Lorcaserin hydrochloride is a drug intended for weight loss and weight management in obese patients. The diet pill is a serotonin 2C receptor (5-HT2C) agonist and anorectic. In 2009, Arena Pharmaceuticals filed a new-drug application for lorcaserin hydrochloride with the U.S. Food and Drug Administration (FDA). In October 2010, the FDA rejected lorcaserin in its form at the time, citing concerns over efficacy and links to cancerous tumors in lab rats. The proposed trademarked name then was Lorqess®.
Serotonin 2C receptors are found in many areas of the brain, and those within the hypothalamus are believed to be responsible for regulating a person's appetite and metabolism. As a serotonin 2C agonist, lorcaserin is thought to activate these receptors and produce chemicals that suppress hunger. A patient taking lorcaserin feels full faster, eats fewer calories and, in turn, loses weight.
The diet pill is intended for two groups of patients, those with a body mass index (BMI) of 30 or more, and those with a BMI of 27 or more plus a weight-related health condition such as high blood pressure, elevated cholesterol or type 2 diabetes. Two Phase 3 clinical trials were conducted for the diet pill, BLOOM (Behavioral modification and Lorcaserin for Overweight and Obesity Management) and BLOSSOM (Behavioral modification and Lorcaserin Second Study for Obesity Management). These double-blind clinical trials evaluated the weight loss pill against a placebo for two years, with both groups also receiving diet and exercise counseling.
The results for 3,182 patients were published in the New England Journal of Medicine in July 2010. The authors reported that 47.5 percent of patients in the lorcaserin group lost 5 percent or more of their body weight, compared to 20.3 percent of the placebo group. Of those patients with weight loss who stayed on lorcaserin, 67.9 percent maintained the weight loss for one year. Without the diet pill, only 50.3 percent maintained the previous weight loss. The most frequently reported side effects included headache, dizziness and nausea.
As a serotonin 2C receptor agonist, Lorqess® is similar to the banned drug fenfluramine, or Fen-Phen. Arena Pharmaceuticals reports, however, that Lorqess® showed none of fenfluramine’s toxic heart effects in clinical trials; the company credit's lorcaserin's greater receptor selectivity. Arena Pharmaceuticals continued to work in late 2010 with the FDA toward approval of Lorqess®. It also was seeking approval of the drug in Europe.