Abstract: This invention provides a prefilled selectively activatable body-worn infusion-pump assembly for rapid delivery of large volumes or highly viscous volume comprising a housing; a pre-filled aseptically-sealed flexible drug reservoir-containing assembly; a conjoined, coordinately controlled and perpendicularly arranged cannulated needle dispensing and needle insertion assembly operationally connected to and in fluid connection with the pre-filled aseptically-sealed drug reservoir-containing assembly, wherein the cannulated needle dispensing assembly projects generally perpendicularly to a generally planar surface of the housing, promotes insertion of the cannulated needle in skin of a subject and promotes retraction of the needle within the cannulated needle dispensing assembly thereafter, and wherein the needle insertion assembly projects generally in a parallel orientation to a generally planar surface of the housing, which projection initiates opening a fluid path with the pre-filled aseptically-sealed drug