Some posters on Seeking Alpha have suggested Arena Pharmaceuticals, Inc.'s (ARNA) Lorcaserin (Belviq) is as effective as Vivus, Inc.'s (VVUS) Qsymia, especially the moderate dose of Qsymia (7.5 mg Phentermine/46 mg Topiramate), compared with Belviq 10 mg twice daily. That is not supported by data.
The dosages approved by the FDA. From the FDA press announcement, "The recommended daily dose of Qsymia contains 7.5 milligrams of phentermine and 46 mg of topiramate extended-release. Qsymia is also available at a higher dose (15 mg phentermine and 92 mg of topiramate extended-release) for select patients." Belviq will be dosed at 10 mg bid (Prescribing information).
The data on average weight loss.
Qnexa: From the FDA briefing document for the advisory panel meeting on Qnexa (now Qsymia), "Average weight loss achieved in subjects receiving QNEXA Top dose was 10.9% (OB-302) and 9.8% (OB-303), compared with subjects receiving placebo (OB-302, 1.6%; OB-303, 1.2%). Weight loss was also achieved in subjects receiving QNEXA Mid dose (OB-301, 8.5%; OB-303, 7.8%) and Low dose (OB-302, 5.1%)".
Belviq: From the FDA briefing document, "In pooled efficacy analyses, the mean placebo-subtracted weight loss at Week 52 from baseline with lorcaserin 10 mg BID was 3.3%".
The data on response rate (patients losing at least 5% of baseline body weight).
Qsymia: From table 3 in the briefing document for mid dose of Qnexa, the percentage of subject achieving at least a 5% weight loss from baseline were 62.1% and 15.5% for Qnexa and placebo, respectively, in OB-301 trial. In the OB-303 trial, the percentage of subjects achieving at least a 5% weight loss from baseline were 62.1% and 20.8% for Qnexa and placebo, respectively.
Lorcaserin (Belviq): "Approximately 47% of patients on lorcaserin 10 mg BID and 23% of patients on placebo lost at least 5% of baseline body weight at Week 52."
Qsymia is more effective than Belviq. The average weight loss for patents was greater for Qsymia than Belviq. The response rate, as judged by patients losing at least 5% of baseline body weight, was greater for Qsymia than Belviq. Orexigen Therapeutics, Inc.'s (OREX) obesity drug under development, Contrave, has not been approved.
Disclosure: I am long ARNA.
Additional disclosure: I may buy VVUS shares in the next 72 hours.