MOUNTAIN VIEW, Calif. ( TheStreet) -- Vivus' ( VVUS) plan to secure U.S. approval of its obesity drug has been derailed again by a cleft lip. Regulators at the U.S. Food and Drug Administration have asked Vivus to analyze existing healthcare databases to determine the incidence of oral cleft in the children of women treated with topiramate, the company said. Vivus' weight-loss drug Qnexa combines two currently marketed drugs: Topiramate, used to treat seizures and migraine headaches; and phentermine, used to curb appetite. Vivus believes FDA is making the new safety request, which came during a Jan. 19 meeting, based on six published reports of children with deformities born to mothers who used topiramate for migraines. In the Qnexa studies, 15 children were born to women exposed to Qnexa or topiramate, none with deformities, the company said. Investors were expecting Vivus to resubmit Qnexa for a second FDA review in early 2011 but the FDA's apparent concern about fetal deformities may delay those plans. On Friday, Vivus said only that the timing of the Qnexa resubmission won't be determined until the company and FDA can reach agreement on the "feasibility" of using existing healthcare databases to find answers about topiramate and oral clefts. Left unanswered by Vivus is what happens if those existing healthcare databases cannot provide the new safety information requested by FDA. FDA rejected Qnexa last October primarily for concerns about the drug's safety but Vivus was hoping to resubmit the weight-loss drug for approval based on new, two-year safety data. Vivus shares were down 13% to $9.10 in Friday pre-market trading. FDA is expected to issue an approval decision on another weight loss drug from Orexigen Therapeutics ( OREX) on Jan. 31. --Written by Adam Feuerstein in Boston. >To contact the writer of this article, click here: Adam Feuerstein. >To follow the writer on Twitter, go to http://twitter.com/adamfeuerstein. >To submit a news tip, send an email to: firstname.lastname@example.org.