Well, it is the first anti-obesity drug approved by the FDA in 13 years (last one was Roche’s Orlistat, marketed as Xenical in most countries). It has side effects (everything has side effects), but it is something new.
Basically, orlistat works preventing the absorption of fats from the human diet. Lorcaserin switch off the appetite. Orlistat is a lipase inhibitor. Lorcaserin (former APD-356) is a 5-HT2C agonist, so it is a CNS drug. More important, it demonstrates that touching selectively (very selectively) a 5-HT receptor you can regulate appetite. Or so it seems, because the exact mechanism of appetite regulation is not yet known.
I really, really, really hope we are not seeing a new Rimonabant here (former SR141716, marketed by Sanofi-Aventis) which was a CB1 inverse agonist and was withdrawn in 2008 due to the risk of serious psychiatric problems and even suicide.
CNS is a tricky field, but the question is we need new CNS drugs. With all the risks related only a few companies are willing to give it a try.