Why Lorcaserin And Other Weight Loss Drugs Fail To Deliver

How Does Lorcaerin Work?

Humans and other animals produce serotonin, a protein hormone that plays a role in appetite. It binds to specific cell receptors including the 5HT2C serotonin receptor and thus regulates hunger. Lorcaserin is a weight loss drug that was designed to mimic the action of serotonin and bind to the 5HT2C receptor to suppress appetite. On the outset this seems logical because if a person doesn’t feel hungry they’ll feel less inclined to eat. But nothing is ever so simple.

There was a serious flaw in Arena’s research. The problem with lorcaserin’s studies is that the drug trials were not representative of the general population. After initial testing, Arena selected just over 7000 candidates for two phase 3 trials of lorcaserin’s efficacy as a weight loss drug.

The BLOOM Trial for Lorcaserin?

BLOOM which is an acronym for Behavioral Modification and Lorcaserin for Overweight and Obese Modification was the first phase 3 trial. This study took place over a two-year period and involved 3182 overweight or obese males and females who were randomly assigned to either a lorcaserin group (receiving 10 mg twice a day) or a placebo group (receiving an inert substance that doesn’t do anything for or to the body).

BLOOM’s had two main objectives, the was to assess lorcaserin’s effect on weight over the course of a year. The second top objective was to determine if patients who received lorcaserin could keep the weight off during the second year. In other words, to test whether or not lorcaserin would cause weight loss and help patients keep it off. *

BLOSSOM Trial for Lorcaserin

The company also conducted a second phase 3 trial called BLOSSOM for Behavioral Modification and Lorcaserin Second Study for Obesity Management. This study was only one year in duration and involved 4008 overweight or obese males and females. This group also had an objective which was to determine if lorcaserin could cause weight loss over the course of one year. There was a difference between the BLOOM and BLOSSOM studies. BLOSSOM patients were randomly assigned to one of three groups: a group receiving 10 mg of lorcaserin twice a day; a group receiving 10 mg lorcaserin once a day; or a placebo group.

But the company immediately made a serious error because the sample sizes were far too small to give a clear picture of how lorcaserin would affect the health of people who took the drug. In other words there is no way to know if lorcaserin is safe for human use. To have an accurate picture they should have taken a much larger sample size. And according to the FDA review, the BLOSSOM study had to be revised because it was initially designed for less than 4000 candidates.

Although it is scientifically impossible to have perfect confidence in the outcome of any study i.e. there will always be uncertainties, unintended consequences and side effects,  large sample sizes provide considerable data, and increases the accuracy of the results. Only Arena knows why they selected a relatively small population.