebo group, 9.3 percent in those taking the lower dose of Qsymia and 10.5 percent in patients taking the higher dose.

An important finding in the SEQUAL study was that people who did not have diabetes at the start of the trial were less likely to develop it if they took Qsymia, compared with those patients who took placebo. Blood pressure, fasting glucose, hemoglobin A1C, LDL and triglycerides were all decreased in patients taking Qsymia compared to placebo.

Study participants in the EQUIP study were given placebo or doses of Qsymia at 3.75 mg phentermine/23 mg topiramate ER or 15 mg/92 mg for 56 weeks. As in CONQUER and SEQUEL, the patients given the study medications lost significantly more weight than those receiving placebo.

The EQUATE trial lasted 28 weeks and involved 756 obese participants. This study looked at effects of giving phentermine or topiramate individually with the effects of giving the two medications combined. Participants were given placebo, 7.5 mg or 15 mg phentermine, 46 mg or 92 mg topiramate ER or the combination at 7.5 mg phentermine/46 mg topiramate ER or at 15 mg/92 mg.

The results of this study showed greater weight loss by people taking the combination of medications (Qsymia) than with either medication alone. People who took phentermine 7.5 mg/topiramate ER 46 mg had a weight loss of 8.5 percent of their body weight and those taking 15 mg/92 mg had a weight loss of 9.2 percent.

Adverse events were reported in patients receiving Qsymia, and these occurred more in those receiving higher doses of the medications. An important warning on the use of topiramate is that it is known to cause birth defects. Psychiatric patients, depressed people and people with heart or vascular disease, glaucoma or overactive thyroid are recommeded to not be given Qsymia.

The researchers reviewing studies on these two medications concluded that weight loss appeared to be greater with Qsymia compared to Belviq or orlistat, one of the only other weight loss medications available.

Availability of these two medications may impact who gets to take them. Qsymia is a controlled medication and is only available through certified mail-order pharmacies. Belviq is available at more pharmacies, making it available to more patients.

Price is another consideration to patients, and the researchers estimated the monthly cost of Belviq to be $199.80 if taken as 10 mg twice daily. They estimated the cost of Qsymia at between $144 and $220.50 a month, depending on dose.

Andre F. Hall, MD, board certified obstetrician/gynecologist at Birth and Women's Care in Fayetteville, NC, said, “Currently there are three prescription medications on the market most often used for weight loss. Their trade names are Adipex, Qsymia, and Belviq.

"Adipex which is by far the oldest and works as an appetite suppressant which also increases the metabolism hence causing weight loss. Qsymia, approved in 2012, combines the beneficial effects of adipex with topamax. Topamax, historically has most commonly been used for headaches but has been shown to suppress appetite also," Dr. Hall said.

"The major side effect noted with adipex containing medications is some insomnia. The lack of insomnia in the third medication, Belviq, makes it attractive to those sensitive to the sleep disturbances. Belviq works on receptors in the brain which effectively convince an individual that they are not hungry. The major drawback to Qsymia and Belviq is that as they are new they are poorly covered by many insurers and hence may be expensive," he said.

Dr. Hall added, "All of these medications, while excellent in stimulating weight loss, should be combined with a program of exercise and diet. One must make a lifestyle change so that once the goal weight is reached, the results are long lasting."

This review was published in the January/February issue of Cardiology in Review.

The authors did not disclose any conflicts of interest.

Review Date: 
December 9, 2013
Last Updated:
December 10, 2013