STUART WASSER MD               ROCKVILLE CENTRE NY              516 594-2514
An exciting new medication has come to the market in June of 2013.  Belviq is similar to prior weight loss medications in that it effects serotonin physiology.  Serotonin has key roles to play in brain "pacemaker" activity, emotional regulation, and homeostasis.  Part of these functions includes regulating feelings of satiety, hunger and therefore weight.  It is interesting that there are a myriad of different receptors throughout the body that react to serotonin-sometimes in opposite directions.  However, it is the opposing directions of action that allows serotonin to stabilize brain function.

In considering the specifics of Belviq function, it stimulates the Serotonin 2C receptor (often referred to as the 5-HT2c receptor)..  Even though this receptor stimulates the target nerve, many of the target nerves themselves are inhibitory.  So we are increasing the inhibition of certain brain functions that lead to irritability and hunger; reducing such functions will lead to decreased food intake and hopefully weight loss.

The weight loss seen in studies was probably between 5-10 % which is significant but admittedly more modest than that seen with Qsymia.  However, it is important to remember that Qsymia is a combination of two different medications; the combination of which produces a weight loss of 10-15%.  Each of the components has a different mechanism of action than Belviq.  Also, Belviq is likely as strong or stronger than either component of Qsymia alone.  Although it remains to be proven, I suspect that combining Belviq with either medicine component of Qsymia (both are available generically) may lead to even more profound weight loss.

Now it is appropriate to be cautious with a new Serotonin drug given the history of heart valve problems caused by Redux (dexfenfluramine) and fen/phen.  Those drugs led to profound release of seratonin.  The released serotonin stimulated serotonin 2B (not 2C) receptors in the heart valves leading to overgrowth of tissues in the heart valve (and pulmonary tissues as well?).  Many other drugs (ecstasy, migraine medications)which cause significant release of Serotonin also have led to similar heart problems.  Belviq stimulates the 2C receptor directly and does not lead to serotonin release.  Therefore the heart tissues are not stimulated.  The release of the drug was delayed for years while this issue was studied and no heart valve problems have been identified.

My first approach to patients, based solely on price, will still be the generic equivalent of qsymia.   However, Belviq represents a viable option for patients who do not get a sufficient benefit or cannot tolerate the first line treatment.