An active ingredient in Vivus’ obesity drug candidate Qnexa has been associated with a higher rate of oral clefts in babies born by mothers who took the drug during pregnancy, reported Vivus.
The top-line preliminary results from Vivus’ retrospective study, named Fortress, showed the utero exposure of topiramate, one of the two active ingredients in its diet pill Qnexa, associated with increased risk of oral clefts in new-born babies. The share price of the Mountain View, CA-based drug developer fall down to 8.7% to $9.50 after the news.
Fortress study examined 1,945 mother-infant dyads, two individuals or units regarded as a pair, who had taken topiramate either alone or in combination with other anti-epileptic agents in the first trimester of pregnancy. Among the 1,740 dyads who were exposed to topiramate alone, five cases of oral clefts in infants whose mother had taken the drug during pregnancy were found, a prevalence rate of 0.29 percent. In comparison, mothers who took topiramate before pregnancy but not during pregnancy has a 0.16% prevalence.
Peter Tam, president of Vivus, commented, “The prevalence ratio for oral clefts in FORTRESS is within the recently reported range for topiramate from several large studies,” he added, “We have shared these results with the FDA. We continue to work closely with the FDA during their review of the NDA and as we prepare for the upcoming Advisory Committee meeting expected in the first quarter of 2012.”
Qnexa is an oral, once-a-day, controlled-release formulation of low-dose phentermine and topiramate. The weight loss drug candidate was developed by Vivus as a treatment for obesity, type 2 diabetes and obstructive sleep apnea. Clinical study data showed that patients taking the drug have had statistically significant weight loss, glycemic, or blood sugar, control, and improvement in cardiovascular risk factors, when used in combination with a diet and lifestyle modification program. Qnexa is currently being evaluated for approval by US and EU regulators for the indication of obesity.
The U.S. agency had raised concerns about the association of topiramate use with birth defects and cardiac effects, rejected the Vivus’ NDA for Qnexa in October, 2010. The company resubmitted its new drug application in October this year with a contraindication for women of childbearing age, and is studying the impact of the drug in pregnant women and babies.
All of the results from the Fortress study are expected in the third quarter of 2012.
Vivus said the FDA’s Endocrinologic and Metabolic Drugs Advisory Committee will review the NDA for Qnexa as a treatment of obesity on February 22, 2012. The U.S. regulators are expected to complete the review by April 17, 2012.