"In 2007 alone, Wyeth experienced setbacks with Pristiq, Viviant, Aprela and bifeprunox that reduced or erased the commercial prospects of these assets," Schott explains. The FDA rejected bifeprunox for schizophrenia in August 2007.
In July 2007, the FDA granted conditional approval for Pristiq, a non-hormonal treatment for menopausal symptoms. To gain final approval, Wyeth must conduct a clinical trial to assess potential heart and liver side effects. The trial is expected to take 18 months. In February 2008, the FDA approved Pristiq as a treatment for depression in adults.
In May, the FDA granted conditional approval for Viviant to treat postmenopausal osteoporosis. In December 2007, the FDA gave tentative clearance for Viviant to prevent the disease. Final approval for both uses depends on Wyeth's answering the FDA's questions about risks of stroke and blood clots in leg veins, expected by year-end. Schott figures the FDA will act by mid-2009.
Viviant could come to market in 2010, but Schott says Aprela has greater revenue potential. Aprela, which is still in late-stage clinical trials, combines Premarin and Viviant. Clearly, if the FDA rejects or restricts Viviant, potential sales of Aprela will be affected. Wyeth expects to seek FDA approval for Aprela in the middle of next year.