Impax Laboratories and DURECT Corp. have entered an agreement granting Impax exclusive worldwide rights to develop and commercialize Eladur, DURECT’s investigational transdermal bupivacaine patch in Phase II development for the treatment of pain associated with post-herpetic neuralgia (PHN).   Impax will control and fund the development program. DURECT will receive $2 million upfront along with potential additional payments of as much as $61 million based on development and commercialization mil...