Lorcaserin Successful in Treating Obesity
Investigational drug Lorcaserin effectively helps obese people lose weight, according to a new report. In a recent study, people taking Lorcaserin experiences weight loss of 4.0-7.9 pounds over 12 weeks.
"Lorcaserin demonstrated excellent weight loss in this study, coupled with excellent tolerability and a positive impact on associated physical measures and most lipid measures in obese patients," said Steven Smith, MD, of the Pennington Biomedical Research Center in Baton Rouge, Louisiana, in a presentation at the American Diabetes Association meeting in Washington.
Lorcaserin Versus Phen-Fen
Lorcaserin works by selectively stimulating the 5-HT2C serotonin receptor in the hypothalamus, which affects satiety and metabolic rate.
In contrast, the anti-obesity drug combination Redux/Phen-Fen (phentermine-fenfluramine) - removed from the market because of its associations with cardiovascular complications - worked by non-selective stimulation of both central and peripheral 5-HT2B receptors.
Fen-phen's non-selectivity may have caused some adverse events, including valvulopathies and primary pulmonary hypertension, according to Dominic P Behan, PhD, chief scientific officer for Lorcaserin manufacturer Arena Pharmaceuticals, in San Diego.
Clinical Trial
The randomized, double-blind, 12-week study was conducted at about US 40 sites and included 469 obese women and men (87% vs.13%, respectively).
Participants' body mass indices (BMI) were 29-46 kg/m2 (mean BMI 36.4 kg/m2). Average baseline weight was 100kg (220 lbs).
All participants were screened using echocardiography at baseline and at the end of the trial, because of concerns about 5-HT2 serotonin receptor agents. Participants receiving medication for dyslipidemia (high cholesterol) or hypertension were not disqualified from the study. However, they were required to abstain from using alcohol during the study, and they received no advice on diet or exercise, so that the drug's effect was not diluted.
Each participants was randomized to receive Lorcaserin (10 mg, 15 mg or 20 mg) or placebo. The study's primary endpoint was weight- reduction in participants completing the study.
Results
Results showed that Lorcaserin was associated with significant, dose-dependent weight loss. Weight loss increased with dosage and was statistically significant in all three treatment groups, compared with placebo.
Participants' BMI showed significant, dose-dependent improvements for all three lorcaserin doses. Also, waist circumference and cholesterol showed significant improvement at the 15- and 20-mg doses, and fasting plasma glucose significantly improved at the 20-mg dose.
Positive but insignificant trends towards improvement occurred for in low-density lipoproteins (LDLs) and triglycerides, and blood pressure was unchanged.
Also of note, a small, non-dose-dependent significant decrease in HDL levels (3.3%-3.5%) led to an insignificant change in LDL/HDL ratios. However, this change is unlikely to be harmful and may be balanced by improvements in other parameters, Dr Behan reportedly said.
The primary adverse events were headache, nausea, dizziness, vomiting, dry mouth, nasopharyngitis, fatigue, and urinary tract infections. Four serious adverse events occurred and included one case each of pneumonia and a kidney stone in the placebo group, clinical depression in the 10-mg group, and a new-onset seizure in the 20-mg group.
No apparent drug-related effects occurred on heart valve function or pulmonary artery pressure.
Regarding whether or not weight loss may plateau with extended treatment with lorcaserin, Dr Behan replied that more data were required to be sure, but that thus far the observed weight loss was progressive.
According to Dr Behan, phase III studies will begin later this year, pending discussions with the FDA.
Sources: ADA: Investigational Drug Produces Significant Weight Loss for Obese (CME/CE), MedPage Today, June 13, 2006. APD356, an Orally-Active Selective 5-HT2C Agonist, Reduces Body Weight in Obese Adult Men and Women. Smith S et al, presented at the 2006 American Diabetes Association Scientific Sessions, June 12, 2006.
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