Belviq (lorcaserin) was a weight loss medication marketed by Esai, Inc. In February 2020, the U.S. Food & Drug Administration (FDA) asked Esai to conduct a Belviq recall because of clinical trial data suggesting lorcaserin was associated with an increased risk for cancer, including pancreatic, colorectal, and lung cancer.

Belviq and Belviq XR: Background

Locaserin was intended to be prescribed in conjunction with a low-calorie diet to aid weight loss in obese adults who suffer from weight-related health problems. The medication controls appetite by activating receptors in the brain that regulate serotonin, a neurotransmitter associated with feelings of satiety and satisfaction.

Locaserin was developed by Arena Pharmaceuticals, which won FDA approval to market Belviq in 2012.  Belviq XR – an extended version of locaserin – was approved four years later.

Clinical trial data submitted to the FDA indicated that nearly half of dieters without Type 2 diabetes who used Belviq lost at least 5% of their starting weight — or an average of 12 lbs. — over a year, compared with 23% of those taking a placebo. The labeling for Belviq also recommended that the drug be discontinued if users failed to lose 5% of their body weight after 12 weeks, as longer treatment was unlikely to lead to meaningful weight loss.

Following its approval, Esai, Inc. held the rights to market Belviq in the United States. The company acquired the global rights to sell Belviq and Belviq XR in 2017.

Belviq Side Effects

The most common Belviq side effects seen in non-diabetic patients include headache, dizziness, fatigue, nausea, dry mouth and constipation. The most frequently observed side effects among diabetics include low blood sugar, headache, back pain, cough and fatigue.

Belviq should not be taken during pregnancy, as weight loss in pregnancy can harm an unborn baby. Nursing mothers should not use Belviq, since it is not known if locaserin passes into breast milk.

Before taking Belviq, patients should tell their doctor if they have diabetes, congestive heart failure, a heart valve disorder, sickle cell anemia, leukemia or myeloma, kidney or liver disease, or a physical deformity of the penis (such as Peyronie’s disease).

Because locaserin may be habit forming, Belviq should be used only by the person for whom it was prescribed and stored where it can’t be easily accessed by others.

Belviq can impair thinking or reactions, so those using locaserin should be careful while driving or doing anything else that requires alertness.

Patients should stop taking Belviq and contact their doctor right away if they experience:

  • Unusual changes in mood or behavior, thoughts of suicide or self-harm;
  • Dry eyes, blurred vision;
  • Feelings of being outside of their body;
  • Memory problems, trouble concentrating;
  • Breast swelling (in women or men), nipple discharge;
  • Penis erection that is painful or lasts longer than 4 hours;
  • Any indication of heart problems, including fast heart rate, trouble breathing, dizziness, ongoing weakness, or swelling in the arms, hands, legs, or feet;
  • Agitation, hallucinations, fever, fast heart rate, overactive reflexes, nausea, vomiting, diarrhea, loss of coordination, fainting and other symptoms that might signify high levels of serotonin in the body.
  • Severe nervous system reaction, including very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, or feeling like they might pass out.

Any signs of an allergic reaction to Belviq – hives; difficult breathing; swelling of the face, lips, tongue, or throat – require emergency medical attention.

Heart and Cancer Concerns Delayed Belviq Approval

Arena Pharmaceuticals initially sought approval for Belviq in 2010. However, the FDA declined at that time because animal studies suggested locaserin might increase the risk for certain tumors.

There was also concern that Belviq might cause heart valve problems in some people.  A similar serotonin-based weight loss drug — fenfluramine — was removed from the market in 1997 because of similar heart concerns.

Eventually, Arena was able to provide data showing that heart problems would not occur at the low doses at which Belviq would be prescribed. The company also convinced the FDA that the tumors seen in some studies were specific to the animals used in those experiments.

When the FDA finally approved Belviq in 2012, Arena was required to a post-marketing clinical trial to assess the drug’s potential to cause heart attacks and strokes.

Belviq Cancer Warning and Recall

According to a Drug Safety Communication published by the FDA on January 14th 2020, data from from that trial suggested cancer occurred more frequently among subjects taking Belviq compared to those given a placebo. The study in question followed approximately 12,000 participants over a period of five years.

“At this time, the cause of the cancer is uncertain, and we cannot conclude that lorcaserin contributes to the cancer risk,” the agency stated. “However, we wanted to make the public aware of this potential risk. We are continuing to evaluate the clinical trial results and will communicate our final conclusions and recommendations when we have completed our review.”

The FDA had concluded its review by the following month, at which time the agency confirmed that locaserin was likely associated with an increased risk of cancer, especially pancreatic cancer, lung cancer, and colorectal cancer.

“As noted in a new Drug Safety Communication issued today, patients should stop using the medication Belviq and Belviq XR (lorcaserin) and talk to their health care professionals about other treatment options for weight loss,” Janet Woodcock, director of the FDA’s Center for Drug Evaluation and Research, said in February 13th press release.

The FDA also asked Esai to pull Belviq and Belviq XR from the market. While the company disagreed with the agency’s findings, it ultimately complied with the FDA’s request.

  1. FDA (N.D.) “Belviq: Highlights of Prescribing Information”
  2. PRNewswire (October 2010) “FDA Issues Complete Response Letter for Lorcaserin New Drug Application”
  3. (June 2012) “U.S. FDA APPROVES ANTIOBESITY AGENT BELVIQ (lorcaserin HCl) for Adults”
  4. FDA (January 2020) “Safety clinical trial shows possible increased risk of cancer with weight-loss medicine Belviq, Belviq XR (lorcaserin)”
  5. FDA (February 2020) “Belviq, Belviq XR (lorcaserin) by Eisai: Drug Safety Communication – FDA Requests Withdrawal of Weight-Loss Drug”
  6. FDA (February 2020) “FDA In Brief: FDA Requests Voluntary Withdrawal of Weight-Loss Medication After Clinical Trial Shows an Increased Occurrence of Cancer”
Last Modified: February 20, 2020

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