MOUNTAIN VIEW, Calif. ( TheStreet) -- Check out the acceleration in the number of prescriptions written for Vivus' ( VVUS - Get Report) weight-loss pill Qsymia. The uptick starts at the beginning of July when Vivus was finally able to sell Qsymia in retail pharmacies instead of by mail order only.

Vivus has also started direct-to-consumer advertising of Qsymia.

Two weeks of surging script numbers isn't enough to draw any firm conclusions about a Qsymia marketing rebound but it's definitely something to watch closely.

Meantime, the nascent launch of Arena Pharmaceuticals' ( ARNA - Get Report) Belviq looks underwhelming. At best, Belviq scripts are tracking in line with Qsymia's early performance (not depicted on the chart above.)

But factor in the considerable number of free Belviq samples being given out -- as much as 60% of the total scripts to date -- and Arena's weight-loss pill has a long way to go to meet even diminished expectations.

Vivus has not set a date to report second-quarter earnings report but the consensus sales estimate for Qsymia is just under $8 million.

Here's a chart of the relative stock performance of Vivus and Arena since July 1: VVUS Chart VVUS data by YCharts

But look what happens when Orexigen Therapeutics ( OREX) is added to the chart: VVUS Chart VVUS data by YCharts

Investors are definitely running up the value of Orexigen in anticipating of a positive outcome from the cardiovascular safety study of its weight-loss pill Contrave.

-- Reported by Adam Feuerstein in Boston.

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.