Shares of anti-obesity drug makers are sinking for a second straight day after VIVUS Pharmaceuticals (VVUS) yesterday morning reported its quarterly results, including prescription data for its anti-obesity drug, Qsymia. In a conference call with investors yesterday morning, VIVUS reported that 5,560 prescriptions for Qsymia have been written since the drug was launched on September 17. In a note to investors earlier today, research firm Jefferies wrote that demand for the drug is tracking 30% below data provided by prescription tracking firm IMS (RX). Jefferies called this news surprising and slashed its price target on VIVUS' stock to $6 from $13. The weaker than expected prescription trend leaves VIVUS poised to generate revenue of $65M-$100M in 2013, versus the consensus estimate of about $230M, according to the firm, which maintained an Underperform rating on the shares. Meanwhile, VIVUS added on its call that it was concerned by the lack of coverage of Qsymia by insurers, as just 20% of patients are getting reimbursed for the medicine. The company said it would try to improve uptake of Qsymia by asking the FDA for permission to market the drug to select retail pharmacies. In early trading today, VIVUS sank 7.66% to $10.91. Other makers of anti-obesity drugs also declined, with Orexigen (OREX) sliding 5.94% to $4.69 and Arena Pharmaceuticals (ARNA) giving back 2.76% to $7.39.