Combination pill effective, but expensive

We read with interest, the trial by Aronne et al. (1) examining the effect of combined phentermine/topiramate ER (Qsymia) on weight reduction versus the effect of the individual agents. Weight loss on the combined drug was greater than each of the individual drug groups, which in turn produced weight loss generally consistent with a past meta-analysis of randomized trials that included phentermine and topiramate (2). These are promising results for patients seeking assistance in weight loss. Qsymia is a costly drug, though, whereas its individual components are relatively inexpensive. We regret that the investigators did not examine the effect of phentermine and topiramate given together as separate doses. While combination medications typically are admittedly associated with increased patient compliance in patients with obesity and diabetes (3), simple topiramate is available in doses that would allow approximation of the doses of topiramate ER present in Qsymia. Furthermore, the pharmacokinetics of simple topiramate, with its 19 h half-life (versus the 55 h half-life of topiramate ER), would support its use as a twice daily agent in concert with daily phentermine (4).