The US Food and Drug Administration's (FDA) Center for Devices & Radiological Health (CDRH) has released selection of summary review memos of 180-day design changes to medical devices that have already won a green light from the federal watchdog agency.  The memos detail applications to make substantial changes to already-approved medical devices.  The federal watchdog agency's med-tech oversight arm said it began releasing the documents as part of the CDRH's transparency initiative. The 180-day supplements seek to make "a significant change in components, materials, design, specification, software, color additive, and labeling to an approved premarket application or premarket report," according to the agency. (Mass Device)