This invention relates to compositions, methods, devices and kits relating to the infusion of a catheter lock solution into an indwelling catheter. Inventive compositions, methods, devices and kits aid in diminishing the effects of microbial infection in catheters and occlusion of the catheters. A lock solution provided by the invention includes citrate and a paraben. The solution preferably has a density suitable for retention of the solution in a catheter during the lock period. Another lock solution provided by the invention includes citrate, a paraben and a photo-oxidant, such as, for example, methylene blue.
