The invention provides methods and compositions for reducing or inhibiting bone resorption, osteoclast differentiation and stimulation and the loosening of medical prostheses by administering a compound or agent that modulates an adenosine receptor such as the adenosine A2A receptor, in particular, an agonist of an adenosine A2A receptor. Such a barrier system can include: a barrier device having a skin-contacting surface and a catheter-receiving surface; and an adhesive composition configured for adhering to skin, the barrier device, andor the catheter so as to form a barrier at or adjacent to an incision in the skin where the catheter is percutaneously inserted through the skin. The contaminants combine with the sacrificial layer and are removed by etching away the sacrificial layer. Motion is augmented by propulsion or repulsion mechanisms, including pressurized liquid stream jet propulsion. This allows the distal tip to be moved across the tissue without dragging or snagging on the tissue.