Bayer MaterialScience LLC has expanded the application of its Baymedix CL 100, a lubricious surface treatment for medical devices, to include the inner lumens of catheter-based devices. Bayer has demonstrated successful modification of the inner lumen surface of microcatheters with inner diameters (IDs) as small as 0.0157 inches. Whether on the inner or outer surfaces of catheters and other devices, the application of Baymedix CL 100 provides a durable coating with a low coefficient of wet friction. Bayer anticipates that the capability to coat narrow inner lumens will be attractive to cardiovascular and neurovascular device designers. In particular, coated lumens may improve the interaction between catheters and guidewires or enable new designs better suited to access distal vasculature. Distinct from other lubricious and hydrophilic coatings, Baymedix CL 100 is directly grown onto the surface of the medical device rather than applied as a separate coating. This unconventional application technology, which uses a physical drying process, is part of why the Baymedix process can be applied to otherwise challenging surfaces like the inner diameters of long microcatheters.