"Not all Phase IV studies are post-marketing surveillance (PMS) studies but every PMS study is a phase IV study." "Under the current system, the FDA has the au

"Not all Phase IV studies are post-marketing surveillance (PMS) studies but every PMS study is a phase IV study." "Under the current system, the FDA has the authority to revoke approval of some drugs for which Phase IV commitments have not been honored. This authority has never been invoked." http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3148611/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3148611/ http://www.citizen.org/hrg1520 http://www.citizen.org/hrg1520