I've searched the internet and Davis's Guide and have come up empty. Under TIME/ACTION PROFILE (Onset, Peak, Duration) for Cefaclor they use a Route abbreviated PO-CD and on Nitroglycerin PO-ER. I assume the PO means by mouth, but can't work out the meanings for CD or ER. On the chance there are more of these odd abbreviations, does anyone know where a table of them are located in Davis's Guide? Thanks Still a student