Shares of Vivus Inc (VVUS.O) surged 12 percent on Monday, buoyed by data that showed strong growth in weekly prescriptions for its Qsymia pill, the latest fat-fighter on the U.S. market.
Healthcare research firm Symphony Health Solutions reported a 44 percent jump in Qsymia prescriptions for the week ended November 12, while another industry body, IMS Health, pointed to a 15 percent rise in prescriptions during the same period, said Cowen & Co analyst Simos Simeonidis.
"Given the discrepancy between vendors's numbers and actual scripts in 3Q12 ... we don't trust these script numbers 100 percent and we'll only get comfortable with them once we see 4Q12 results in late February," Simeonidis wrote in a note.
Qsymia's initial sales, released by Vivus in early November, came in well below analysts' expectations, prompting concerns about the fate of the much-hyped drug.
Shares have lost 23 percent of their value since then to their Friday close.
"We'll probably have quite a few more up-and-down weeks in the first few months, not only in terms of scripts reported, but especially in terms of investor sentiment, possibly due to unrealistic expectations on either side of the aisle," analyst Simeonidis said.
The analyst has a "neutral" rating on Vivus stock, with a price target of $11.48.
Vivus shares touched a high of $13.04 in early trading on Monday, losing some of the gains to $12.66 by mid-morning on the Nasdaq.
Despite the jump on Monday, the stock is still more than 40 percent lower than the price it traded at during the September launch of Qsymia.
(Reporting by Zeba Siddiqui in Bangalore; Editing by Sriraj Kalluvila)