Method of coating an expandable member, e.g. balloon, is provided, the method comprising providing an expandable member having an outer surface. The method includes a plasma treatment with a supply of gas performed on at least a portion of the outer surface of the expandable member. A therapeutic agent is applied on at least the plasma treated portion of the outer surface of the expandable member after the plasma treatment is performed. The plasma treatment can reduce the adhesion of therapeutic agent to the surface of the expandable member. A medical device made by the disclosed method is also provided.