The data from both less-reliable observational studies and clinical trials was conflicting, and Merck began three big cancer prevention studies that could also assess any risk Vioxx caused to the heart.
Then, two months ago, the NIAID signed another agreement to fund clinical trials of VivaGel aimed to study its application for genital herpes prevention.
Peter Kim, Merck's head of research and development, said on the company's conference call that the study for migraine prevention was "exploratory" and used a different dosing schedule than other telcagepant trials.