The prescription obesity marketplace may be near a tipping point. Jefferies analyst Thomas Wei sat in on investor updates for both Vivus, which makes Qsymia, and Arena, whose drug Belviq is marketed by Eisai.

Both have failed to make a major impression on the prescription marketplace since their launches, but Wei’s notes indicate that Vivus is continuing to struggle, while Arena is beginning to experience a lift.

Vivus has been struggling with several problems, among them, a failed jumpstart when health issues forced AstraZeneca ‘s Tony Zook to leave the job shortly after signing on.

The hope at the time was that Zook would find a company to partner up with. Wei says Vivus executives are still on the lookout but the search is taking longer than expected, leading the analyst to write that his team “remains cautious that a deal with a major pharmaceutical company will come to fruition.” 

At the same time, the company saw total prescriptions drop by almost 6% in November compared to October. Wei says the company’s 150 reps will focus on HCPs who prescribe anti-obesity therapies, which means between 20,000 and 25,000 providers. The analyst also notes that Vivus’s managed-care access is around 43%, as opposed to its 2013 goal of 50%.

In contrast, Wei sees Arena’s Belviq as approaching a positive level of momentum: Eisai upped its sales force to 400 and has teamed up with health insurer Aetna in a pilot program that includes Belviq as a covered medication. This is in addition to a free trial period and a co-pay card that could lower new user fees to $150 a month.

Yet Belviq’s future prospects appear to be driving Wei’s enthusiasm for the prescription drug. Eisai is currently testing the medication with phentermine—a component of Qsymia—which could help boost weight loss. Eisai expects results from the 12-week study to surface in July.